Gymnosperms.pptx

Gymnosperms.pptx

• 1.
  GYMNOSPERMS MORPHOLOGY, ANATOMYAND REPRODUCTIVE STRUCTURE
• 2.
  INTRODUCTION  The Gymnospermsare a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes.  The term "gymnosperm" comes from word gymnospermos, meaning "naked seeds", after the unenclosed condition of their seeds (called ovules in their unfertilized state).  Gymnosperm seeds develop generally on the surface of scale- or leaf-like appendages of cones.  జిమ్నోస్పెర్మ్లు విత్తనాలు ఉత్ెత్తత చేస్ే మొక్కల సమూహం, ఇవి కోనిఫపర్మ్ ు , స్పైకాడ్ల ు , జింగో, మరియు గెనెట్ైైటు ను క్లిగి ఉంటాయి.  పదం "జిమ్నోస్పెర్మ్" పదం జిమ్నోస్పెరో్స్ నుండి వచ్చంది, దీని అర్మధం "నగ్ో విత్తనాలు", వారి గింజల యొక్క ఎడ్తెగ్ని స్థిత్తలో (వారి పరాధీన స్థిత్తలో ovules అని పథలుస్ా త ర్మ్) త్ర్మ్వాత్.  జిమ్నోస్పెర్మ్ విత్తనాలు కొలత్ యొక్క ఉపరిత్లంపపై స్ాధార్మణంగా అభివృదిధ చెందుతాయి- లేదా శంఖుల వంటి ఆక్ు వంటివి.
• 3.
  Diversity and Origin There are between 700 and 900 extant* or currently living species of Gymnosperms.  It is widely accepted that the gymnosperms originated in the late Carboniferous Period. Early characteristics of seed plants were evident in fossil progymnosperms of the late Devonian period around 380 million years ago.  Extant is a term commonly used in biology to refer to taxa (such as species, genera or families) that are still in existence (living). The term extant contrasts with extinct.  700 మరియు 900 మనుగ్డ్లో * లేదా జిమ్నోస్పెర్మ్్ యొక్క పరసు త త్ జాత్ులు ఉనాోయి. జిమ్నోస్పెర్మ్లు చ్వరి కారబొనిఫపర్మస్ కాలం నుంచ్ పుటట ు కొచాచయని విసతృత్ంగా అంగీక్రించార్మ్. 380 మిలియన్ సంవత్సరాల కరిత్ం సుమార్మ్ చ్వరి దేవొనియన్ కాలపు శిలాజ ప్రర జిమ్నోస్పెర్మలులో విత్తన మొక్కల ప్ా ర ర్మంభ లక్షణాలు సెష్ుంగా క్నిపథసు త నాోయి. * ఉనికరలో ఉనో జీవనశైలిని సూచ్సు త నో జీవజాత్తలో (స్ాధార్మణంగా జాత్ులు, జాత్త లేదా క్ుటటంబాలు) సూచ్ంచడానికర స్ాధార్మణంగా ఉపయోగించే పదం. ఈ పదానిో మనుగ్డ్లో వయతాయసం క్లిగి ఉంది
• 5.
  Diversity and Origin Conifers are by far the most abundant extant group of gymnosperms with six to eight families, with a total of 65- 70 genera and 600-630 species (696 accepted names).  Conifers are woody plants and most are evergreens.  The leaves of many conifers are long, thin and needle-like with a waxy coating, others species, including most Cupressaceae and some Podocarpaceae, have flat, triangular scale-like leaves.  Cycads are the next most abundant group of gymnosperms, with about 130 species. The other extant groups are the 75 - 80 species of Gnetales and one species of Ginkgo.
• 6.
  • 60-70 జాతిమరియు 600-630 జాతులు (696 ఆమోదించబడిన పేర్ల ు ) మొత్ త ిం ఆర్ల నిండి ఎనిమిద కుటింబాలు కలిగిన జిమోోస్పెర్లలు చాలా ఎకుువగా ఉన్నోయి. • కోనిఫర్ల ు అడవులు మరియు చాలా సత్త్హరితాలతో ఉింటాయి. అనేక కోనిఫెర్ ు ఆకుల పొడవాటి, సనోని మరియు సూద వింటిద ఒక మ ై నపు పూత్తో, చాలామింద కాప్ర ె స్సీయే మరియు కొనిో పోడోకార్పెస్సతో సహా ఇత్ర్ జాతులు ఫ్ల ు ట్, తి ి భుజాకార్-స్థ ా యి ఆకులు కలిగి ఉింటాయి. • 130 ర్కాల జాతులు కలిగిన జిమోోస్పెర్ల్ యొకు త్దుపరి అత్యింత్ విస్థ త ర్మ ై న బ ిందిం స్ప ై కాడ్ల ు . ఇత్ర్ మనగడలో ఉనో గ్ర ూ పులు 75 - 80 జాతి జీటాలేలీ్ మరియు జిింగో యొకు ఒక జాతి.
