•                     I   iiiiiHiniiiiMi:GUIDE TO THE STUDY OFJCHENS     SCHNEIDER
^0rtl| Carolina ^late         CQ^oIkgc                                             This book   yjoas   presented        QK...
This book     is   due on the date indicatedbelow and          issubject to an overduefine as posted at the circulation de...
Znx   (Krinnetttuff   an ^eine fHutttv
Ciadonia ciM^toletla
A     GUIDE TO THE STUDY                             OF            LICHENS       ALBERT SCHNEIDER,                 M.   D....
Copyright, 1898By Albert Schneider  All rights reserved
CONTENTS.PrefaceIntroduction                                 PART     I.         The General Consideration of Lichens.    ...
VI                          CONTENTS.                            SECTION       IV.The Morphology and Physiology of Lichens...
CONTENTS.                   VHDescription of Families, Genera and Species   ...    81      I.   Caliciace^                ...
PREFACE.  This    little   work   is   especially written         and arranged for theuse of amateurs in the study of lich...
X                                 PREFACE.opportunity may enter into the consideration of the synonymyand tlie nomenclatur...
PREFACE TO SECOND EDITION.     The changes     to the   second edition are the addition of sixfull-page half-tone illustra...
;                        INTRODUCTION.     Lichens form a group             of plants         which has beennot so      mu...
:Xll                           INTRODUCTION.lends itself so readily to the critical examination of thestudent and to the d...
PART   IGENERAL CONSIDERATION OF LICHENS
THE HISTORY OF LICHENOLOGY.                                   SECTION                I.               THE HISTORY OF LICHE...
2            GUIDE TO THE STUDY OP LICHENS.rius to     De    Notaris (1845)            ;   6,       from De Notaris to1867...
THE HISTORY OF LICHENOLOGT.                                        6In a work ascribed                   to   Solomon a la...
4          GUIDE TO THE STUDY OF LICHENS.CaBsalpiuus          and Camerarius, who were among theearliest   commentators on...
THE HISTORY OF LICHENOLOGY.                              5though some considered them as " mosses " or " fun-goid " mosses...
6           GUIDE TO THE STUDY OP LICHENS.ignated lichens as          ^^                                 rustici pauperrim...
THE HISTORY OF LICHENOLOGY.                                     7first   chemical studies of lichens.                   He...
8          GUIDE TO THE STUDY OF LICHENS.observed the development of the lichen               Collema limOsum from    the ...
THE HISTORY OF LICHENOLOGY.                                              9ology of lichens.                     It must, o...
10         GUIDE TO THE STUDY OF LICHENS.simple lens.     Meyers studies were perhaps even morecomprehensive than those of...
THE HISTORY OF LICHENOLOGY.                                11of   the spermatial characters in                    classifi...
12         GUIDE TO THE STUDY OF LICHENS.This in a nutshell              is   the great discovery of Schwen-dener and whic...
THE HISTORY OF LICHENOLOGY.                                     13   Within comparatively recent years there have been num...
14               GUIDE TO THE STUDY OF LICHENS.conclusion that lichens shotild be considered as a dis-tinct class.        ...
THE HISTORY OF LICHENOLOGY.              15vance has been very slow.   Most of the real scientificprogress has been  made ...
16          GUIDE TO THE STUDY OP LICHENS.                          SECTION           II.                   THE USES OF LI...
THE USES OP LICHENS.                                        17in the        dyeing industry, lichens found a useful placee...
18              GUIDE TO THE STUDY OF LICHENS.the     power    to   burrow      into rock of        any kind, not eveninto...
THE USES OF LICHENS.                              19     All lichens contain a larger or smaller percentageof a starch-lik...
20              GUIDE TO THE STUDY OF LICHENS. tains a high percentage of lichenin.   The peasantry            of Iceland,...
THE USES OF LICHENS.                        21  Theophrastus and Dioscorides described Rocella tincU  oria as a " marine f...
22             GUIDE TO THE STUDY OF LICHENS.volved.        In general,              it   may be    stated that the lichen...
THE USES OF LICHENS.                                23to feed upon.      The wolves eat of tliis and die. Accord-ing to Fa...
24             GUIDE TO THE STUDY OF LICHENS.and readily accessible substitute for quinine.                        Sanders...
WHAT ARE LICHENS                  ?                        25                             SECTION                 III.    ...
26             GUIDE TO THE STUDY OF LICHENS.     If   we   scrape off a small fragment of the green coat-ing of a tree or...
"WHAT ARE LICHENS                   ?                             27of cheese, in tanning, and in                     tlie...
28             GUIDE TO THE STUDY OF LICHENS.convert the independent chlorophyll-bearing organisminto a dependent chloroph...
WHAT ARE LICHENS?                                        29fore, in        mind, that in the discussion of lichens        ...
30             GUIDE TO THE STUDY OF LICHENS.The many          generations of a               life    of     dependent lux...
WHAT ARE LICHENS ?                                                  31If the organisms could in    some way form an associ...
32            GUIDE TO THE STUDY OF LICHENS.assimilation.           The fungus gave                  protection to the alg...
WHAT ARE LICHENS                   ?                         33association of a fungus            and an          alga,   ...
34              GUIDE TO THE STUDY OF LICHENS.descending series with those most nearly resemblingalgae.          From   th...
WHAT ARE LICHENS?                                     35brandling       cliains of rather           oblong irregular      ...
36             GUIDE TO THE STUDY OF LICHENS.     These     brief references to the algae, with the           accom-panyin...
WHAT ARE LICHENS             r*                        37tion.      The method       of reproduction in lichens           ...
B8         GUIDE TO THE STUDY OF LICHEKS.are formed of the elements of both symbionts and cantherefore develop into a     ...
MORPHOLOGY AND PHYSIOLOGY.                                  39                              SECTION              IV.      ...
40             GUIDE TO THE STUDY OF LICHENS.      From what             has already been said of lichens, thereader      ...
MORPHOLOGY AND PHYSIOLOGY.                                           41                            1.   The    Crustose   ...
A guide to the study of lichens
A guide to the study of lichens
A guide to the study of lichens
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A guide to the study of lichens
A guide to the study of lichens
A guide to the study of lichens
A guide to the study of lichens
A guide to the study of lichens
A guide to the study of lichens
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A guide to the study of lichens

  1. 1. • I iiiiiHiniiiiMi:GUIDE TO THE STUDY OFJCHENS SCHNEIDER
  2. 2. ^0rtl| Carolina ^late CQ^oIkgc This book yjoas presented QK5&3 S^4 vv.--^- LIBRARIES NORTH CAROLINA STATE UNIVERSITY S021 78026 Q
  3. 3. This book is due on the date indicatedbelow and issubject to an overduefine as posted at the circulation desk. EXCEPTION: Date due will be earlier if this item is RECALLED. 200M/09-98-981815
  4. 4. Znx (Krinnetttuff an ^eine fHutttv
  5. 5. Ciadonia ciM^toletla
  6. 6. A GUIDE TO THE STUDY OF LICHENS ALBERT SCHNEIDER, M. D., Ph.D. Pharmacognosy, Professor of Botany, Materia Medica and California College of Pharmacy, San Francisco With frontispiece in color and Twenty plates SECOND EDITION BOSTON KNIGHT AND MILLET 1904
  7. 7. Copyright, 1898By Albert Schneider All rights reserved
  8. 8. CONTENTS.PrefaceIntroduction PART I. The General Consideration of Lichens. SECTION I.The History of Lichenology 1 I. From the Earliest Time to Wallroth and Meyer (1825) 2 II. From Wallroth and Meyer (1825) to the Close of 1896 8 SECTION II.The Uses of Lichens 16 I. The Function of Lichens in Nature ... 17 II. The Economic Value of Lichens .... 18 SECTION III.What are Lichens? 25 I. The Origin of a Lichen 29 II. The Relation of the Lichens to Algjs and Fungi 33 in. Lichens as Morphological Units .... 36 •^ 57G1.
