Gymnosperms.pptx

Prepared by Dr Thirunahari Ugandhar

1. GYMNOSPERMS MORPHOLOGY, ANATOMY AND REPRODUCTIVE STRUCTURE

2. INTRODUCTION The Gymnosperms are 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 ఉత్పత్తి చేసే మొక్కల సమూహం, ఇవి కోనిఫెర్లు, సైకాడ్లు, జింగో, మరియు గెనెట్ఫైట్లను కలిగి ఉంటాయి. పదం "జిమ్నోస్పెర్మ్" పదం జిమ్నోస్పెర్మోస్ నుండి వచ్చింది, దీని అర్ధం "నగ్న విత్తనాలు", వారి గింజల యొక్క ఎడతెగని స్థితిలో (వారి పరాధీన స్థితిలో ovules అని పిలుస్తారు) తరువాత. జిమ్నోస్పెర్మ్ విత్తనాలు కొలత యొక్క ఉపరితలంపై సాధారణంగా అభివృద్ధి చెందుతాయి- లేదా శంఖుల వంటి ఆకు 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 మనుగడలో * లేదా జిమ్నోస్పెర్మ్స్ యొక్క ప్రస్తుత జాతులు ఉన్నాయి. జిమ్నోస్పెర్మ్లు చివరి కార్బొనిఫెరస్ కాలం నుంచి పుట్టుకొచ్చాయని విస్తృతంగా అంగీకరించారు. 380 మిలియన్ సంవత్సరాల క్రితం సుమారు చివరి దేవొనియన్ కాలపు శిలాజ ప్రోజిమ్నోస్పెర్మ్లలో విత్తన మొక్కల ప్రారంభ లక్షణాలు స్పష్టంగా కనిపిస్తున్నాయి. * ఉనికిలో ఉన్న జీవనశైలిని సూచిస్తున్న జీవజాతిలో (సాధారణంగా జాతులు, జాతి లేదా కుటుంబాలు) సూచించడానికి సాధారణంగా ఉపయోగించే పదం. ఈ పదాన్ని మనుగడలో వ్యత్యాసం కలిగి ఉంది

4. 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.

5. 60-70 జాతి మరియు 600-630 జాతులు (696 ఆమోదించబడిన పేర్లు) మొత్తం ఆరు నుండి ఎనిమిది కుటుంబాలు కలిగిన జిమ్నోస్పెర్మ్లు చాలా ఎక్కువగా ఉన్నాయి. కోనిఫర్లు అడవులు మరియు చాలా సతతహరితాలతో ఉంటాయి. అనేక కోనిఫెర్ల ఆకుల పొడవాటి, సన్నని మరియు సూది వంటిది ఒక మైనపు పూతతో, చాలామంది కాప్రెస్సీయే మరియు కొన్ని పోడోకార్పెసీతో సహా ఇతర జాతులు ఫ్లాట్, త్రిభుజాకార-స్థాయి ఆకులు కలిగి ఉంటాయి. 130 రకాల జాతులు కలిగిన జిమ్నోస్పెర్మ్ యొక్క తదుపరి అత్యంత విస్తారమైన బృందం సైకాడ్లు. ఇతర మనుగడలో ఉన్న గ్రూపులు 75 - 80 జాతి జీటాలేల్స్ మరియు జింగో యొక్క ఒక జాతి .

6. 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 . ప్రామాణిక లక్షణం లేదా జిమ్నోస్పెర్మ్లను గుర్తించడానికి సహాయపడే లక్షణాల సమితి ఉనికిలో ఉంది. జిమ్నోస్పెర్మ్ యొక్క విచిత్ర లక్షణాలు కొన్ని ఇక్కడ ఉన్నాయి జిమ్నోస్పెర్మ్లు వారి విత్తనాల చుట్టూ బయటి-కవరింగ్ లేదా షెల్ లేదు. జిమ్నోస్పెర్మ్లు హేటెరోస్పోరోస్, అంటే అవి వివిధ మగ మరియు ఆడ స్పోర్ట్స్లను ఉత్పత్తి చేస్తాయి. మైక్రోస్పొరలు పుప్పొడి గింజలుగా అభివృద్ధి చెందుతాయి మరియు మెగాస్పోర్స్ ఒక అండాకారంలో ఉంటాయి.