• 8.
  Characteristics of Gymnosperms There exist a set of standard feature or characteristics that help to identify gymnosperms. Here are some of the peculiar characteristics of gymnosperms  Gymnosperms do not have an outer-covering or shell around their seeds.  Gymnosperms are heterosporous which means that they produce different male and female spores. The microspores develop into pollen grains and the megaspores are in an ovule.  ప్ా ర మాణిక్ లక్షణం లేదా జిమ్నోస్పెర్మలును గ్ురితంచడానికర సహాయపడే లక్షణాల సమిత్త ఉనికరలో ఉంది. జిమ్నోస్పెర్మ్ యొక్క విచ్త్ర లక్షణాలు కొనిో ఇక్కడ్ ఉనాోయి జిమ్నోస్పెర్మ్లు వారి విత్తనాల చుటట ు బయటి-క్వరింగ్ లేదా షపల్ లేదు. జిమ్నోస్పెర్మ్లు హేట్రోస్ర ెరోస్, అంటే అవి వివిధ మగ్ మరియు ఆడ్ స్ర ెర్ము్ును ఉత్ెత్తత చేస్ా త యి. మైకోిస్ప ెర్మలు పుప్ప ెడి గింజలుగా అభివృదిధ చెందుతాయి మరియు మగాస్ర ెర్మస ఒక్ అండాకార్మంలో ఉంటాయి.
• 9.
  Characteristics of Gymnosperms Gymnosperms produce cones.  Gymnosperms do not bear fruits.  Gymnosperms propagate via wind pollination.  The adult plant body is a sporophyte. It is represented by a perennial, evergreen, woody plant. Most of them are trees and some are shrubs. There are no herbs.  Pinus as well as other conifers are evergreen trees. They have monopodial growth represented by one main axis. As the axis grows taller it increases in diameter due to secondary growth. Stem branches are of two types: 1. Long shoots or branches of unlimited growth. 2. Dwarf shoots or branches of limited growth
• 10.
  Sporophyte: The asexualand usually diploid phase, producing spores from which the gametophyte arise. Monoxylic: Wood is not compact due to the presence of well – developed pith and cortex and broad medullary rays. Pycnoxylic: Wood is compact as pith and cortex are reduced and medullary rays are narrow. Sporophylls: Sporangia are formed on specialised leaves, known as sporophylls.
• 11.
  CYCADALES: CYCAS  Themembers of this order are commonly known as cycads. They originated from the seed ferns. i.e., Cycadofilicales, towards the end of Carboniferous periods and formed a dominant vegetation during the Triassic periods of Mesozoic era.  The order includes eleven living genera and about 100 species. They are usually woody trees except Zamia pygmaea.  The stem is mostly unbranched and is covered by persistent leaf bases. The leaves are arranged in whorls at the apex of the stem ; they are pinnately compound.  The wood is monoxylic. The micro-and megasporophylls usually from male and female strobili.
• 12.
  CYCAS Systematic Position Division - Class- Order - Family- Cycadophyta Cycadopsida Cycadales Cycadaceae  Cycas is the most widely distributed genus of the order Cycadales. There are about 20 species which occurs in wild state in China, Japan, Australia, Africa, Burma andIndia.  Four species of Cycas – C. circinalis , C. pectinata, C. rumphii and C. beddomei – occurs in natural state in India, Chiefly in Assam, Orissa, Meghalya, Andaman and Nicobar Islands, karnataka and Tamil Nadu. C. revoluta and C. siamensis are widely grown in gardens.
• 13.