  9. 9. VI CONTENTS. SECTION IV.The Morphology and Physiology of Lichens I. The Thallus ... 39 39 1. The Cbdstose Type 41 2. The Foliose Type . -. 42 3. The Fbuticose Type 44 II. The Apothecia 45 1. The Fungal Type 46 2. The Thalline Type 47 III. Accessory Structures 48 1. The Soredia 48 2. The Cyphell-e 49 3. The Cephalodia 50 4. The Spermagonia 50 SECTION V.The Occurrence and Distribution of Lichens ... 52 I. The Latitudinal and Altitudinal Distribution OF Lichens 52 SECTION VI.Lichens and the Naturalist 56 I. The Collection of Lichens 56 II. The Study of Lichens 63 III. The Pbesebyation of Lichens 65 PART II. The Systematic Study of Lichens. SECTION I.Systems of Classification 73 SECTION II.Keys to the Study of Lichens 76 I. Artificial Kky to the More Important Genera OCCUBBINQ IN THE UNITED STATES ... 77 II. Natural Key to the Families 80
  10. 10. CONTENTS. VHDescription of Families, Genera and Species ... 81 I. Caliciace^ SI II, Cladoniace^ 87 III. Lecideace^ 102 IV. Gbaphidace^ . . ; 124 V. Physciace^ 132 VI. Parmeliace^ 144 VII. Verrucariageje 169 VIII. COLLEMACE^ . . 179 IX. Pannariace^ 184Lichens Imperfecti, or False Lichens 201The Continental Range of the Lichens Occurring in THE United States 202Alphabetical List of the Genera and Species Repre- sented in the United States 204General Index 225Plates 235
  11. 11. PREFACE. This little work is especially written and arranged for theuse of amateurs in the study of lichens. By this it is not in-tended to convey the idea that the presentation of the subject-matter is unscientific, incorrect or even out of date. Thetreatment of the subject is in harmony with the most recentresultsobtained by tlie leaders in the study of lichenology I ;have simply endeavored to present these results in such a waythat they may be comprehended by all in other words, an at- ;tempt has been made to popularize our present knowledge oflichens. It should, however, be kept clearly in mind thatonly the known facts or the completed work of science can bepopularized. The advance-work of science, that is, the workwhose aim it is to make 7}ew discoveries or to correct errors, cannever he popularized ; as soon as this is attempted it ceases tobe advance-work. This statement is intended for those of thelaity who are inclined to speak of scientific work as " non-sense " or as " a morbid taste for using big words." It is alsointended for the serious consideration of those would-be scien-tists who are too anxious to "popularize science." It isfurther hoped that this statement will avoid possible erro-neous conclusions as to the intended purpose of this book. The existing nomenclature-difiiculty does not concern orinterest the average student of nature. In fact, the leading themselves as yet wholly at sea as toscientific specialists arewhen and where the controversy will end. For this reasonthe citation of authorities is omitted. Tlie names given arewell authenticated, so that those who have the desire and the
  12. 12. X PREFACE.opportunity may enter into the consideration of the synonymyand tlie nomenclature-controversy. The lichens described are. the more common forms occur-ring in the United States, those with which tlie collector islikely to come in contact. At the close is given a fairlycomplete list of the lichens found in the United States this ;will prove helpful to those who wish to make exchanges.The artificial key is especially intended for the use of thosewho are not in possession of a compound microscope. I take this opportunity to express my grateful obligationsto Dr. N. L. Britton and Prof. Lucian M. Underwood, ofColumbia University, who placed at my disposal the Univer-sity collection of lichens. I am also greatly indebted to mywife, who has kindly given aid in correcting the manuscriptand in reading the proof. Albert Schneider. Chicago, January, 1898.
  13. 13. PREFACE TO SECOND EDITION. The changes to the second edition are the addition of sixfull-page half-tone illustrations of typical representatives ofthe three gieat subdivisions of the lichens ; namely, thecrustose, foliose, and fruticose. These veill be of greatvalue to beginners in the study of this remaikable group ofplants. Since the issue of the first edition no important discov-eries have been made in lichenology, hence no changes havebecome necessary in the text. I take this opportunity to express my obligations to MissAlice Eastwood, of the California Academy of Science, andK. S. Gray, Attorney, San Francisco, for the loan of mate-rial, as well as for assistance in collecting specimens. Albert Schneider. San rRANCisco, August, 1903.
  14. 14. ; INTRODUCTION. Lichens form a group of plants which has beennot so much overlooked and neglected as misunder-stood and abused. The term lichen is rather un-familiar, but not so the term " moss," by which theplants here referred to are quite generally knownto layman as well as to poet. And, indeed, the termmoss is justifiable if we trace it to its Scandinavianorigin. All comparatively small thalloid cryptogams— that is, flattened, stemless and flowerless plants —were known as moss (most, mossa, moos, mus). Theterm, therefore, included lichens, liverworts and mossesproper. But from the present standpoint of sciencelichens are not mosses, as will be made clear laterlichens are an independent group of plants having nogenetic relationship to mosses. Nor must it be supposed for a moment that lichensare uninteresting and insignificant. With the one ex-ception of marine algae, no plants present such trulybeautiful and artistic features to the amateur in nature-study. No group of plants is so easily obtainable or
  15. 15. :Xll INTRODUCTION.lends itself so readily to the critical examination of thestudent and to the decorative fancies of the artisan.Neither is it necessary to enter a plea for the kindlyconsideration of these plants because they have beenneglected and abused. Lichens do not require pitythey are more than competent to hold their own inthe great struggle for existence. Indeed, many of themuch petted and much praised higher plants owe theirvery existence to the lichens. It is true, lichens can-not boast of an exalted origin or noble ancestry, butthey have gradually advanced in a beneficent life-work,so that at present their lowly origin is wholly lostsight of. Let us, therefore, obtain a better insight into theseplants, so that we may judge them more fairly and as-sign them to their proper position in the world of life,and duly credit them with the grand work they areperforming. Let us hope that no one, on seeing alichen, will say, " Oh ! that is a moss," or, " Its noth-ing ; it just grows on trees." A lichen is as deservingof recognition as the oak upon which it grows or thereindeer whose life it sustains.
  16. 16. PART IGENERAL CONSIDERATION OF LICHENS
  17. 17. THE HISTORY OF LICHENOLOGY. SECTION I. THE HISTORY OF LICHENOLOGY. The history of lichenology is a remarkable one. Itindicates that this special science has progressed in adevious and interrupted course. It is only within afew years that scientists have arrived at any compara-tive certainty as to the true nature of these plants.Wonderfully absurd opinions were entertained as totheir origin and economic uses. For these reasons abrief historical review is not only interesting buthighly important. Historically, time is usually divided into periods orepochs ; such divisions are, however, more or lessarbitrary and depend somewhat upon the judgment ofthe author. The establishment of periods very greatlysimplifies the presentation of an historical review. Itmust, however, not be supposed that the greater thenumber of epochs or periods the simpler the history;generally the contrary is true. The most exhaustive history of lichenology is thatby Krempelhuber, published in the year 1867. Thisauthor divides the history of our science ii^to sixperiods, as follows : 1, from the earliest times (Theo-phrastus) to Tournefort (1694) ; 2, from Tournefortto Micheli (1729) ; 3, from Micheli to Weber (1779) ;4, from Weber to Acharius (1810) ; 5, from Acha- Library N. C, State Collect
  18. 18. 2 GUIDE TO THE STUDY OP LICHENS.rius to De Notaris (1845) ; 6, from De Notaris to1867. In my * Text-book of General Lichenology"I have retained Krempelhubers limitations of thefirst three periods ; the others have been changed,and the review has been completed to the beginningof 1897. As thus modified, the fourth period is fromWeber Wallroth and Meyer (1825), the fifth from toWallroth and Meyer to Schwendener (1868), thesixth from Schwendener to Reinke (1894), and theseventh beginning with Reinke. The reasons forthe changes will become evident upon the considera-tion of the historical review as here given. For the purposes of a very brief review it wasthought best to recognize two grand periods. Only afew of the more important workers in lichen ology willbe mentioned. At the present time the publications onlichens number many thousands to collect and digest ;these is the work of years. The beginner will, how-ever, feel somewhat relieved to learn that of thethousands of publications on lichens only a compara-tively few are of any intrinsic value or add to ourknowledge of the subject.I. FROM THE EARLIEST TIME TO WALLROTH AND MEYER (1825). This may be characterized as the period in whichno real scientific study was made of lichens. Thebotanical systematists of the time devoted their at-tention to the higher plants, especially those of realor imaginary economic value. The lower plantswere quite generally neglected, lichens in particular.