7. 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: Long shoots or branches of unlimited growth. Dwarf shoots or branches of limited growth

8. Sporophyte : The asexual and 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.

9. CYCADALES: CYCAS The members 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.

10. 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 and India. 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. r evolu t a a n d C. s i a m e n sis are wid e ly grown in gardens .

11. 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.

12. 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.

13. 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.

14. SPOROPH Y TE Plants are low and palm-like , height 4-8 feet. Tallest species, C. media – up to 20 feet high Stem u n b r an c h e d , columnar and c o ver e d with pers i s t ent leaf bases. Leaf segment remains circinnately involute within the bud– leaves dimorphic. Fema l e repr o duc t ive s t ructure s – the m eg a spo r ophyl l s are not aggregated in cones. Ov u les ( 2 o r m ore) b o r ne o n the low e r m a r gi n s in ascending order

15. External Morphology Stem- Cycas plant 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.

16. External Morphology The pinnately compound megaphyllous leaves have 80-100 pairs of leaflets arranged on the rachis Leaf base i s r h ombo i dal i n sha p e a nd attaches the leaf transversely to the stem The leaflets are thick , leathery in texture, ovate or lanceolate in shape & photosynthetic in function.

17. External Morphology Scale leaves 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 So m e of the later a l r o ots g r o w a pogeot r opi c a l ly to w ar d s the surface of soil and branch dichotomously These roots are short , thick and swollen at the tips.

18. External Morphology The much 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 inf e s t ed b y N2 (cyanobacteria); bacteria f i x e d b l ue - gre e n & diatomse a l g a e e g . Nostocpunctiforme, Anabaenacycadacaerum Symbiotic relationship thus established

19. Anatomy Root Young root shows typical structure like that of a dicotyledonous root Outer most layer , epiblema , encloses the paren c h y m atous cort e x in t erspersed with tannin cells and mucilage canals Endodermis with casparian thickenings Per i cycle is m ul t ila y er e d wi t h th i n c e ll shaving starch grains Vascular tissue within is typically radial Roots usual l y di a rch t o t e tra a rch , rarely polyarch Vessels absent in vascular tissue Pith reduced or absent

20. Anatomy –Root Older roots 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

21. Anatomy –Root Coralloid Roots Has additional a lgal zone in the cortex Cells of algal zone palisade like and form the middle cortex

22. Anatomy –Stem Stem Show irregular 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 vascu l a r tissue Narrow zone of having open, end a rch vascul a r bundles arranged in a ring and separated from each other by wide medullary rays Pith is large, parenchymatous shaving mucilage canals and starch grains

23. Anatomy –Stem and wide Old stem of Cycas shows secondary growth W ood m ano x ylic ty p e with sc a n ty x y l e m medullary rays

24. Anatomy –Rachis Rachis of Cycas 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.

25. 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

26. T.S of Cycas Leaflets

27. Reproduction –Vegetative V e geta t ive repr o duc t ion is by means of bulbils Develop in crevices of scale leaves and leaf bases at the basal part of an old stem Pr o d u c es new plant on detachment

28. Reproduction –Sexual Strictly dioecious 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 Us u ally p r e s e nt in sori– each w ith 2- 6 sporangia They contain a large nu m b er of haploid microspores (pollen grains) S T ROBI L US

29. Female Reproductive Structures Female plant do not produce definite cones A whorl of spirally arranged megasporophylls arise around the short apex Each megasporophyll resembles the foliage leaf and approximately 10-23 cms. long Lower petiolar part bears the naked ovules on the margins

30. Ovule Structure La r ge s t o v ule (6 cm s . 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 .

31. Megasporangium The megaspore develops in 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 c e l l i n t he venter undergoes fertilization o f ar c hegonia , by the moti l e spermatozoid forming diploid zygote .