   Cycas pectinata:It is mainly distributed in Nepal, Sikkim, hills in Bihar Assam and Chittagong. The plant is 2- 3.5m in height with a crown of leaves at the top of the unbranched stem. The leaves are 1.5 – 2 m long with flat and linear leaflets. The male cones are cylindric- ovoid and about 40 cm long. Each megasporophyll has 4-6 ovules.  C. revoluta: It is a native of China and Southern Japan and is widely cultivated as an ornamental plant in India. The plant is 1.5- 2 m in height and has revolute leaflets. The male cones are cylindrical or ovoid- oblong. The tomentose megasporophyll bears 2- 4 ovules.
• 14.
   C. beddomei:It occurs in wild state in Cuddapah district of Andhra Pradesh. It has a dwarf trunk, only up to 40 cm high, and strongly revolute leaflets. The rachis is without spines, but the basal part of the rachis is covered with tufted hairs. The male cones are oblong- ovoid, and the megasporophylls are ovate- lanceolate with linear teeth.  C. circinalis: It is common in the western parts of Peninsular India, Western Ghats and Orissa hills. It is 1.5- 3 m in height. The leaf has more than 160 pairs of flat and acuminate leaflets. The male cones are cylindric- ovoid and the tomentose megasporophyll bears up to 12 ovules.
• 15.
   C. rumphii:This species occurs in Andaman and Nicobar Islands. The plant is 1.5- 4 m high with 1-2 m long leaves, each with 50-100 pairs of leaflets. The male cones are ellipsoidal and stalked, and the megasporophyll is linear- ovate and 6-10 ovulate.  C. siamensis: it is widely distributed in Burma, China, Thailand and Yunnan. In India, It is grown as an ornamental plant. The plant is about 3 m tall with nearly a meter long leaves. The male cones are ovoid- oblong, and the megasporophyll has two ovules.
• 16.
  SPOROPHYTE  Plants arelow and palm-like , height 4-8 feet.  Tallest species, C. media – up to 20 feet high  Stem unbranched , columnar and covered with persistent leaf bases.  Leaf segment remains circinnately involute within the bud– leaves dimorphic.  Female reproductive structures–the megasporophylls are not aggregated in cones.  Ovules (2 or more) borne on the lower margins in ascending order
• 17.
  External Morphology Stem- Cycasplant shows tuberous stem when young , becoming columnar and unbranched later. Leaf– Shoot apex is protected by a rosette of brown scale leaves. Plant grows very slowly adding a new crown of leaves every 1 or 2 years , alternating with crown of scale leaves.
• 19.
  External Morphology The pinnatelycompound megaphyllous leaves have 80-100 pairs of leaflets arranged on the rachis Leaf base is rhomboidal in shape and attaches the leaf transversely to the stem The leaflets are thick , leathery in texture, ovate or lanceolate in shape & photosynthetic in function.
• 20.
  External Morphology  Scaleleaves are very small , rough and dry , triangular in shape and brown in colour , thickly coated.  Root is of two types – normal and coralloid.  Normal tap-roots grow from the radicle deep inside the soil giving out lateral branches  Some of the lateral roots grow apogeotropically towards the surface of soil and branch dichotomously  These roots are short , thick and swollen at the tips.
• 22.
  External Morphology  Themuch branched mass appears like a coral on the soil surface hence called coralloid roots  Do not bear root caps  The cluster has lenticel like apertures  Become infested by N2 (cyanobacteria); bacteria fixed blue-green & diatomse algae eg. Nostocpunctiforme,Anabaenacycadacaerum  Symbiotic relationship thus established
• 23.
  Anatomy Root  Young rootshows typical structure like that of a dicotyledonous root  Outer most layer , epiblema , encloses the parenchymatous cortex interspersed with tannin cells and mucilage canals  Endodermis with casparian thickenings  Pericycle is multilayered with thin cell shaving starch grains  Vascular tissue within is typically radial  Roots usually diarch to tetraarch , rarely polyarch  Vessels absent in vascular tissue  Pith reduced or absent
• 24.
  Anatomy –Root  Olderroots show secondary growth  Cambial ring is initiated between xylem & phloem and completed by differentiation in inner layer of pericycle adjacent to protoxylem elements  These cambial cells are meristematic and add secondary xylem on the inside and secondary phloem towards cortex  Along side phellogen (cork cambuim) develops in outer most layer of cortex below the epidermis  This produces dead cork cells (phellem) towards outer side and living secondary cortex cells (phelloderm) on the inside.  Lenticels are developed in old roots
• 25.
  Anatomy –Root Coralloid Roots Hasadditional algal zone in the cortex Cells of algal zone palisade like and form the middle cortex
• 26.