  19. 19. THE HISTORY OF LICHENOLOGT. 6In a work ascribed to Solomon a large number ofhigher plants are mentioned but not a single crypto-gam. The reason why lichens should be especiallyneglected becomes apparent when we consider thatwith few exceptions they are not striking in size,color or form, nor do they seem to possess any markeduseful or harmful properties. No historian has been able to give any reliable in-formation regarding the earliest knowledge and usesof lichens. Evernia furfuracea is said to have beenfound with Egyptian mummies, where it was doubtlessused as packing material. There is no reason whythis lichen as well as others (species of JJsnea in par-ticular) should not have been used for similar pur-poses by the ancient peoples of northern Africa, Arabia,Italy and other countries in which these plants occurvery plentifully. Theophrastus (371-286 B. C), apupil of Aristotle, was perhaps the first writer wholeft any record of lichens. From his rather imperfectdescriptions we are led to believe that he was moreor less familiar with JJsnea barhata and Rocella tincUoria. The former no doubt attracted attention be-cause of its beard-like growth upon trees, oaks in par-ticular. The latter has been long known on accountof its coloring properties. These two lichens werealso mentioned in the works of Dioscorides andPliniiis. With these exceptions, lichens received noattention until the sixteenth century, when science,art and literature awoke from the paralytic state intowhich it had sunk since the first century. About themiddle of the sixteenth century, Ruellius, Gessner,
  20. 20. 4 GUIDE TO THE STUDY OF LICHENS.CaBsalpiuus and Camerarius, who were among theearliest commentators on the writings of Theophrastus,Dioscorides and Plinius, did little more than to reiter-ate what was already known of lichens. At the closeof this century about twenty-eight species or forms oflichens were described. The Scotch botanist Morison(1683) described fifty-six lichens, some of which werequite well figured. The Italian botanists were the beginners in thestudy of the structure and growth of lichens. Mal-phigi (1686) was the first to call attention to thesoredia, which he considered to be the true seeds oflichens, since he had observed that new plants weredeveloped from them. Porta (1591) gave some verycrude explanations of the origin and growth of lichens,which indicated that he had some fairly correct ideasof the nature of these plants, while Morison, whoseemed to have been an accurate observer otherwise,expressed it as his opinion that lichens were excremen-titious matter produced by the soil, rocks and trees. At the close of the seventeenth century about 125lichens were known and described. Especially im-portant was the work of Tournefort (1694-1719).This author called special attention to the apotheciaand some of the spores. His descriptions of the his-tological characters were of necessity crude, owing tothe imperfections of the simple microscopes, the com-pound microscope being as yet unknown. The systematic study of lichens really began withthe Florentine botanist Micheli (1729). Heretoforeall lichens had been placed in the one group " lichen,"
  21. 21. THE HISTORY OF LICHENOLOGY. 5though some considered them as " mosses " or " fun-goid " mosses. Micheli proceeded to arrange all theknown species or forms into thirty-eight orders basedupon the general macroscopical characters and the con-sistency of the thallus. He illustrated the orders andalso studied the apothecia and the spores. Twelve yearslater John Dillen issued his noteworthy " Historia Mus-corum," in which the lichens are classified as mosses.His work is well illustrated, and in many respects thesystem of classification is superior to that of Micheli. After the above botanists others exercised theiringenuity in establishing systems of lichens. Someauthors classified them with mosses, while othersplaced them with fungi. The various groups werequite universally based upon the external appearanceand nature of the thallus. Linne, " the immortalSwede" (1753), combined all lichens in one group inagreement with Tournefort. He, however, establishedsub-groups based upon the characters of the thallusas well asupon those of the apothecia. It will be remembered that at first there was a ten-dency to classify lichens as a distinct group of plants ;later to consider them as mosses or even as funafi. oThis doubt and uncertainty continued to grow untilthe close of the seventeenth century, when the confu-sion reached its highest point. They were not onlyclassed as mosses and fungi, but also as algae, sponges,liverworts, etc. This difference of opinions was dueto the fact that the knowledge of the lower plants, oflichens in particular, was very imperfect. Linne, whonever pretended to be a friend of the cryptogams, des-
  22. 22. 6 GUIDE TO THE STUDY OP LICHENS.ignated lichens as ^^ rustici pauperrimi, which mightwell be translated as " the poor trash " of vegetation.This lack of interest in the lower organisms was quiteuniversal and explains why lichens were neglected,particularly the really insignificant crustose forms.As the result of the combined efforts of the variouslichenographers some 500 species or forms of lichenswere known at the close of the eighteenth century. The first investigator who made an attempt to studythe morphology and physiology of lichens was J.Hedwig (1784). Though his conclusions were in themain wrong, yet his investigations served as a stimulusand an inducement to further study. This author,was the first to make a special study of the sperma-gonia. He also studied the spores and soredia.He believed that the spermagonia were the first todevelop and that the apothecia and soredia developedupon these subsequently. Furthermore, the sper-magonia were looked upon as the male reproductiveorgans, the soredia as the fertilizing elements andthe apothecia with the spores as the female organs.A. P. De Candolle made some interest- (1798)ing experiments as to manner in which the thedifferent lichens take up their food-supply. Duringthe same year Acharius, who is often spoken ofas the " father of lichenology," issued his " Prod.Lich. Suec," in which he expressed great uncertaintyin regard to the manner of fertilization and the natureof the reproductive organs. He even questionedwhether lichens were plants and expressed a desire toclassify them as polyps. Georgi (1779) made the
  23. 23. THE HISTORY OF LICHENOLOGY. 7first chemical studies of lichens. He found that theycontain such organic substances as oil, resin andmucus and various inorganic salts. In the year 1810Acharius issued his " Lichenographia Universalis,"which was the most voluminous and complete workon lichens yet issued. It is simply a manual of lichenswith rather imperfect descriptions of species. Hisillustrations, particularly those of the spores, are poor.One would expect betterwork from so eminent a bot-anist. He did not make use of the spore-charactersin his system. Other eminent botanists, as Lamarck,De Candolle, Fries, F^e and Eschweiler, establishedsystems of classification ; all of which were artificialand inadequate. Some of the leading botanists of the time believedthat lichens were related to fungi as well as to thealgae. Accordingly Agardh, Voigt, Endlicher, Lind-ley, Reichenbach and others considered lichens as adistinct class to be placed between the algae and fungi.Sprengel and Oken also considered them as a distinctclass but placed them between liverworts and algaeDe Candolle placed them between liverworts andfungi. Many other botanists still considered lichensas a subordinate group belonging to various naturalclasses, as algaj, fungi, mosses, etc. At the beginning of the nineteenth century thebelief in spontaneous generation was quite general.Sprengel and others were convinced that, under favor-able circumstances, lichens were evolved from decayingsubstances, or the decomposition of water. Agardh(1820), the eminent algologist, stated that he had
  24. 24. 8 GUIDE TO THE STUDY OF LICHENS.observed the development of the lichen Collema limOsum from the alga Nostoc muscorum var. lichenoides.A general belief of that time was that the so-called" primal substance," or " green substance of Priestley "(perhaps Protococcus vulgaris or other unicellularalga) could develop into algae, lichens, mosses andother lower plants. Nees von Esenback was wont toguide his pupils to the old castle at Pottenstein inorder to demonstrate ad oculos how the green sub-stance of Priestley occurring on the stone walls coulddevelop into a lichen, while if placed in water it woulddevelop into an alga. Thus we see that during this entire period, whichextended over two thousand years, scarcely anythingmore was done than to name and roughly describebetween 500 and 600 species of lichens. The heateddiscussion, the wrangling and the uncertainty in regardto the origin and position of lichens was simply evi-dence of ignorance and not a sign of profound knowl-edge of the subject. Scarcely a ray of scientific lighthad as yet penetrated the Stygean darkness in whichthese highly interesting plants were enwrapped. Itsimply shows that scientific progress, like all progress,is slow and its devious path is strewn with thorns ands tu mblin g-blocks II. FROM WALLROTH AND MEYER (1825) TO THE CLOSE OF 1896. This might be designated as the period of scientificlichenology. Leading botanists now began to studythe life-history, the morphology, histology and physi-