32. Pollination -Development of male gametophyte after pollination The pol l en gra i ns are carri e d by wind ( A nemop h i l y) a nd c au g ht b y pol l inat i on 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.

33. During the germination 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

34. Young Sporophyte–Embryo Embryo development is meroblastic. Pro embryo shows upper haustorial part, middle elongating suspensors and the basal meristematic embryonal region.

35. LIFE CYCLE OF GYMNOSPERMS

36. CONIFEROPHYTA: PINUS This is 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.

37. 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.

38. 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 . 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 .

39. 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. 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.

40. 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 .

41. Sporophytic Plant Body Adult plants are tall trees up to 200 feet in height Perennial, xerophytic plants appearing pyramidal or conical due to radial branching Branches are d i m orph i c – long sh o ots and dwarf shoots (spurs) Leaves a re dimo r phic – S c a le lea v es and g re e n acicular leaves Male and fem a le c ones present on the same p lant, hence monoecious

42. 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

43. Branches of unlimited growth are the long shoots Arranged spirally around the main trunk Bea r scale leaves a n d dwarf s h o ots in axils o f scale leaves Br a nches of li m ited g r owth or dwarf sh o ot la c ks apical bud P o s s e s s 8 - 1 sp i rally arran g ed s c ale lea v es terminating into 1-5 needle like foliage leaves at apex

44. 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)

45. External Morphology – Root Plant possesses tap root Elongated structure with strong lateral branches Ro o t-hairs scanty; function taken u p b y e c t o trophic mycorrhiza (fungus roots) It is s y m b i o t ic ass o ciati o n o f f u n gal m y c elium o n t he root’s surface Helps in abs o rption o f n u tr i ents & p r o t e c tion f r o m pathogens Fungal species identified are Rhizopogon, Amanita, Boletus, Entoloma, etc. – mostly members of Basidiomycetes

46. Anatomy – Root Rese m bles ty p ical d icot y ledono u s root. Pili ferous epiblema bear unicellular root hair (seen only in young roots) p a renchy m atous co r tex and per ic ycle layers Broad follows Endoder m is seen next V ascu l a r ti s sue i s ra d ia l ly arranged in 2-6 groups of xylem and phloem This t i ss u e lacks true vess e ls a n d companion cells Resin canals present in xylem patch making it Y-shaped Old roots show secondary growth

47. Anatomy – Stem Typically dicotyledonous stem Cuticularized epidermis encloses the li gn i f i e d s c lerec h y m at o u s hypodermal layer below Inner cortex is thin walled parenchyma containing chloroplasts and resin canals Vascular bundles are conjoint, collateral, endarch , open and form a ring Medullary rays are narrow Vessels in xylem and companion cells in phloem are absent

48. Secondary growth in stem 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

49. 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

50. Mesophyll not differentiated further These c e lls have pe g -li k e i n f o l d i n g s o f c e ll u lo s e 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

51. REPRODUCTION T a k es pl a ce b y mea n s of sp o res – microspores (male) and ( fem a l e ) . The pl a nts are meg a spores t h er e fo r e heterosporous The ma l e and female c o n es oc c ur on the same p la n t, but di f f e r e nt bra n ch e s i.e. monoecious

52. Male cones (Staminate cones) 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.

53. Male cones (Staminate cones ) Each c one has 60 - 100 spirally ar r a nged microsporophylls Two microsporangia are p r es e nt o n t he underside of each microsporophyll Development of microsporangium is eusporangiate type Within the microsporangium, the microspore mother cells undergo meiotic divisions to form haploid microspores

54. 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”

55. Female cone (Ovulate cone) 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 Ea c h cone cons i s ts of ce n tral a x is be a r i ng s p ira l ly arra n ged ovuliferous scales (60-70) O n young cones a s m all th i n & le a thery bract s c a le c an 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

56. Female Cone

57. Megasporophyll The ovuliferous scale is 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

58. Ovule Structure Micropyle of 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

59. Male Gametophyte Early development 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

60. Female Gametophyte The inner most 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.

61. Young Sporophyte Embryo development is 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

62. Gymnosperms-general charaters Gymnosperms are simple 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.

63. Economic importance of gymnosperms sed for making e g etable s . 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 .