  Anatomy –Stem Stem  Showirregular outline due to the presence of leaf bases , therefore epidermis is not a continuous layer  Broad cortex is traversed by simple and girdle leaf traces  Numerous mucilage canals, starch grains also present vascular tissue  Narrow zone of having open, endarch vascular bundles arranged in a ring and separated from each other by wide medullary rays  Pith is large, parenchymatous shaving mucilage canals and starch grains
• 27.
  Anatomy –Stem and wide Old stem of Cycas shows secondary growth  Wood manoxylic type with scanty xylem medullary rays
• 28.
  Anatomy –Rachis Rachis ofCycas Woody and thick Hypodermis sclerenchymatous Characteristic feature is omega shaped (Ω) outline of the numerous vascular bundles Each bundle has sclerenchymatous bundle sheath and is open , collateral.
• 29.
  Anatomy –Leaflet Cycas Leaflet Leaflet is thickly cutinized and leathery  Possesses all xerophytic characters  Sunken stomata and thickened hypodermis present  Well developed palisade layer in mesophyll  Between the palisade and lower mesophyll layers , there are transversely running long colourless cells in 3-4 layers extending from mid- rib to near leaf margin  These constitute the transfusion tissue  Mid-rib bundle consists of abroad triangular centripetal xylem and two small patches of centrifugal xylem–thus dipoxylic  Phloem abaxially placed
• 30.
  T.S of CycasLeaflets
• 31.
  Reproduction –Vegetative  V egetativereproduction is by means of bulbils  Develop in crevices of scale leaves and leaf bases at the basal part of an old stem  Produces new plant on detachment
• 32.
  Reproduction –Sexual  Strictlydioecious plant  Male plants are rare  Male strobilus or cone borne singly at the apex of the trunk  Apical shoot apex utilized in the development of male cone, hence branching sympodial  Cone shortly stalked & large (upto 50 cm length or more)  Numerous micro- sporophylls spirally arranged around the central axis  Each micro- sporophyll is narrow below and broad above terminating into projection–the apoplysis  Microsporangia confined to abaxial (lower) surface  Usually present in sori– each with 2- 6 sporangia  They contain a large number of haploid microspores (pollen grains) STROBILUS
• 34.
  Female Reproductive Structures Female plant do not produce definite cones  A whorl of spirally arranged megasporophylls arise around the shortapex  Each megasporophyll resembles thefoliageleafandapproximately 10-23cms.long  Lower petiolar part bears the naked ovules on the margins
• 35.
  Ovule Structure  Largestovule (6 cms. X 4 cms.) seen in C. circinalis  Ovules are orthotropous, sessile , ovoid or spherical in shape and unitegmic.  The thick integument is differentiated in three layers- outer and inner fleshy layers , middle stony.  The integument remains fused in side with nucellar tissue except at the position where it forms the micropylar opening.  Ovule is well supplied with vascular bundles.
• 36.
  Megasporangium The megaspore developsin the nucellus by meiotic division and goes on to form female gametophyte tissue. 2- 3 archegonia are formed in this haploid tissue which is food laden. Egg cell in the venter undergoes fertilization of archegonia , by the motile spermatozoid forming diploid zygote.
• 37.
  Pollination -Development ofmale gametophyte after pollination  The pollen grains are carried by wind (Anemophily) and caught by pollination drop secreted by ovule. Pollination is direct.  The pollination drop is dehydrated and the pollen grains are sucked in to the pollen chamber.  Pollen grains take rest for sometime in the pollen chamber.
• 39.
   During thegermination of pollen grain the exine is ruptured and the inner intine comes out in the form a tube like structure known as pollen tube.  At this time the generative cell divides and forms a larger, upper body cell and smaller , lower stalk cell.  The pollen tube acts as haustorium to absorb food materials from the nucellus besides as sperm carrier.  The body cell divides and forms two naked , top shaped , motile , multiciliated antherozoids. The cilia are in 4–5 spirals.  The male gametes of Cycas are 180–210 μ in size and largest in the plant kingdom.  The pollen tube apex is ruptured and the male gametes are released into the archegonial chamber.  Presence of multiciliated male gametes is the fern character shown by Cycas male gametophyte
• 40.
  Young Sporophyte–Embryo Embryo developmentis meroblastic. Pro embryo shows upper haustorial part, middle elongating suspensors and the basal meristematic embryonal region.
• 41.
