Gymnosperms

Gymnosperm is from the Greek “gymnos” naked, and “sperma” seeds. They are groups of vascular plants that reproduce by means of an exposed seeds or ovules. They are phanerogams according to A. W. Eichler.

1. Done by: TheRock Peterson

2. Gymnosperms Group 9

3. Presentation Outline Overview of Gymnosperms E volution Characteristics of Gymnosperms Comparing the sporophyte-gametophyte relationship in seedless plants and Gymnosperms Life cycle of a pine The four phyla of Gymnosperms and their Importance

4. Overview o f Gymnosperms Gymnosperm is f rom the G reek “gymnos” naked , and “sperma” seeds Gymnosperms are groups of vascular plants that reproduce by means of an exposed seeds or ovules They are phanerogams according to E ichler They include 83 genera , 12 families and 1,080 living species

5. Overview Cont’d… They include four phyla; Coniferophyta (Conifers) Pine, Spruce, redwood… Cycadophyta (Cycads) Fig 1.1 Cycad Conifer

6. Overview Cont’d… Ginkgophyt a( ginkos ) Ginkgo biloba Gnetophyta/ G netopsida Ephedra Ginkgo biloba Witwhicher

7. Characteristics of Gymnosperm Most gymnosperms are evergreen with a small percentage that tends to be deciduous Most are trees (woody stem) Eg : redwood A few are shrubs Seeds are not borne on flower or in fruit as angiosperms They are paraphyletic taxonomically They have a root system similar to a dicot stem

8. Characteristics Cont’d… Also called spermatophytes Most possess needle- like leaves Have vascular tissues Tracheids (are present in all) and vessel elements (present only in gnetophytes)

9. Needle-like leaves of Some Gymnosperms

10. Characteristics Cont’d... They have cone as their reproductive structure (strobili-strobilus) Two types of cones: pollen cone (pollen) and ovulate cones (eggs) They form spores: micro-megaspores are produced by sporophyte generation These gymnosperms include the tallest and oldest trees Ovulate cone Pollen cone

11. Characteristics Cont’d...

12. Representation of Gymnosperms

13. General Characteristics: Habitat Gymnosperms occupy a large area of the earth surface Some are xerophytic Some live in equatorial regions Concentrated in forests and woods They can also grow a t high altitudes Lithophytes Psammophytes

14. Selective Advantages of Seeds In Seed Plants Seeds include food for developing embryo and germinating seedling They provide nourishment for the embryo during dormant state Attract seed eating animals which destroys some seeds, but distribute others Seed coat serves as a barrier against bacterial and fungal decay

15. Evolution of Gymnosperms Gymnosperms are believed to have evolved from the paleozoic to the mesozoic eras There are 3 groups of extinct plants that played important roles in the evolution of modern gymnosperms They are progymnosperms , aneurophytales , and a groups of primitive gymnosperms: archaeopteridales In middle devonian period, progymnosperms arose from the trimerophytes which were extant until the lower carboniferous period

16. Evolution Cont’d… Progymnosperms gave rise to aneurophytales that gave rise to pteridosperms and archaepteridales Aneurophytales were homosporous , producing many identical spores and had three dimensional branching Unlike the progymnosperms , the pteridosperms produced seeds appearing in the late devonian period

17. Evolution Cont’d… Pteridosperms were the first seed plants, with integuments protecting ovules to various degrees Another extinct group of Pteridosperms are the Bennettitales , which resemble present cycads. The Archaeopteridales may have given rise to the Cordaitales and the Voltziales The Archaeopteridales arose from the Aneurophytales

18. Evolution Cont’d... The cordaitales were trees and shrubs during the carboniferous and permian periods both in swamp and dry land which had slender leaves. They also had vascular cambium tissues and ovulate cones. The cordaitales apparently gave rise to the phylum ginkgophyta , which persists to present day and others which have relatives to cycadophyta , gnetophyta and coniferophyta . Voltziales is an extinct order of trees that gave rise species related to modern conifers.

19. Mode of Nutrition Gymnosperms are photosynthetic S ymbiotic

20. Distinguishing Features between Angiosperm and Gymnosperm Pollination Angiosperms rely on wind and animals Gymnosperms rely on wind Time interval between pollination and fertilization In A ngiosperms it occurs simultaneously G ymnosperms pollen sits within the cone for up to 15 plus months before fertilization

21. Distinguishing Features between Angiosperm and Gymnosperm Double fertilization In A ngiosperm one sperm fertilizes egg, the other combines to form an endosperm D ouble fertilization in Gymnosperms is absent Fruits A ngiosperms produce fruit, animals are used as agents of pollination Gymnosperms form seeds without fruits

22. Comparing The Sporophyte-gametophyte Relationship In Seedless Plants and Gymnosperms Seedless plants Sporophyte depends on the gametophyte throughout its life. Exosporic development Homosporous , with one type of spore produced by one type of sporangium. Gymnosperms Seed can germinate and grow into an independent sporophyte. Endosporic development Heterosporous ; producing two types of spores: microspore and megaspore. NOTE: Heterospory occurs in some living species of seedless vascular Plants, genus selaginella and a few ferns .