64. Cycas Cycas seeds

65. Ginko Ginko seeds

66. P i nus Pinus seeds

67. Gnetum Gnetum seeds

68. As medicine Ephedrine( alkaloid) extracted from 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.

69. E p hreda

70. As ornaments Species of Cycas are used for decoration purposes. Ginkgo bioloba possess beautiful ornamental leaves.  Thuja, Pinus, Taxus etc are grown in parks.

71. T a x us

72.  In industry Gum - Cycas gum used as a adhesive, antidote for snake bites and using malignant ulcers. Tannin s- Tannins are used in leather industry and it is extracted from the bark of Araucaria, Sequoia etc. Canada balsam - it is turpentine obtained from Abies balsamea and used as a mounting medium in biological preparations. Amber - it is a fossil resin obtained from Pinus succinifera . Wood of pinus is used for doors, poles, beams, railway wagon flooring etc. Plywood is prepared from Podocarpus . 6.Papers like newsprints, writing and printing papers are being prepared from the wood pulp of

73. Tannins are prepared from the bark of Araucaria and S e qu o ia

74. Porocarpus

75. The leaves of Cycads are used for preparing baskets, mats, hats, brooms etc. 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.

76. Than k you

77. 1. Coniferophyta  Conifers include Pines, Firs, Spruces, Yews, Junipers, Cedars, Cypress, and Redwoods

78. 1. Coniferophyta  The term conifer comes from the reproductive structure, the cone, which is a cluster of scalelike sporophylls  About 550 species

79. 1. Coniferophyta  Many conifers are evergreen

80. 1. Coniferophyta  They have long, thin, needle-shaped leaves (Cypress)

81. 1. Coniferophyta  Some plants have broad and flat leaves

82. 1. Coniferophyta  Well adapted in drier climates

83. 2. Cycadophyta Seed plants 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

84. 3 . Ginkgophyta G i nkgos pr o duc e ba d s m ell i ng fru i tes Used as medicinal plants

85. 4. Gnetophyta They are closely related with conifers This likeness leads scientists to believe that gnetales are evolved from conifers This theory is supported by extensive fossil records, some dating back to the Palezoic era  Though they are non-flowering plants, gnetales have a reproductive structure similiar to that of flowering plants

86. Habitat of Gymnosperms Occupy large areas of the Earth's surface Can grow in drier conditions Gnetophytes grow at high altitudes  Cycads are distributed throughout the world but are concentrated in equatorial regions

87. Habitat of Gymnosperms. Cont… Gymnosperms that occupy areas of the world with severe climatic conditions are adapted to conserving water; leaves are covered with a heavy, waxy cuticle and pores (stomata) are sunken below the leaf surface to decrease the rate of evaporation

88. Lifecycle The gymnosperm (pine tree) life cycle takes about two years to complete Exhibits alternation of generation The dominant photosynthetic part of the life cycle is the sporophyte Sporophyte is diploid (2n) Gametophyte (n) is dependent on sporophyte Cones are reproductive structures(Gametophytes) Pollen grains are produced by male cones and carried to female cone by wind where fertilization occurs After fertilization, a sporophyte is formed which is enclosed in a seed. It germinates to produce a sporophytic plant once again

89. Ecological Importance Provide food and habitat for wild life Forests prevent soil erosion Reduce green house gases Conifers are often featured in gardens Junipers are low-growing shrubs and are cultivated to cover grounds Conifers are affective wind breakers

90. Economical Importance T h e y ar e ma j or sou r c e of lu m ber , pape r p u l p , turpentine and resins They are used as fuel  They are major source of world’s timber  Used as medicines (Ginkgos) are widely u s ed as  Source of food (Pine Nuts)  G y mno s per mo u s plants ornamentals