  LIFE CYCLE OFGYMNOSPERMS
• 42.
  CONIFEROPHYTA: PINUS  Thisis the largest division of gymnosperms, which includes Pines, Yews, Spruces, Junipers, Cedars and many more plants  With approximately 588 living species, this is the most diverse and by far the most ecologically and economically important gymnosperm group  They are usually long, branched and evergreen trees. The branches usually dimorphic and bear needle like, linear or lanceolate leaves.  The wood is pycnoxylic, characterised by the presence of resin canals.  The micro and megasporophylls form compact cones. The male gametes are non- motile and the fertilization is siphonogamous.
• 43.
  PINUS Systematic Position Division -Coniferophyta Class- Coniferopsida Order- Coniferales Family- Pinaceae Genus- Pinus  Pinus is one of the most important taxon of the order conoiferals, is represented by about 105 species, distributed throughout the northern hemisphere.  Five species of Pinus occurs in the Indian sub continent of these four species are confined to the north east and north west Himalayan regions.
• 44.
  1. Pinus roxburghii:Pinus roxburghii (known as chir pine) is a species of pine. Pinus roxburghii is a large tree reaching 30– 50 m (98–164 ft) with a trunk diameter of up to 2 m (6.6 ft), exceptionally 3 m (10 ft). The bark is red-brown, thick and deeply fissured at the base of the trunk, thinner and flaky in the upper crown. The leaves are needle-like, in fascicles of three, very slender, 20–35 cm (7.9–13.8 in) long, and distinctly yellowish green. 2. Pinus wallichiana: The leaves ("needles") are in fascicles (bundles) of five and are 12–18 cm long. They are noted for being flexible along their length, and often droop gracefully. The cones are long and slender, 16–32 cm, yellow-buff when mature, with thin scales; the seeds are 5–6 mm long with a 20–30 mm wing.
• 45.
  3. Pinus gerardiana:This species common in Kashmir and Kinnaur district. The trees are 10-20 m tall with usually deep, wide and open crowns with long, erect branches. However, crowns are narrower and shallower in dense forests. The leaves are needle-like, in fascicles of 3, 6–10 cm long, spreading stiffly, glossy green on the outer surface, with blue- green stomatal lines on the inner face; the sheaths falling in the first year. 4. Pinus merkusii: This species occurs on the hillock in East Bengal at an altitude of 150- 600 meter . The plant is only 3-4 meters high. There are two needles in each foliar spur.
• 46.
  5. Pinus insularis:This species is widely distributed in khasya regions of Assam at an altitude of 700- 1850 meters. The plant attain a height of about 30 meters and the foliar spurs are trifoliate.
• 47.
  Sporophytic Plant Body Adultplants are tall trees up to 200 feet in height Perennial, xerophytic plants appearing pyramidal or conical due to radial branching Branches are dimorphic – long shoots and dwarf shoots (spurs) Leaves are dimorphic – Scale leaves and green acicular leaves Male and female cones present on the same plant, hence monoecious
• 48.
  External Morphology –Stem Erect, tall, cylindrical, woody and branched Branching monopodial and excurrent Lower branches longer and horizontal giving the conical shape to the plant
• 49.
  Branches of unlimitedgrowth are the long shoots Arranged spirally around the main trunk Bear scale leaves and dwarf shoots in axils of scale leaves Branches of limited growth or dwarf shoot lacks apical bud Possess 8-10 spirally arranged scale leaves terminating into 1-5 needle like foliage leaves at apex
• 50.
  External Morphology –Leaves  Scale leaves thin, brown and small  Main function is to protect young buds & conserve water around the branches  Foliage leaves are long & acicular (needle like)  Remains green for a number of years (3-10 yrs) hence plants are evergreen  No. of needles per spur varies from 1-5 with species (monofoliar to pentafoliar)
• 51.
  External Morphology –Root Plant possesses tap root Elongated structure with strong lateral branches Root-hairs scanty; function taken up by ectotrophic mycorrhiza (fungus roots) It is symbiotic association of fungal mycelium on the root’s surface Helps in absorption of nutrients & protection from pathogens Fungal species identified are Rhizopogon, Amanita, Boletus, Entoloma, etc. – mostly members of Basidiomycetes
• 52.