  25. 25. THE HISTORY OF LICHENOLOGY. 9ology of lichens. It must, of course, be cmpliasizedthat this was heretofore practically impossible owingto the imperfections of the microscope. The com-pound microscope was introduced at the beginning ofthe nineteenth century, but, like all innovations, wascomparatively imperfect and was looked upon withdisfavor by many scientists who should have knownbetter some even going so far as to openly assert ;that the compound microscoj)e would never excel themost perfect simple lenses. The impetus to the scientific study of lichens wasgiven by two German scientists, Wallroth and Meyer,who, peculiarly enough, began their work independentlybut covered much the same ground and published theirresults in the same year (1825). Both made a specialstudy of the morphology, growth and metamorphosisof the lichen-thallus. Wallroths style is very in-volved. Each sentence contains a long series ofparenthetical clauses often occupying nearly an octavopage. His terminology is also peculiar and requires aspecial study. On one question the two eminentwriters were diametrically opposed ; while Meyerbelieved in the spontaneous generation of lichens,Wallroth did not, it being his opinion that they de-veloped from gonidia and spores as well as by vegeta-tive propagation. Wallroth gave a very detailed de-scription of the structure and function of the gonidia,soredia and apothecia as well as of the tliallus. Al-though this author did most excellent work there is noevidence to show that he made use of the compoundmicroscope ; in some instances he did not even use the
  26. 26. 10 GUIDE TO THE STUDY OF LICHENS.simple lens. Meyers studies were perhaps even morecomprehensive than those of Wallroth. He enteredinto a careful investigation of the structure and meta-morphosis of the thallus and apothecia, the gonidiaand spores, the growth and nutrition of lichens andtheir relation to the substratum. Stitzenberger (1862) was perhaps the first to em-phasize the importance of the spore-characters in theclassification of lichens. According to this author itis principally the generic distinctions which are to bebased upon the spore-characters. Lichens withcolored and colorless spores are not to be included inthe same genus, nor those whose spores differ in thenumber or direction of the septa, etc. According tothe systematist Kbrber (1865) 1,051 species of lichenshad been collected in Germany and Switzerland. Ofthis number Korber described 272 species as new.Massalonga (1853) made a careful study of the struct-ure of crustose lichens and concluded that the spore-characters as well as the form and structure of theapothecia and thallus should be considered in the es-tablishment of genera. Fries (1861) recognized theimportance of the spore-characters but considered theform of the spermatia as of nearly equal significance ;in this he was seconded by other authors. The Eng-lish lichenologist Mudd (1861) rightly objected to thisprocedure because nothing was known of the functionof spermagonia and also because the spermatia werenot sufficiently varied in form to be of marked impor-tance in classification. Nylander (1858) more thanany other investigator has emphasized the importance
  27. 27. THE HISTORY OF LICHENOLOGY. 11of the spermatial characters in classification. Thisauthor, however, did excellent work in the morphol-ogy of lichens. He was also the first to point out thedouble affinity of lichens ; on the one hand theyshowed a close resemblance to fungi, on the other toalgae. He published a list of all the known lichens,which included 1,348 species, 298 of which were de-scribed as new. Nasgeli (1847) classified lichens asalgae under the group Lichenaceae and placed them be-tween the Confervaceae and Exococcaceae. Itzigsohns(1854) opinions underwent great change as regardsthe spermagonia. At first he was inclined to lookupon them as parasitic fungi, abnormal spore-organs,apothecia or even parasitic lichens. Subsequently hestated that they were the antheridia analogous tothose of mosses, of which the spermatia were thespermatozoa. Somewhat later he was inclined to be-lieve that the gonidia were the female organs and thespermatia the male organs. Species of the algaePleurococcus^ and others, were supposed to Ulothrix,be free unfertilized gonidia. Tulasne (1852) gave usa very complete and scientific memoir on the histol-ogy of lichens. Lindsay (1856) wrote a most excel-lent popular on British lichens. treatise A littlelater Schwendener (1858-1868) began his morpho-logical studies of lichens which were even more com-plete than those of Tulasne. In 1868 Schwendenercame to the conclusion that the so-called gonidia oflichens were nothing more nor less than simple-celled and that the spore-bearing portion of the lichenalgaewas a fungus living parasitically upon the algae.
  28. 28. 12 GUIDE TO THE STUDY OF LICHENS.This in a nutshell is the great discovery of Schwen-dener and which has revolutionized the study oflichens. Reinke (1873) pointed out that the relationof fungus and alga as it occurs in the lichen was notordinary parasitism ; that it indicated a relationship inwhich both organisms were benefited. This relation-ship he designated consortism. De Bary (1879) de-scribed this phenomenon more fully and designated itsymbiosis, that is a "living together" for mutualbenefit. As a result of Schwendeners investigations lichenswere considered as fungi and were classified as such.There was, however, great opposition to this methodof classification, especially on the part of the puresystematists. In 1874 Stahl made a special study ofthe spermagonia which led him to conclude that thespermatia were the male fertilizing elements. Sturgis(1890), an American scientist, seconded the conclu-sions of Stahl. To Tuckerman we owe most of oursystematic knowledge of the American lichens. Hisdescriptions of species, carefully given, makes hiswork the first that could be utilized by those of ordi-nary capabilities. The style of Leightons manual ofBritish lichens is peculiar ; the descriptions of speciesare given in a peculiar mixture of English and Latinwhich made it necessary for him to append an exten-sive glossary of terms. Crombie (1895), also a Brit-ish lichenologist, retains the same style. Hue (1892)has published a list of lichens from which it may beconcluded that about four thousand species are knownat the present time.
  29. 29. THE HISTORY OF LICHENOLOGY. 13 Within comparatively recent years there have been numerous investigators who have made a special study of the relationship of fungus and alga as they occur in a lichen. We cannot cite authors nor enter into anydiscussion of the results obtained. The general conclusions may be summarized as fol-lows : 1. Certain algae, mostly of the simpler Chlorophy-ceae and Cyanophyceae have entered into an intimatebiological relationship with certain fungi mostly de-rived from the Ascomycetes (sac-fungi). 2. A lichen is represented by a fungal portion andan algal portion. The two parts enter into a sym-biotic relationship which is of such a nature that bothare very materially benefited. The two organismsare complementary to each other, one supplies whatthe other lacks. 3. The fungal portion cannot exist independently,while the algal portion can. 4. The algal types are fairly well known. Theyare (1) Cystococcus humicola which occurs in themajority of lichens ; (2) Pleurococcus vulgaris ; (3)Exococcus ; (4) Glceocapsa ; (5) Chroococcus ; (6)Nostoc ; (7) Stigonema; (8) Chroolepus ; (9) Con-fervacece. Bornet, Baranetzky, Famintzin and Woronin areamong those whose efforts have aided in giving us amore exact knowledge of lichens. Jumelle (1892) isperhaps the first who has entered into a careful studyof the carbon-assimilating function of lichens. Reinke(1894-1896) after considerable study came to the
  30. 30. 14 GUIDE TO THE STUDY OF LICHENS.conclusion that lichens shotild be considered as a dis-tinct class. According to this author a lichen is asmuch a morphological unit as a fern or an oak. Alichen is not a fungus parasitic upon algae. He hasshown that the existence of the lichen is dependentupon the relationship of the fungal portion and thealgal portion.Separating the two destroys the lichen.Lindau (1895) objects to Reinkes views and agreeswith Schwendener. Darbishire (1897) is a strongsupporter of Reinke. He has also made a carefulstudy of the soredia (soralia) as they occur in thePertusarias. As for myself I favor Reinkes view aswill be explained more fully later. Thus concluding the historical review with the be-ginning of the year 1897, we find the status of ourknowledge of lichens somewhat as follows 1. Schwendeners theory of the dual nature oflichens is quite universally accepted as correct. Thatis, a lichen consists of a fungal and an algal por-tion. 2. Reinkes theory of the autonomy of lichens isbeginning to receive general recognition. Accordingto this view a lichen is not a fungus parasitic uponalgae. The mutual interdependence of the fungus andalga is so great that in many instances neither canexist alone. 3. Lichens doubtless form a distinct class equal insystematic importance to mosses, fungi, liverworts,etc. From this historical review we learn that lichenol-ogy has had a very checkered career and that the ad-
  31. 31. THE HISTORY OF LICHENOLOGY. 15vance has been very slow. Most of the real scientificprogress has been made within the past thirty or fortyyears. Considerable work is yet to be done beforeour knowledge of lichens arrives at any considerabledegree of accuracy.