91. Classification of GYMNOSPERM

92. Classification Gymnosperms include a number of fossil and living forms. They include the primitive members of the Spermophyta (seed- bearing plants) and form a link between the Pteridophyta on the one hand and the angiosperms on the other. Various attempts have been made by different workers to classify the Gymnosperms. One of the earliest attempts was made by Bentham and Hooker (1866-1883), when they divided seed bearing plants into Dicots, Gymnosperms and Monocots. Gymnosperms were further divided into Cycadaceae, Gnetaceae and Coniferae. Engler (1885) divided Gymnosperms into seven groups as follows: 1. Cycadofilicales 2. Cycadales 3. Bennittitales 4. Cordaitales 5. Ginkgoales 6. Coniferales 7. Gnetales

93. Coulter and Chamberlain (1917 ) adapted Engler’s system with slight modifications and divided gymnosperms into seven orders: Cycadofilicales, Cycadales, Bennittitales, Cordaitales, Coniferales, Ginkgoales and Gnetales. He further divided order Coniferales into two families (Pinaceae and Taxaceae) and six sub-families as follows: Families Sub-families Orders Cycadofilicales Cycadales Bennittitales Cordaitales Coniferales • Pinaceae Abietineae, Taxodineae, Cupressineae , Araucarineae • Taxaceae Taxineae, Podocarpineae Ginkgoales Gnetales

94. Depending upon the composition of wood, Seward (1919) divided gymnosperms into two classes: i) Manoxylic with loose textured and porous wood, and ii) Pycnoxylic with compact wood. Orders Cycadales, Cycadeoidales and Cycadofilicales were included in the former whereas, the latter included the orders Cordaitales, Ginkgoales, Coniferales and Gnetales. Prof. Birbal Sahni (1920) classified gymnosperms into two divisions depending upon the axial or foliar origin of the ovules. These are: i) Stachyspermae – in which the ovules arise on the axial organs, and ii) Phyllospermae – in which the ovules are borne on leaves. Stachyspermae was further divided into four orders and Phyllospermae into three orders as follows:

95. • Divisions Orders • Stachyspermae Cordaitales, Coniferales • Ginkgoales, Gnetales Gymnosperms Phyllospermae Cycadofilicales, Bennittitales • Cycadales Chamberlain (1934) however, divided the gymnosperms into two large groups A. Cycadophyta and B. Coniferophyta. In the Cycadophyta, sporophylls are in cones. They include three orders: Cycadofilicales (Pteridospermae)-extinct Bennettitales (Cycadeoideales)-extinct Cycadales-Mesozoic to present day. The Coniferophyta is divided into four orders: Ginkgoales-Palaeozoic to present day. Cordaitales-extinct Coniferales-Palaeozoic to present day Gnetales-Recent.

96. Raizada and Sahni (1938) have summarized the classification of gymnosperms as follows: Cycadophytes: Pteridospermae (Cycadofilicales)-Carboniferous. Extinct. Cycadeoideales (Bennettitales)-Mesozoic. Extinct. Cycadales-Mesozoic to present day. Pentoxylales: Jurassic Coniferophytes: Cordaitales-Palaeozoic. Exinct Ginkgoales-Palaeozoic to present day. Coniferales-Palaeozoic-Mesozoic to present day Gnetales-Recent.

97. Chamberlain (1935) classified gymnosperms into: • • Gymnosperms with profusely branched trunks, leaves simple (needle-like, scale-like or laminate), stems with small pith and cortex. Secondary xylem cylinder massive and less parenchymatous (pycnoxylic wood). The group includes extinct as well as extant orders like Gymnosperms with fern-like pinnatifid leaves, weakly branched large globose or columnar trunks, having large conspicuously developed pith and cortical zones in stem. Secondary xylem cylinder small, composed mainly of tracheids and abundant parenchyma (manoxylic wood). Group well represented in fossil record. The only surviving representatives are the modern cycads. Orders 1. Cycadofilicales 2. Bennettitales 3. Cycadales Orders: 1. Cordaitales 2. Voltziales 3. Coniferales 4. Ginkgoales 5. Gnetales Coniferophytes Cycadophytes Gymnosperms

