Bryophytes order sphagnales

Bryophytes order sphagnales

• 1.
  Sphagnales Bryophytes
• 2.
  Bog mosses orpeat mosses  Commonly c/as ‘bog mosses or peat mosses’  Bog: Badly drained permanently wet land with high rainfall  Common in upland and waste areas of temperature regions  Peat: Partially decomposed plant material  Common in areas with poor drainage Department of Botany JES College Jalna
• 3.
  Distribution and Habitat 3 Only genus – Sphagnum, a bog moss  Some called as turf moss  Cosmopolitan – north & south tropics, through temperate regions extending to sub-arctic and sub-antarctic regions  Dense masses in ponds, lakes which contain little amount of lime  In cooler cliamtes – dominates the vegetation  350 Species  > 20 in India Department of Botany JES College Jalna
• 4.
  Distribution and Habitat 4 Grows in water with pH range from 3.7 to 4.9  Size – few inches to 7 inches  Perennial moss: Older parts die regularly and in combination with the remains of other surrounding plants, form a compact mass k/as peat  Since, Peat former – great commercial importance Department of Botany JES College Jalna
• 5.
  Mature Gametophyte 5  Erect,branched – differentiated into stem & leaves  Rhizoids – colourless, survive for a short time  Apex – posses no. of densely crowded short branches called ‘coma’  Posteriorly, branches arise in tufts in axil of every fourth leaf  Each tuft – 3 to 8 branches  Divergent branches: Short, stout, outward & upward  Drooping or flagelliform branches: Hang downward, close & around the stem (absent in submerged forms) Department of Botany JES College Jalna
• 6.
  Mature Gametophyte 6  Sometimes,one branch in tuft grows & develops into an apical cluster of branches as the main stem  This is called ‘innovation’  When separates from main plant – grows into an independent plant  The first formed lvs .are 3-ranked  Arrangement turns to 2/5 in the later stages  Exceptional feature of Sphagnum – absence of midrib Department of Botany JES College Jalna
• 7.
  Reproduction 7  Vegetative reproduction Innovations  Some multiply by primary protonema :- Few thalloidal cells of primary protonema become meristematic & forms multicellular filament This develops into a thallus-like, flat secondary protonema • Sexual reproduction • Both monoeciuos and dioecious species • Antheridia – on Antheridial or Male branches • Archegonia – on Archegonial or Female branches Department of Botany JES College Jalna
• 8.
  Reproduction 8  Antheridial orMale Branches  Catkin-like small structures  Arranged spirally or in straight rows on main axis  Possess many small, coloured lvs - Yellow, brown or reddish  Axil of each leaf – antheridial branch develops antheridium – acropetally Department of Botany JES College Jalna
• 9.
  Reproduction 9  Mature Antheridium Long stalk & globular body  Stalk – 2 to 4 rows of cells  Single layered sterile jacket enclosing androcyte cells  Androcyte – metamorphoses into biflagellate, unicellular, uninucleate antherozoid  Antheridium – dehisces by several irregular lobes or valves at the apex Department of Botany JES College Jalna
• 10.
  Reproduction 10  Archegonial Branches Shorter than antheridial branches  Bud-like strcutures bearing single or 2-5 archegonia surrounded by lvs.  Lvs – green & larger than lvs of vegetative branches  These are c/as ‘perichaetium’  Primary archegonium : develops from apical cell  Secondary archegonia : develop from derivatives of apical cell Department of Botany JES College Jalna
• 11.
  Reproduction 11  Mature Archegonium Long stalk, twisted neck & a massive venter  Neck jacket : 2-3 celled thick in base & middle parts  8 or more cover cells at apical part  Neck cavity: 8-10 neck canal cells  Venter: single venter canal cell and an egg Department of Botany JES College Jalna
• 12.
  Reproduction 12  Mature Sporophyte Contains foot, seta & capsule  Foot : Parenchymatous; bulbous or cylindrical body; haustorial in function  Seta: ill-developed; inconspicuous and has very narrow structure  Capsule: Well-developed, quite conspicuous & spherical  Dark-brown or black coloured  Has 2-7 layered wall  Outer layer – epidermis with several nonfunctional stomata Department of Botany JES College Jalna
• 13.
  Reproduction 13  Mature Sporophyte Capsule wall with chloroplasts  Operculum : at apical part of the capsule (It is a circular, biconvex disc-shaped structure)  Annulus : circular groove of thin-walled cells separates the operculum from capsule • Columella : central part of the capsule; made up of sterile cells • Dome-shaped arch of fertile sporogenous tissue is present over the columella • Calyptra & perichaetium surround the sporophyte in young conditions Department of Botany JES College Jalna
• 14.
  Reproduction 14  Mature Sporophyte •At maturity, axis of archegonial branch elongates and capsule comes out of calyptra & perichaetium • The leafless, elongated axis of the archegonial branch, at the base of sporophyte is c/as pseudopodium  It is mainly a post-fertilization devt • A sac-like structures from the distal end of the pseudopodium & basal part of the calyptra, is k/as vaginula • Foot remains embedded in the vaginulla Department of Botany JES College Jalna
• 15.
  Reproduction 15  Dehiscence ofcapsule • Capsule dehisces by ‘air-gun mechanism’ • Due to heat of the sunny day, columella & the capsule wall become dry and get shrivelled • It develops air space under the spore sac • Capsule changes its shape from spherical to cylindrical • Air inside the capsule gets compressed, and a pressure also develops inside the capsule • Due to this, operculum breaks off at the aanulus • Spore sac ruptures and the spores are blown to a height of several centimetres Department of Botany JES College Jalna