  32. 32. 16 GUIDE TO THE STUDY OP LICHENS. SECTION II. THE USES OF LICHENS. Whatever exists, exists for a purpose. If it existsfor a purpose, it serves some use in the economy ofnature. In many instances this purpose or use is notapparent because not understood. If a thing is decriedas useless it simply indicates that it is not sufficientlyunderstood. Nature produces no useless things. Fromthe standpoint of the optimist, all things, inclusive ofthose designated as bad or harmful, work ultimategood. As indicated in the historical review, lichens havebeen unfairly judged. They have been looked uponas vegetable monstrosities. One comparatively recentauthor considered them as mosses which had beenchecked in their development. Linne looked uponthem as the " beggarly among plants." Others con-sidered them as waste products of earth, rocks andtrees. They were quite generally considered as alto-gether insignificant and useless, if not harmful. Evenpoets were inclined to speak of them disparagingly.The great part that lichens play in the economy ofnature was wholly overlooked. There were, however,a few who ascribed to these plants medicinal propertieswhich they do not possess. As an article of diet and
  33. 33. THE USES OP LICHENS. 17in the dyeing industry, lichens found a useful placeearly in the history of civilization. I. THE P^UNCTION OF LICHENS IN NATURE. The task that lichens perform in the economy ofnature is indeed Herculean and out of all proportionto their size. They are the hardy pioneers preparingthe way for the advance of the less hardy vegetation.Their hardiness is shown by their ability to resistgreater extremes of temperature than any other plants,or even animals. They have gained the reputation ofbeing able to live on nothing but air and sunlight.This is, perhaps, scarcely true, but it is a fact that theyrequire less organic food than other plants. In gen-eral, lichens are to be compared to green chlorophyll-bearing plants, since they take up carbon dioxide fromthe air and give off oxygen. They thus add their mitetoward keeping the air in a suitable condition for therespiration of higher animals. The most important function that lichens performin nature is the preparation of soil. Many of thecrustose lichens occur upon the hardest rock, to whichthey are closely attached, forming dirty grayish orgreenish patches. Erroneous opinions as to the man-ner in which lichens disintegrate the rock are veryprevalent. A recent author puts it as follows : " Onepeculiarity of some power they have to lichens is theburrow into the hardest rocks, even flint and granite,thus making for themselves homes (faveoli)." Otherauthors make similar statements. Such statementsare wholly unscientific, hence untrue. No lichen, has
  34. 34. 18 GUIDE TO THE STUDY OF LICHENS.the power to burrow into rock of any kind, not eveninto vegetable tissue ; such a thing is physically im-possible. Nevertheless lichens disintegrate the hardestrock, and it is done approximately in the followingmanner : Rock-lichens, as well as others, secrete vari-ous acids which have a solvent action upon the lessresisting rock-particles. As a result the rock crumblesand the hyphse of the lichen extend between the loos-ened particles. The lichen may thus be almost entirelyimbedded in the disintegrated rock-material ; the wholemass being held together and to the unaffected rockthe gelatinous hyphse. In time the lichen dies, decaysand becomes mingled with the rock-particles, forminga suitable substratum for the higher lichens, such asthe large foliose and fruticose forms. In turn thesealso decay and aid in forming a suitable soil for mosses,ferns and even higher plants that is, death and decay ;gives rise to new life. Throughout nature we findthat those living give up their lives that others maylive. Lichens are the most altruistic of all living or-ganisms, since they live wholly for the good of others.Nearly all other plants require at least a substratumresulting from the death and decay of others. Manylichens live upon wholly inorganic substrata and exerttheir entire life-energy for the benefit of other livingcreatures. II. THE ECONOMIC VALUE OF LICHENS. We shall here refer to some of the more importantuses to which lichens have been put. Other specialuses will be referred to in the discussion of the species.
  35. 35. THE USES OF LICHENS. 19 All lichens contain a larger or smaller percentageof a starch-like substance known as lichenin, or lichen-starch. It has the same chemical composition asstarch (Cg H^o O5) but differs in that it usually doesnot give the blue reaction with iodine. It is to thissubstance that lichens owe their nutritive properties.From time immemorial the poor of various countrieshave made use of lichens as an article of diet, justwhen it was first so used is impossible to determine ac-curately. Excavations of prehistoric cave-dwellings^ermany) have revealed the presence of lichens(Cladonia rangiferind) among the bones of variousanimals, which would indicate that man of that earlyperiod had already made some economic use of lichens.The " miraculously " supplied manna of the Israelites(Exodus xvi, 14, 15) in the wilderness is supposed tohave been a species of Lecanora (Z. esculentd). Thislichen occurs very plentifully in the mountainous dis-tricts of Tartary, Algeria and other parts of northernAfrica. The plant occurs in small nodular masses,grows and spreads quite rapidly under favorable con-ditions. These lichens are only loosely attached tothe substratum, so that they are readily torn loose andcarried by the wind into the valleys below, where theignorant and oftentimes hungry peasants suppose themto be bread rained from heaven. Travellers in the abovecountries have reported several noteworthy and exten-sive "rains of manna." The Kirghiz Tartars eat thislichen under the name of -earth-bread." Iceland moss {Cetraria islandicn) h;is been mostextensively used as an article of diet because it con-
  36. 36. 20 GUIDE TO THE STUDY OF LICHENS. tains a high percentage of lichenin. The peasantry of Iceland, Norway and Sweden powder it and mix it with the flour of various cereals and mashed potatoes, from which an " uncommonly palatable and healthful bread is prepared." A diet of this lichen was also said to prevent a peculiar form of scurvy, or elephan- tiasis, known as " Iceland scurvy," quite prevalent in Iceland and the Scandinavian peninsula. Rock-tripe, a species of Umbilicaria, has often been the means of saving the lives of arctic explorers, not-ably the members of the Franklin expedition, also oftrappers and hunters in Canada and Alaska. Someof the companions of Franklin found, to their sorrow,that a diet of this lichen produced a severe intestinalinflammation, no doubt due to the bitter principle itcontains. more or less present This bitter principle isin all lichens, and is said to be removed by repeatedwashings or soaking in a solution of potash or someother alkali. In the northern countries of Europe acommon method of preparing lichens for the table wasto make a decoction in milk after they had been re-peatedly washed in water. It is, however, very difl[i-cult to remove the objectionable bitter principle entirely,and for this reason lichens were never extensively usedas an article of diet, excepting in cases of famine. Thepeasants of Norway and Sweden collect large quantitiesof various lichens as fodder for their cattle. Everyone is familiar with reindeer-moss (^Gladonia rangi-ferind) as a food-supply for the reindeer of Lapland. Perhaps the most important and oldest use to whichlichens had been put was in the dyeing industry.