98. In 1957 prof. D.D PANT gave the modification of Arnold`s classification and gave the following system.. Cycadophyta Chlamydospermophyta Conifrophyta CLASS-1- Pteridosp e r m o p s ida Orders- Lygniopteridales Medullosales Glossopteridales Peltaspermales Corystospermales Caytoniales CLASS-2- C y cadopsida Orders- Cycadales CLASS-3- Penta x y lopsida Orders- Pentoxylales CLASS-4- Bennet t i t op s i d a Orders- Bennettitales CLASS-1- Gnetop s i d a ORDERS- Gnetales W el w itschi a les CLASS-1- C oniferop s ida Orders- Corditales Coniferales Ginkgoales CLASS-2- Ephedrop s ida Orders- Ephedrales CLASS-3- C zekano w skiales Orders- C zekano w skiales CLASS-4- T a x opsida Orders- Taxales

99. Kramer & Green (see Kubitzki, 1990) have classified the Division Gymnosperms into two Subdivision as follows:- • Cycadophytina Coniferophytina Classes- Cycadatae Order- Cycadales Families - 1. S tangeriaceae 2.Boweniaceae 3.Cycadaceae 4.Zamiaceae Classes - G n etatae Orders- Gnetales Families- 1. E phe d rac eae 2.Gnetacea e 3. W el w itsc hiaceae Classes- Gin k goatae Order- Ginkgoales Families - 1.Ginkgoa c e ae Cla s s es - Pinatae Order- Pinales (Coniferales) Families- 1. Taxaceae 2.Cep h alota x a c eae 3.Phyllocladaceae Podocarpaceae A rau c aria c e a e 6. Sciadopityaceae 7. Taxodiaceae 8.Cup r e s sa c eae 9. Pinaceae

100. Flow charts showing classification by different workers:-

101. The modern gymnosperms are commonly grouped under four orders: 1. Cycadales; 2. Ginkgoales; 3. Coniferales and 4. Gnetales The Cycadales and the Ginkgoales include living members which have a long, fossil history and can be regarded as ‘living fossils’. Ginkgoales in the past (early Mesozoic) were represented by widely distributed group of plants, but now the order is represented by a single species Ginkgo biloba. The Coniferales from the most conspicuous order of the living gymnosperms and include the plants like Pinus, Cedrus, Abies, Juniperus, Cupressus, Biota, etc. The Gnetales are represented by three living genera, e.g., Gnetum, Ephedra and Welwitschia.

102. Living Gymnosperms Cycads Gnetophytes G i n kgoes Conifers

103. •

104. The trees are branched,woody and perennial. The leaves are dimorphic scaly and foliar. Tap root system mostly associated with fungi [mycorrhizal association] Reproductive structures are formed on leaves which arrange to form cones male and female cones are formed sepratly. Pollen grains are wind spread and embryo formed is di to polycotylednous

105. The Largest and the Oldest Plants are both Conifers Bristlecone pines of the California White Mountains are the oldest Giant Sequoias of the California Sierras are the largest

106. Earth" - General Sherman - 2200 years old , 275 feet tall , 30 feet in diameter at the base . 119.3 miles of 1X12 planks Sequoia National Forest, CA

107. There are seven living families of Conifers Norfolk Island Pines Junipers and Cedars Yew Sequoias and Redwoods Pines, Fir Spruce Five of the most familiar

108. The division coniferophyta contain following 7-families. PINACEAE It is composed of 10 genera Cedrus , Pinus , Cathaya, Tsuga,Abies etc. Tall and well branched trees. Posses dwarf and long shoot dwarf shoot posses scaly and needle like foliar leaves.

109. Taxodiaceae Comparises evergreen or deciduous trees and plant parts are mostly spirally arranged. Both male and female cones are arranged on same plants. Contain ovuliferous scales with 2 to 9 ovules on each. Pollen grains are wingless and lack prothalial cells. Seeds may be winged or wingless or irregular in shape. Consist of…. Taxodium , Sequoia , Sequoiadendron , Taiwania , Cunninghamia etc.