  Anatomy – Root Resembles typical dicotyledonous root.  Pili ferous epiblema bear unicellular root hair (seen only in young roots) parenchymatous cortex and pericycle layers  Broad follows  Endodermis seen next  V ascular tissue is radially arranged in 2-6 groups of xylem and phloem  This tissue lacks true vessels and companion cells  Resin canals present in xylem patch making it Y-shaped  Old roots show secondary growth
• 53.
  Anatomy – Stem Typically dicotyledonous stem  Cuticularized epidermis encloses the lignified sclerechymatous hypodermallayerbelow  Inner cortex is thin walled parenchyma containing chloroplasts and resincanals  Vascular bundles are conjoint, collateral, endarch , open and form a ring  Medullary rays are narrow  Vessels in xylem and companion cellsinphloemareabsent
• 54.
  Secondary growth instem  Ring of vascular cambium develops  Remains active each year forming spring wood & autumn wood – annual rings  Important in dendrology for estimation of the age of the plant  Secondary medullary rays usually uniseriate  Pinus wood is dense and massive with few parenchyma cells – pycnoxylic  Cork cambium (phellogen) formed in outer cortical layer  Forms secondary cortical cells (phelloderm) towards inner side and cork (phellem) on outer side
• 55.
  Anatomy – Leaf Xeromorphic P .longifolia is trifoliar; so the needle shows triangular outline Outermost epidermal layer has thick-walled cells which are cuticularized Stomata are sunken Hypodermisissclerenchymatous
• 56.
  Mesophyll not differentiatedfurther These cells have peg-like in foldings of cellulose projecting in their cavities Have a large number of chloroplasts & starch grains Resin canals with secretory tissue present Two vascular bundles with conjoint tissue present in the middle
• 57.
  REPRODUCTION Takes place bymeans of spores – microspores (male) and (female). The plants are megaspores therefore heterosporous The male and female cones occur on the same plant, but different branches i.e. monoecious
• 58.
  Male cones (Staminatecones)  Borne on the lower branches in the axils of scale leaves.  Appear in the month of January (in plains) and March (in hills) reaching maturity within 2-3 months.  Can be seen in clusters just behind the shoot – apex.
• 59.
  Male cones (Staminatecones) Each cone has 60-100 spirally arranged microsporophylls Two microsporangia are present on the underside of each microsporophyll Development of microsporangium is eusporangiatetype Within the microsporangium, the microspore mother cells undergo meiotic divisions to form haploid microspores
• 60.
  Microspore (Pollen grain) It is surrounded by a 3-layered wall  Exine heavily cuticularized on one side of the microspore  Middle layer (exo-intine) projected outwards into two large balloon-like air sacs or wings  Inner layer (intine) is very thin  On maturation the spores germinate in situ. Hence, early gametophytic development is precocious  At the time of dehiscence, huge quantities of microspores form yellow clouds around the pine forests. It’s called the “Shower of sulphur dust”
• 61.
  Female cone (Ovulatecone)  Borne on the upper branches of the tree, in axils of scale leaves either singly or in groups of 2-4.  Female cones are seen in February and get pollinated within 3-4 months  Complete maturation and seed dispersal takes place in the 3rd year of development  Each cone consists of central axis bearing spirally arranged ovuliferous scales (60-70)  On young cones a small thin & leathery bract scale can be below the ovuliferous scale  Each ovuliferous scale has two ovules on its upper surface  Cone on maturity is usually cylindrical and 15-20cms in length
• 62.
  Female Cone
• 63.
  Megasporophyll The ovuliferous scaleis thick, large, woody & brownish structure More or less triangular in outline – broad, terminal portion is apophysis with its centrally projected area – the umbo Basal portion is narrow and bears two naked, sessile anatropous ovules on its upper surface
• 64.
  Ovule Structure  Micropyleof the ovule faces the central axis of the cone  The single integument is fused to the nucleus except for a short distance near the micropyle  Embedded in the nucellus ,the archesporial cell divides meiotically to form four megaspores
• 65.
  Male Gametophyte  Earlydevelopment takes place inside the microsporangium  Pollen grains are released at the 4- celled stage (2 prothalial, a generative cell and tube cell )  Pollination is anemophilous and pollen reach the pollen chamber of the ovule through micropyle  Further development here, results in the formation of pollen tube which carries the two unequal male gametes to the neck of the archegonium  The released male gametes will fertilize the egg cell resulting in zygote formation  Time gap of 12-14 months is seen between pollination and fertilization
• 66.