  37. 37. THE USES OF LICHENS. 21 Theophrastus and Dioscorides described Rocella tincU oria as a " marine fungus growing upon rock, possess- ing coloring properties," from which it is concluded that dye made from the lichen was known before that time. It was in use before the time of Pliny. The "blue and purple" of the Old Testament (Ezekiel, xxvii, 7) no doubt refers to the coloring substance obtained from this lichen. After the fall of the Roman empire the knowledge of the use of the dye obtained from Rocella seems to have been lost. About the year 1300, Federigo, a Florentine of German parentage, accidentally redis- covered the method of preparing and using this dye. He is said to have achieved such great success in hiscommercial transactions therewith that in time he be-came the head of a distinguished family, the Oricellarii,who were later known as the Rucellarii and Rucellai.From these names are derived orseille, the namegiven to the coloring substance, and Rocella, the groupof lichens from which orseille was prepared. Formore than a century Italy supplied the market withorseille derived mainly from lichens collected on theislands of the Mediterranean. After the discovery ofthe Canary Islands, in 1402, much of the dye was ob-tained from those islands; still later from the CapeVerde Islands, as well as from other islands and coun-tries. Later it was found that species of Lecanora,Pertusana, Umbilicaria, Gyrophora, etc., yielded ex-cellent dyes. The method of preparing the dye is quite compli-cated andmany complex chemical reactions are in-
  38. 38. 22 GUIDE TO THE STUDY OF LICHENS.volved. In general, it may be stated that the lichen ispulverized and macerated for some time in some alka-line solution, as lye, or ammonia, whereby a beautifulpurple color is obtained. Orchill, cudbear and lit-mus are different names for thesame coloring sub-stance. The first is the English preparation whichoccurs as a rich purple paste ; the second is the Scotchpreparation which is found in the market as a carmineor crimson powder the third is the Dutch prepara- ;tion and occurs in small oblong cakes of an indigo-blue color. Litmus, as well as the other dyes,has the peculiarity of turning red in the presence ofan acid and blue in the presence of an alkali. Thelitmus-paper so extensively used in chemical labora-tories is ordinary filter paper dipped into a neutralsolution of litmus. Later orseille was used principally in dyeing silkengoods. France more than any other country improvedupon the methods of extracting the dye, as well as inapplying it. As to the value of the dye it may bestated that about the middle of this century the" orchella-weed " sold at prices ranging from $100 tomore than $1,000 per ton. The chief objection to theuse of orseille is its instability, being subject to fadingfurthermore, the process of dyeing is very apt to injurethe cloth. Orseille is also used by artists as a pigment. In Sweden Evernia vulpina is known as " Ulf-mossa" (Wolfs moss), because it was said to havebeen used in poisoning wolves. According to Virey,the lichen is powdered and mixed with powderedglass, which is sprinkled upon meat exposed for wolves
  39. 39. THE USES OF LICHENS. 23to feed upon. The wolves eat of tliis and die. Accord-ing to Fabricius, nux vomica^ and not powdered glass,"was mixed with (he lichen, which seems more probable.Tlie dog-lichen {Peltigera canina) formed the basisof the noted " anti-hydrophobia powder " (pulvis anti-lyssns or pulvis contra rabiem) of the London Phar-macopoea (1721 to 1788). In the history of theRoyal Society (London) it is recorded that severalmad dogs belonging Duke of York were cured to theby this powder. Dr. Mead recommends the followingtreatment in a case of hydrophobia " The patient is :bled and ordered to take a dose of the powder (equalparts of the lichen and red pepper powdered) in warmmilk for four consecutive mornings ; thereafter hemust take a cold bath every morning for a month andfor two weeks subsequently three times a week."Dioscorides recommended Usnea harhata, known asthe " beard moss," in certain diseases peculiar towomen. Later was very highly prized as a remedy itfor whooping-cough, epilepsy and as an anodyne. It alsoformed the main ingredient in powders recommendedto promote the growth of hair. The yellow Physciaparietina was considered a specific in jaundice andwas also used as a substitute for quinine. During theNapoleonic wars (1809-1815) fevers of all kindsraged in the military hospitals. Quinine, which wasthen the popular remedy for fever, became very scarce,on account of its rapid consumption and because of thecommercial blockade which prevented its importation.Tlie Austrian government therefore offered a prizeof five hundred ducats for the discovery of a cheap
  40. 40. 24 GUIDE TO THE STUDY OF LICHENS.and readily accessible substitute for quinine. Sanders,who secured the prize in part, proposed Physciaparietina as such a substitute. It proved, however,very unsatisfactory and its use was soon entirely dis-continued by physicians. From their alleged aptitude for imbibing andretaining odors and scents the powder of several fruti-cose lichens formed the basis of certain perfumeswhich were celebrated in the seventeenth century.The astringency some species rendered them ser- ofviceable in tanning and even in brewing the beer of ;a certain Siberian monastery, celebrated for its peculiarbitterness, owed this to French Sticta pulmonaria.and Scandinavian chemists employed Cetraria island-tea and Cladonia rangiferina in the manufacture ofalcohol. The method of procedure is essentially asfollows: The lichens are treated with sulphuric orhydrochloric acid, which transforms the lichenin intoglucose ; this, being allowed to ferment, producesalcohol. Two pounds of the lichen furnishes aboutone pint of alcohol. Attempts were also made to use lichens in themanufacture of paper but the results were very unsat-isfactory, as these plants contain no tenacious fibres.They are still very extensively used in the decorativework of the taxidermist. Some species furnish a gumused in the manufacture of pasteboard. In conclusion, it may be stated that the medicinalvirtues of lichens are largely imaginary. The only offi-cinal lichen to-day is Cetraria islandica, a decoction ofwhich is recommended as a tonic for convalescents.
  41. 41. WHAT ARE LICHENS ? 25 SECTION III. WHAT ARE LICHENS? In order to comprehend the true nature of lichensit is necessary to have a correct idea of their originwe must have some conception of their j^osition innature, of their relation to other plants. Lichens ori-ginated in a manner wholly different from any othergroup of plants. Their history of development is mostremarkable, and stands without a parallel in the worldof living things. In order to make clear this wonder-ful origin and development it is necessary to enter intoa brief consideration of fungi and the lower algae. Theimpatient reader may ask, "What do fungi and algashave to do with lichens ? " He will soon learn thatwithout these plants lichens could not have come intoexistence. We shall begin the discussion with algae. Every one is more or less familiar with the loweralga2 ; they occur plentifully upon tree-trunks, fences,upon flower-pots, walls and woodwork of greenhouses,etc.; they form the green scum on ponds and brooks, inwatering-troughs, in fact, in nearly all moist })lacesand in water exposed to sunlight and warmth. Theseplants are very small, the individual plant is, in fact,too small to be seen by the naked eye. Several hun-dred must become associated to form a minute greenspeck.
  42. 42. 26 GUIDE TO THE STUDY OF LICHENS. If we scrape off a small fragment of the green coat-ing of a tree or flower-pot and examine it under amicroscope we find that it consists of numerous minuteglobules, perhaps five-thousandths of an inch in diam-eter. Each globule is an individual alga and is nothingmore or less than a single cell. Not all of the loweralgae are single-celled however ; many consist of chainsor filaments of cells or even of a highly complex struct-ure. The algae with which we are concerned are eithersingle-celled or form simple or branching chains ofcells. Their structure will be more fully describedlater. Algae contain a green substance known as chloro-phyll. It is this substance which enables the organismto assimilate inorganic food ; a function peculiar to allchlorophyll-bearing plants and which distinguishes themfrom animals and parasitic plants. Animals and fungican only assimilate the food-substances directly or in-directly prepared by the chlorophyll-bearing plants.This brief reference to the algae will suffice for thepresent. The mind are facts to be distinctly kept inthat alg£e contain chlorophyll and have the power ofassimilating inorganic food-substances under the influ-ence of sunlight. Now as to the fungi. Every one has seen toadstool-s, puff-balls, mouldon bread and other organic substances kept in moistand rather dark places, rust on wheat and other cereals,smut on corn, etc.; all of these are fungi. Every onehas heard of bacteria and more or less familiar with isthe role they play in disease some have no doubt ;heard of the importance of bacteria in the manufacture
  43. 43. "WHAT ARE LICHENS ? 27of cheese, in tanning, and in tlie making of butter; allare familiar with processes of fermentation. Thesebacteria, wlietlier indifferent, harmful or beneficial,and the producers of fermentation, belong to thefungi. It is also generally known that fungi are eithersaprophytic or parasitic, that is, they require organicfood obtained from dead or living organisms. In thisthey differ markedly from chlorophyll-bearing plants,as already indicated. Scientists have however deter-mined that fungi were originally chlorophyll-bearingand hence able to assimilate inorganic food in other ;words, fungi are algae which have lost their chlorophylland the functions pertaining thereto. How did theycome to lose their chlorophyll ? The history of thischange is, perhaps, something as follows : Many agesago certain of the algse accidentally came in contactwith higher plants, from which they absorbed some ofthe more soluble food-substances. The association re-duced the amount of work to be done by the chloro-phyll of the parasite ; as the association continued themorphological and physiological changes in the algatended toward a more and more marked parasitism.Every one is familiar with the fact that inactivity ofan organ causes it to become dwarfed and more or lessfunctionless. Chlorophyll became extinct in theseparasitic algae simply because it was functionless : allof the organic food was prepared and supplied by thehost. This change was by no means sudden it re- ;quired many ages to produce the change from brightgreen alga to colorless fungus, or, in other words, to
  44. 44. 28 GUIDE TO THE STUDY OF LICHENS.convert the independent chlorophyll-bearing organisminto a dependent chlorophylless organism. The above is in brief the history of the origin anddevelopment of all vegetable parasites. Even now wecan find all gradations between parasitic states justmaking a beginning, as, for example, some species ofNostoc and Protococcus, and the most highly developedparasitism, as, for example, most of the fungi. Sapro-phytes differ from parasites only in that the originallygreen, hence chlorophyll-bearmg plants, became adaptedto live upon dead organic matter rather than livingorganisms. It must also be kept in mind, that as par-asitism and saprophytism progressed the resultingfungi underwent structural changes so that it is in;many instances practically impossible to recognize theresemblance to any living forms of algae. Scientistsare, however, quite generally agreed that fungi arederived from algae. As a rule, fungi reproduce their kind by means ofvery minute microscopic bodies known as spores. Allof the higher fungi may be divided into two groupsaccording to the manner in which the spores are formedin the one group they are formed on the ends of spe-cialized hyphae, known as hasidia, in the other groupthey are formed within specialized hyphee, known asspore-sacs (Asci). The latter are therefore commonlyknown as sao-fungi. We have to deal with the sac-fungi (Ascomyctes) only. There is, however, oneSouthern lichen ( Cord) which forms basidio-spores. Itis the only exception occurring in the United Statesand is, furthermore, of rare occurrence. Keeping, there-
  45. 45. WHAT ARE LICHENS? 29fore, in mind, that in the discussion of lichens we areconcerned with certain genera of the lower algae be-longing to the Chlorophyceae and the Cyonophyceae, anda division of the higher fungi known as sac-fungi(Ascomycetes), we shall now briefly ex^Jain the phylo-genetic history of a lichen. The origin of one lichen isin all essential respects similar to that of any other, sothat one example will suffice to make clear the originof all lichens. I. THE ORIGIN OF A LICHEN. As to the time when the first lichen was formednothing definite is known. We may, however, safelyconclude that they existed in the geological periodsalong with algae and fungi. We are certain that theycould not have existed before the development of fungi,as explained above ; we also know from what has gonebefore that algae antedate fungi, from which we con-clude that lichens began their existence many ageslater than the first alga? and fungi. From the greatstructural and functional specializations that lichenshave undergone, we must again conclude that they be-gan their existence far back in the geologic ages, thatis, millions of years ago. If we select one of the foliose Parmelias as a type,the hypothetical assumption is that its origin was asfollows : A sac-fungus (Ascomycete) evidently belong-ing to the genus Patella, found it diflicult to maintaina thrifty existence as a saprophyte ; the organic food-supply was no longer adequate to keep up sufiicientenergy to maintain a successful struggle for existence.