23. Comparing the sporophyte-gametophyte relationship in seedless plants and Gymnosperms

24. Reproduction In Gymnosperms Gymnosperms were the most dominant phylum is the mesozoic era. The life cycle in gymnosperms involves an alternation of generation. Dominant sporophyte in which the female gametophyte and reduced gametophytes resides. The male and female reproductive organs can be formed in cones or strobili The male and female sporangia are produces either in the same plant or on separate plants`

25. Reproduction Cont’d… Sporangia are either monoecious or dioecious Diploid sporophyte stage in most of their life time (cycle), with a haploid gametophyte that is short lived Two spore types: microspores and megaspores are typically produced in the pollen cone or ovulate cone respectively. There are two main modes of fertilization found in gymnosperms Male gametophyte and female gametophyte

26. Pine Life Cycle

27. Classification of Gymnosperm There are four surviving phyla of gymnosperm They vary greatly in appearance and habitat They are grouped into: Conifers , Cycads , Ginkos and Gnetophytes The four phyla of living gymnosperms are of separate clades or lineages, unlike the angiosperms, which are a monophyletic, single lineage

28. PHYLUM CONIFEROPHYTA

29. Phylum Coniferophyta The Coniferophyta division contains conifers which has the greatest variety of species among gymnosperms Most conifers are evergreen (they retain their leaves throughout the year ) They include some of the largest, tallest and oldest trees on the planet Examples of conifers include The familiar pines, firs, spruces, yews, hemlocks, and junipers The word conifer means ‘cone-bearer’, it is a distinct characteristics common to conifers.

30. Coniferophyta Cont’d... They have needle-like leaves needle leaf conifers also have a waxy coat on the leaf surface to help prevent water loss in the dry climate this taxon includes secondary growth and the production of protective buds They also have a significant amount of intermodal elongation which allows them to grow faster than many other plants. Consists of 50 genera and 550 species

31. Coniferophyta Cont’d... Not all of the conifers resemble the needle‐leaved pines in appearance or length of time to complete the sexual reproductive cycle Some conifers are deciduous, such as larch ( Larix ), bald cypress ( Taxodium ), and the dawn redwood ( Metasequoia ) They have vascular tissues. Meristems and other plant tissues Cones house their reproductive structure

32. Coniferophyta Cont’d...

33. PHYLUM CYCADOPHYTA

34. Classification of Cycadophyta Kingdom : Plantae Phylum: Cycadophyta Class: Cycadopsida Order: Cycadales Family: Cycadaceae Genus: Cycads

35. Phylum Cycadophyta Cycads are found in tropical forest and sub-tropical regions Second largest group of gymnosperms consisting of 11 genera and 140 species Pseudoparasitic which are epiphytic Evergreen gymnosperms

36. Cycadophyta Cont’d... Characterized by large croon of compound leaves Palm like or fernlike Dioecious Found in subtropical and tropical parts of the world Grow in semi-desert climates and in sand Carry on symbiotic relationship with bacteria

37. Cycadophyta Cont’d... These microbes produce toxins or poisons that accumulate in seeds These toxins are thought to provide protection against bacteria or fungal parasite seeds can be dangerous to humans or animals if they are ingested. Seeds are propagated by agents of pollination mainly wind

38. Insect Sitting On Cone To Pollinate

39. PHYLUM GINKGOPHYTA

40. Phylum Ginkgophyta Have only one extant species, named Ginkgo biloba Ginkgo comes from the Chinese word meaning “Silver apricot” (gin=silver, kyo = apricot). Biloba comes from the Latin meaning “double leaves ” (bi=double, loba = leaf. G.biloba is one of the oldest living tree species, over 300 million years ago. Individual tree can live for over 1000 years . Only one extant specie

41. Phylum Ginkgophyta Leaves are unique among seed plants, fan-shaped with veins radiating out into the leaf blade Ginkgo leaves are bi-lobed, tough and more resistant to decay than other leaves

42. Ginkgophyta Cont’d... Seeds Have fleshy coats, but they are not like the true fruits of Angiosperms They are attractive in appearance, but contains butanoic acid and have a bad odor like rancid butter Ginkgos are dioecious

43. Ginkgophyta Cont’d.. Vascular system of ginkgos , and also conifers, are different to that of flowering plants Flowering plants have a series of tube-like cells to conduct water. Ginkgos have connecting cells with tiny perforations These are valves(perforations) that close when water is in short supply so that turgidity is preserved Ginkgos have a tendency to put out suckers from the ground

44. Ginkgophyta Cont’d... O lder trees sometimes also have odd downward growths, called Chichi They grow from a damaged stem or by putting out new shoots from the ground When these growths hit the ground they can start growing new roots and eventually form into a new tree this seems to be a form of reproduction for when the main tree is coming to the end of its life, or when there are no females around.