  Female Gametophyte The innermost functional megaspore further gives rise to the haploid female gametophyte tissue wherein the archegonia develop. The venter of the archegonia contains the upper ventral canal cell and the larger egg cell.
• 68.
  Young Sporophyte Embryo developmentis meroblastic In early stages the embryonal tier of the pre- embryo splits apart forming 4 apical segments each with its suspensor Each of these terminal embryonal cell give rise to a mature embryo , thus Cleavage polyembryony is observed
• 71.
  Gymnosperms-general charaters Gymnosperms aresimple and primitive seed-bearing plants without flowers. The plant body is sporophytic and is differentiated into root,stem and leaves. All gymnosperms are usually wind-pollinated. Leaves have thick cuticle and sunken stomata. Gymnosperms are heterosporous.magasporangia and microsporangia occur on mega and microsporophylls respectively.
• 72.
  Economic importance of gymnosperms sedfor making egetables. ith of As food Seeds of some species are edible: Cycas, Ginko, Pinus, Gnetum The seeds and stems of cycas yield ‘sago’ which is a starch and is also called “arrow root”. Zamia is a rich source of starch. Seeds and stem of Cycas revoluta u wine. young leaves of Cycas cooked as v kaffir bread’ prepared from the stem p Encephalartos.
• 73.
  Cycas Cycas seeds
• 74.
  Ginko Ginko seeds
• 75.
  Pinus Pinus seeds
• 76.
  Gnetum Gnetum seeds
• 78.
  As medicine Ephedrine(alkaloid) extractedfrom Ephedra used in treating asthma, cough, cold, bronchitis etc. Tincture of Ephedra is a cardiac stimulant. Anti cancerous drug called taxol, is obtained from the bark of Taxus. The juice is extracted from young leaves of Cycas revoluta is used for curing blood vomiting and flatulence. In Assam the pounded stem of Cycas pectinata is used as a hair wash for diseased hair roots.
• 79.
  Ephreda
• 80.
  As ornaments Species ofCycas are used for decoration purposes. Ginkgo bioloba possess beautiful ornamental leaves. Thuja, Pinus, Taxus etc are grown in parks.
• 81.
  T axus
• 82.
  In industry 1.Gum- Cycasgum used as a adhesive, antidote for snake bites and using malignant ulcers. 2.Tannins- Tannins are used in leather industry and it is extracted from the bark of Araucaria, Sequoia etc. 3.Canada balsam- it is turpentine obtained from Abies balsamea and used as a mounting medium in biological preparations. 4.Amber- it is a fossil resin obtained from Pinus succinifera. Wood of pinus is used for doors, poles, beams, railway wagon flooring etc. 5.Plywood is prepared from Podocarpus. 6.Papers like newsprints, writing and printing
• 83.
  Tannins are preparedfrom the bark of Araucaria and Sequoia
• 86.
  Porocarpus
• 87.
  7.The leaves ofCycads are used for preparing baskets, mats, hats, brooms etc. 8.The fibers obtained from the leaves of Cycas and Macrozamia are used for stuffing pillows and making mattresses. Source of oils *Oil extracted from seeds of C.revoluta, Macrozamia, Pinus cembra and Cephalotaxus drupacea are used as edible oils. *Red cedar wood oil extracted from the heart wood of Juniperus virgiana is used for cleaning microscopic preparations and for oil immersion lenses. *Oils obtained from Cedrus deodara, Ciyptomeria japonica and Cupressusserm perivirens are used in preparations of perfumes.
• 88.
  Thank you
• 90.
  1. Coniferophyta Conifers includePines, Firs, Spruces,Yews, Junipers, Cedars, Cypress, and Redwoods
• 91.
  1. Coniferophyta The termconifer comes from the reproductive structure, the cone, which is a cluster of scalelikesporophylls About 550species
• 92.
  1. Coniferophyta Many conifersareevergreen
• 93.
  1. Coniferophyta They havelong, thin, needle-shaped leaves (Cypress)
• 94.
  1. Coniferophyta Some plantshave broad and flat leaves
• 95.
  1. Coniferophyta Well adaptedin drier climates
• 97.
  2. Cycadophyta • Seedplants made up of only three living families • Members are scattered around the globe but are restricted to tropical or subtropical climates • The cycads radiated and spread widely in the early Mesozoic • Dioecius
• 99.
  3. Ginkgophyta Ginkgos producebad smelling fruites Used as medicinal plants