110. Cupressaceae The family comparises evergreen much branched trees or shrubs . The plant parts are arranged opposite decussate or in whorls of 3 or 4. Juvenile leaves may be linear adenate or adpressed completely hiding the stem. Leaves may be glandular and grooved. Male and female cones occur on same plant. There are nearly 22 genera some are.. Tetraclinis , Juniperus , Callitris , Thuja etc

111. T H U JA

112. Podocarpaceae Leaves are extreamly variable. True leaves are small,scale like and are replaced by phylloclades. Phylloclades are flattened much branched with fiabelliform. Male and female cones are seprate solitary axile or terminal. It consist of 7 genera some are .. Podocarpus, Dacrydium,etc

113. Podocarpus macrophyllus

114. Araucaria c eae Evergreen and highly resinous trees. Leaves are small,stiff,awl-like or large and leatherhy. Plant may be monoecious or dioecious. Pollen grain are wingless with multiple persistant prothalial cells. It consist of 2 genera … Araucaria , Agathis .

115. Cephalotaxaceae Cephalotaxaceae is a monogenic family with only one genera Cephalotaxus. Named such due to shape of male cone from the greek word “kephale” means head. Male cones are present in globose heads. Shrubs or small yew like dioecious plants. Male trees posses unbranched shoot. Leaves are more or less same size ,falcate,subacute,base round,and whitish beneath.

116. Taxaceae These are much branched evergreen woody shrub or small,rarely large trees. The leaves are simple,linear and small and sre spirally arranged. The wood is pycnoxylic. Plant is dioecious with male strobilus consist of a cone axis. The family is represented by 5 living genera…. Amentotaxus, Torreya,Taxus,Psedotaxus,Austrotaxus.

117. 2 Cycado p hyta

118. CYCADOPHYTA Rarely branched trunks with soft pithy wood. Plants are dioceous in nature with compound leaves. Microsporangia (Male gametophyte) grows within the ovule. Male gametes are multicilliated and motile. Motile sperm released after several months, sometimes after the seed has fallen.

119. Cycads Appeared on Earth 250 MYA Reached their greatest abundance and diversity during the Jurassic Declined sharply during the Cretaceous radiation of the angiosperms.

120. Cycad Stems Columnar Little branching Not very woody

121. Certain roots in Cycads grow toward the soil surface Corr a lo i d Roots

122. A Closer Look at Coralloid Roots Grow upward near soil surface Branch to form masses Root cortex inhabited by Cyanobacteria (carry out nitrogen fixation)

123. Cycads produce pollen and seeds in cones Cones develop at apex of stem

124. All Cycads are Dioecious Individual plants produce either pollen cones or seed cones Cycas revoluta Pollen Cone Seed Cone

125. Ginkgophytes – Ginkgo Extensive fossil record but…only 1 living species: Ginkgo biloba ! Highly branched tree withwell developed wood. Deciduous, fan-shaped leaves with dichotomous venation. Dioecious : male and female trees -male: “cone” with lateral stalks bearing microsporangia -female: no cone, axis with 2 ovules (outer integument layer fleshy) motile sperm (ancestral

126. Ginkgo – Vegetative Characteristics

127. Ginkgo is Deciduous

128. Ginkgo Stems Extensive branching Very woody

129. Ginkgo Stems long shoot spur shoot

130. All Ginkgo trees are Dioecious Individual plants produce either pollen “cones” or seed “cones” Produced on spur shoots C

131. Ginkgo produces a seed with a fleshy seed coat Seed Coat contains Butyric Acid Seed Coat is not edible

132. Ephedra is a desert shrub

133. Gnetum is a tropical vine or small tree

134. Welwitschia is a bizarre plant of an extremely arid environment

135. Welwitschia produces only two adult leaves Welwitschia forms a short stem and deep tap root

136. Thank Y ou