  46. 46. 30 GUIDE TO THE STUDY OF LICHENS.The many generations of a life of dependent luxuryhad greatly crippled its energies; functionally it be-came more and more weakened, until finally it couldnot even digest a sufficient quantity of the food alreadyprepared, or, in other words, it no longer possessed suf-ficient vitality to feed itself. In order to regain itslost vitality must again appropriate a larger amount itand better quality of food inorganic food was not ;available, because it had lost its chlorophyll. *If thefungus could, however, prevail upon some chlorophyll-bearing organism to prepare inorganic food-substancesfor its assimilation the problem would be solved that ;is, it must press into its service some plant havingchlorophyll. As already indicated, ordinary parasitismwith higher plants did not suffice: these plants werenot sufficiently adapted to its needs. The fungus wastherefore obliged to cast about for different plants,such as were specially suited to its physiological re-quirements. Splendid opportunities were offered inthe numerous single-celled algae (Protococcus vulgaris),known as " green mould," which everywhere coveredtrees, rocks, etc. The fungus made the attempt andentered into a biological relationship with this alga.It is highly probable that this first relationship was ofa parasitic nature but the fungus soon found that theseminute organisms were scarcely able to supply theextra food materials demanded by the attaching para-site ; the climatic conditions were not sufficiently favor-able, and, furthermore, the alga itself showed a slightpreference toward leading a parasitic life, so that thefungus was considered as a very undesirable intruder.
  47. 47. WHAT ARE LICHENS ? 31If the organisms could in some way form an associa-tion mutually beneficial they would both be enabled tomaintain the struggle for existence. This is whatactuall}- occurred :the two organisms seem to havemade an agreement to assist each other. Whetherthis was a truly altruistic motive, or whether itwas a case of necessity is rather difficult to deter-mine. It was most likely a case of necessity that is, ;the mutualistic association was compulsory in orderto prevent extinction. No matter which was theprime motive, it remains a fact that the alga andfungus finally entered into an association which wasmutually beneficial. This association is very differentfrom parasitism (antagonistic symbiosis), and is recog-nized by scientists as a specialized form of mutualisticsymbiosis, designated as individualism ; the organismswhich enter into the formation of symbiotic associationsareknown as symhionts. The relation of the symbionts under discussion(fungus and alga) was, in a sense, complementary : onesupplied what the other lacked ; there was a harmoni-ous and equable assignment of labor ; each did that forwhich nature had best fitted it. In fact, we may drawtherefrom a wholesome lesson. It should teach us tomake that our life-work for which we are by naturebest fitted so as to accomplish a maximum of goodresults. As to the division of labor in the establishment ofthe lichen, the principal function of the fungus is tosupply protection ; that is, a mechanical function : thechief work of the alga is to perform the function of
  48. 48. 32 GUIDE TO THE STUDY OF LICHENS.assimilation. The fungus gave protection to the algaeby forming a suitable covering to prevent suddenevaporation of moisture ; it also served to conductmoisture and soluble food substances and supplied suit-able mechanical tissues to hold the plant firmly to thesubstratum (trees, soil, rock, etc.). The alga, due toits chlorophyll, assimilated the carbon dioxide (COg)of the air and formed organic compounds for theuse of the fungus as well as for its own use. Themutual adaptations became more and more highlyspecialized, until, after many thousands and, perhaps^millions, of generations, a large foliose lichen was pro-duced, as one of the higher Parmelias. This is, inbrief, the probable history of the j^hylogenesis of Par-melia. At different periods other lower algae enteredinto mutualistic associations with other sac-fungi. Eachprototype developed in different directions, producingnew species and finally, perhaps, distinct genera oflichens. Lichens did, therefore, not spring from asingle ancestral alga and fungus, they are representedby a poly-ancestry. Another remarkable thing is the fact that the agree-ment formed by a given alga and fungus was by nomeans permanent after a long phyletic history a given ;lichen may have changed its alga, that is, the partner-ship was dissolved and another compact entered witha new alga. In many instances a new partner wastaken in and the old was retained, so that we find somelichens with two algal symbionts. From the above, it is evident that lichens arepeculiar plants ; they are the result of the mutualistic
  49. 49. WHAT ARE LICHENS ? 33association of a fungus and an alga, two morphologi-cally distinct organisms. We shall now considersomewhat more in detail the relation of lichens to bothalgae and fungi.II. THE RELATION OF LICHENS TO ALG^ AND FUNGI. In the historical review we have already indicatedthe varied positions given to lichens in the many sys-tems of classification. Shortly before Schwendenerswonderful discoveries lichens were treated as a distinctclass of plants, coequal in systematic importance withfungi, algas and mosses.Schwendener and his fol- .lowers unhesitatingly classified them as fungi. "Why ?Because they looked upon lichens as fungi which wereparasitic upon algie* Reinke, de Bary and others have,however, shown conclusively that it is not a trulyparasitic relationship ; as already indicated, it is anassociation mutually beneficial, known as mutualisticsymbiosis. Schwendeners error was due principallyto the fact that he misinterpreted the relationship andlaid too much upon the spore-bearing structures. stressThere are no more reasons why lichens should beclassed as fungi than as algse. In fact, the eminentscientist, Nageli, classified them as algae and Tucker-man in his earlier writings designates lichens as " aerialalgae." The eminent French lichenologist, Ny lander,had already recognized the double affinity of lichenswithout realizing their true dual nature. In his sys-tem of classification he begins with those lichens mostnearly resembling fungi, gradually proceeding to thehighest foliose and fruticose forms, then forming a
  50. 50. 34 GUIDE TO THE STUDY OF LICHENS.descending series with those most nearly resemblingalgae. From these considerations, it is evident thatthe attempt to classify them either as fungi or algaewill lead to confusion. In agreement with Reinke,Darbishire and others, we have decided to treat lichensas a distinct class. The reasons for so doing will begiven later. In conclusion, we will briefly describe the algaewhich enter into the formation of lichens. The figuresof Plate I represent the algae surrounded by thehyphal network of the fungal symbiont. The fungaltypes cannot be represented, for the simple reasonthat they are not known ; the knowledge that they arederived from some groups of the sac-fungi must sufficefor the present. The general belief is that the fungiwhich originally entered into the formation of lichensno longer exist. There are, however, fungi now liv-ing which resemble the fungal symbionts of certainlichens ; for example, the representatives of the fungalgenus Hysterium closely resemble the fungal symbiontof the lichen-genus Ghraphis. I. Chlorophyce^. — The algae belonging tothis group are distinctly bright-green. The follow-ing are the species which enter into the formation oflichens, given in the order of the frequency of occur-rence. 1. Cystococcus humicola. This is a unicellular algaoccurring in far the greater number of lichens. Thecells are spherical. (Fig. 1.) 2. Chroolepus umhrina. This alga forms short
  51. 51. WHAT ARE LICHENS? 35brandling cliains of rather oblong irregular cells bear-ing brownish substances known as pyrenoid bodies.(Fig. 2.) 3. Pleurococcus vulgaris. A single-celled alga ofrather irregular outline. It sometimes has a bluishtinge. (Fig. 8.) 4 Glceocapsa polydermatica. This is also a single-celled alga. It differs from the preceding in that eachcell is enclosed by a thick, transparent, gelatinous mem-brane. (Fig. 4.) 5. Dactylococcus infusionum. A single-celled alga.The cells are comparatively small and regularly ellipti-cal ; they are usually associated in colonies of eight orten cells. (Fig. 7.) II. Cyanophyce^. — The alg* of this group differfrom the chlorophyce^e in their blue-green color. 1. Nostoc lichenoides. This alga occurs in chainsof rather small cells. Each chain contains one, rarelymore, larger cell known as a heterocyst. Each chainis enclosed by a gelatinous substance. (Fig. 3.) 2. Rivularia nitida. This alga o also occurs inchains, but its cells are irregular in form. Gelatinoussubstance present. (Fig. 5.) S. Poly coccus punctiformis. Tlie cells of this algaare elliptical and occur in colonies enclosed by a com-mon covering. (Fig. 6.) 4. Sirosiphon puhinatus. This is a many-celledbranching alga of sufficient size to be seen by thenaked eye. It occurs in the lichen-genus Ephebe.(Fig. 9.)