45. Example of Chichi on Ginkgo

46. Phylum Gnetophyta

47. Phylum Gnetophyta Gnetophyta are small group of vascular seed plants composing one of the four phylum of gymnosperm They include 70 species divided into three: Ephedra, Gnetum , and Welwitschia They have more angiosperm like features than any other gymnosperms Welwitschia and Gnetum are similar to flowering plants: not having archegonia, and some species of Ephedra and Gnetum are the only plants to go through double fertilization.

48. Phylum Gnetophyta: Gnetum species Gnetum are mostly vines or shrubs 30 species They are found in South Asia, Tropical Africa, and Amazon basin Their leaves are broad and resemble flowering plants Their seeds are eaten Gnetum seeds Gnetum specie

49. Phylum Gnetophyta: Ephedra Species Ephedra known as Mormon tea or joint firs 30 species They are found in Northern Mexico and South Western US S trobili usually emerge from the axils of leaves Some species undergo double fertilization

50. Phylum Gnetophyta: Welwitschia Species Welwitschia contains only one species (Welwitschia mirabilis) They are found in South Western Africa They survives in extremely drought Their leaves grow perennially and they are larger They have the largest leaves in the plant kingdom

51. Welwitschia Species In A Xerophytic Environment

52. Importance of Gymnosperms

53. Importance of Gymnosperms They importance of gymnosperms are categorized into the following group Industrial value Ornamental value Food value Medicinal value Timber value Source of oil

54. I mportance of Gymnosperms F ood Value Cycads are good source of starch, that is obtained from Cycas rumphi , which is processed into flour Seeds of Pinus gerardiana and Gnetum seeds are edible known as chillgoza Kaffir bread is a type of bread prepared from the stem pith of Encephalatos Young leaves of cycas are cooked as vegetables in some parts of the world

55. Importance of Gymnosperms Medicinal value Paclitaxel (PTX) sold under the name Taxol, used for chemotherapy against cancer Ephedrine is an alkaloid extracted from the Ephedra. It is used in the treatment of asthma, cough, cold, bronchitis . Juice from the young leave of the phylum Cycas revoluta is used for curing blood vomiting . Cycas guns: is an antidote against snake bite and it is also used to cure malignant ulcer .

56. Importance of Gymnosperms Timber value Gymnosperms are a good source of timbers; they are mainly softwood which is beneficial in furniture settings and construction purposes The woods from conifers are resistant to insects and fungus Woods from Gymnosperms are also durable and of light weight A specie of gymnosperm called Agathis australis is the largest timber producing tree in the world Plywoods and other scented woods are all products processed from Gymnosperms.

57. Importance of Gymnosperms Source of Oil Edible oil is extracted from the seeds of Cycas revoluta, macrozania and many others Red cedar wood oil is extracted from the heartwood of juniperus virginiana is used in oil immersion microscopy . Oil from Gymnosperms are also used in deodorants and soaps

58. Importance of Gymnosperms Industrial value Tannins extracted from the bark of pinus and sequoia are used in the leather industry Newspapers, writing papers, and printing papers are prepared from the wood pulp of pinus, picea and abies

59. Importance of Gymnosperms Ornamental Value Ornamental plants are plants that are grown for decorative purposes Ginkgo and other pines, cycads and Gnetum species used in decoration of lawn, parks etc.. Various species of gymnosperms can also be grown as Bonsai

60. Importance of Gymnosperms Gymnosperms Used as Ornaments

61. In Conclusion: Gymnosperms are under the group sub group of plants called the phanerogams T hey are non-flowering, but seed bearing . T hat they are photosynthetic in nature. Cycads , conifers, ginkos and gnetophytes are four groups of plants that are closely related, which forms the four main categories of gymnosperm. These categories of plants are useful to mankind both in medicine, food, and the ecosystem.

62. Reference Nabor, Murray W., INTRODUCTION TO BOTANY, Copyright 2004 Pearson Education, Inc., publishing as Benjamin Cummings, 1301 Sansome St., San Francisco, CA 94111 www.khanacademy.org/science/biology/gymnosperms-in-plants/discussion/--c3-c4-andcycads/conifers-gneptosida-- and-plants-agriculture http://www.svenlandrein.com/systematiccoursepages/gymno

63. ‘Always learn to be a smart student’ - Mr. Fasama H. Kollie Rocky productions

64. Questions ! Comments!!