  52. 52. 36 GUIDE TO THE STUDY OF LICHENS. These brief references to the algae, with the accom-panying illustrations, will suffice at present, as theywill again be mentioned in the discussion of lichen-genera. III. LICHENS AS MORPHOLOGICAL UNITS. We shall now briefly summarize those characteristicswhich distinguish lichens from other plants, fungi andalgae in particular. This is very necessary in thepresent state of our knowledge of lichens, as the influ-ence of Schwendeners teachings is as yet very stronglyfelt. Lichens macroscopically considered present such apeculiar appearance that the most superficial observeris led to believe that they form a group by themselves.They occur in places where neither alga nor funguscould exist alone. They have wonderful powers ofresisting extremes of temperature ; freezing only checkstheir growth; a temperature of — 40° C. does not killthem. They will resist a temperature of 60° C. foran hour or more. They can tide over periods of dry-ness which would invariably be fatal to either alga orfungus if existing alone. The two symbionts form a microcosmos which is en-abled to perform the life-functions originally inherentin both, and, in addition, the lichen has acquired newstructural and functional characters during its phyl-ogeny. The morphological adaptations are primarilyfor the furtherance of the function of assimilation,while among fungi the structural adaptations are pri-marily for the furtherance of the function of reproduc-
  53. 53. WHAT ARE LICHENS r* 37tion. The method of reproduction in lichens is whollydifferent from that of fungi as well as algae. It is,however, true that the spores of lichens have a closemorphological resemblance to the spores of certainfungi, but functionally they differ widely. The sporesof fungi can develop into new spore-producing in-dividuals, while the spores of lichens cannot producenew lichens unless associated with the essential algae,which proves that the fungal symbiont can no longermature independently. Some of the lichen-algae havebeen induced to exist independently, but it is evidentthat some cannot. Lichen-spores are simply thefunctionally degenerate reproductive organs of theirfungal ancestors. As already indicated, fungi are essentially parasiticand saprophytic. Lichens have partially or almostwholly lost the saprophytic and parasitic function andhave acquired the power of converting inorganic sub-stances into organic compounds. The thallus of lichensis structurally and functionally comparable to the leafof higher plants ; fungi have no thallus, nor do theyhave any functional resemblance to the leaves of higherplants. Lichens also contain chemical compounds not foundin fungi or algae. Among these, lichenin (lichen-starch)is the most important ; others are various acids (ever-nic, cetraric, etc.) and bitter extracts, coloring sub-stances, and other compounds as yet not well known. The typical reproductive organs of lichens are thesoredia. These are in reality miniature thalli espe-cially adapted to serve as propagative organs. They
  54. 54. B8 GUIDE TO THE STUDY OF LICHEKS.are formed of the elements of both symbionts and cantherefore develop into a new lichen. Their structureand function will be more fully described elsewhere.Lichens are also more long lived than fungi. Themajority of fungi terminate existence with the matura-tion of the spores, while most lichens have an indefin-itely prolonged existence. Some of the Cladonicis, forexample, may live hundreds of years ; the apical portioncontinues to grow, while the basal portion dies away. Sufficient reasons have been given to show thatlichens are neither fungi nor algae ; they must there-fore be treated as a distinct class of plants. Othercharacters peculiar to lichens will be mentioned later.
  55. 55. MORPHOLOGY AND PHYSIOLOGY. 39 SECTION IV. THE MORPHOLOGY AND PHYSIOLOGY OF LICHENS. We have already explained, in a general way, themorphological structure and the functional activitiesof lichens. We shall now enter into a somewhat morespecial comparison of the different lichen-forms. Thisis necessary to a better understanding of the relativefunctional activities of lichens and their tendency inthe scale of evolution. We will find that the higherlichens are more highly specialized as chlorophyll-bearing organisms, and tluit the evolutionary ten-dency is away from tlie forms resembling fungi. Wewill find that there is a reduction in the spore-produc-ing function, accompanied by an increase in the assim-ilative function. I. THE THALLUS. The thallus of lichens is the purely vegetative portionof the plant. It performs the function of assimilation,and in phenomena of growth are actively mani- it thefest. comparable to the vegetative portion of It isother cryptogams, such as mosses and liverworts. Inits gross appearance and general texture, it is, how-ever, very characteristic ; so that a very casual ac-quaintance with lichens enables one to distinguishthem from all other thallophytes, as the lower flower-less plants are technically known.
  56. 56. 40 GUIDE TO THE STUDY OF LICHENS. From what has already been said of lichens, thereader knows that the thallus is functionally whollydifferent from the vegetative portion of fungi. Themain difference may be stated as follows In fungi :the structural development and arrangement of tissue-elements, of the vegetative portion, is for the specialpurpose of furthering the function of reproduction,that is, to supply a suitable structural arrangementfor the maturation and distribution of the spores. Inlichens the structural development and arrangementof the tissue-elements is for the special purpose offurthering the function of assimilation. Structurally and functionally, the thallus of lichensis also analogous to a foliage leaf of higher plants.This becomes apparent on comparing vertical sections.The upper and lower cortical layers of the thallus arefunctionally analogous to the upper and lower epider-mis of the leaf ; the algal layer of the thallus to thepalisade tissue of the leaf ; the medullary tissue of thethallus to the spongy tissue of the leaf. The analogyis, in fact, very striking, particularly between foliosethalli and the ordinary flattened foliage leaves. Fru-ticose thalli are analogous to leaves with " isolateralor "centric" structure. Crustose thalli are in realityrudimentary foliose thalli, and are, therefore, remotelyanalogous to ordinary foliage leaves. For practical purposes, the thalli of all lichens maybe divided into three types or kinds, namely, crustose,foliose, and fruticose. Their structural differences areas follows
  57. 57. MORPHOLOGY AND PHYSIOLOGY. 41 1. The Crustose Type. This thallus occurs in the lower lichens, that is, inthose in which the evolutionary specializations aslichens are not yet highly marked. In its simplestform it consists merely of a network of hyphae inwhich are suspended a few algas ; it may occur on thesubstratum, or wholly, or partially, beneath its sur-face. There are no distinct layers, in fact, in manyinstances it is almost impossible to detect any thalluswhatever. Such rudimentary thalli occur in the lowerspecies of Calicium^ Pyrenula, Trypethelium, Xylo-grapha, Arthonia and other genera. The higher crustose thalli are quite thick, as in Le-canora, Pertusaria, the southern representatives ofGhapkis, in Pceomyces, and other genera. The sur-face is often warty or the entire thallus is marked offinto many-sided areas or areoles and is therefore spokenof as areolate. In higher crustose thalli we find thetissue-elements arranged into distinct layers, as seenin a vertical section. The upper layer consists ofhyphae and constitutes a protective covering for thelayer of algae just beneath. The algje are inclosed byspecialized branches of hyphse, spoken of as haustoria.Below the algae occurs another layer of hyphae whichattach the thallus to the substratum and assists in tak-ing up soluble food-substances. The hyphae formingthe upper layer, the haustoria, and the lower layer arecontinuous, and are part of the same hyphal tissue.In many instances the upper layer becomes more orless distinctly cortical, thus resembling the ui)perlayer of foliose thalli. In fact, very often it

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