1. Plants II The Vascular Plants Hypericum sp. Photo by Alan Mulvey THE SEED PLANTS I Gymnosperms

3. Evolution of the Seed Plants  Heterosporous  Seed: (embryo & stored food)  Evolution of pollen Megagametophyte develops within ovule** Microgametophyte develops within pollen grain** Pollen grains evolved by reduction of male gametophyte & protection by pollen walls Both the male & female gametophytes were retained within the sporophytes

4. Evolution of the seed  One cell megaspore is retained within megasporangium  It is protected by integument  It develops into mature megagametophyte within the embryo sac  After fertilization, it matures into the embryo (sporophyte)

5. Lilium: Pollen Generative cell ( 2 sperms ) Tube cell Pollen wall

6. Pine: Pollen Generative cell Tube cell Wings

7. Evolutionary transition from a gametophyte to sporophyte dominance From Keeton, 1993

8. The Gymnosperms: Characteristics  (naked seed)**  Water is not required for fertilization  Mainly pollinated by wind  Reproductive changes increased protection of gametes  Have sunken stoma & thicker cuticles

9. Seed Cone Cone Scale Two Seeds per Scale

10. Pine: Leaf Sunken Soma EpidermisHypodermis

11. Characteristics Cont..  Have secondary growth - all trees or shrubs  Mostly evergreen  Xylem has tracheids, lacks vessels (except some Gnetophytes)  Phloem has sieve cells, lacks sieve tube members

12. Progymnosperms  An extinct group that arose in late Paleozoic  Intermediate between seedless & seed plants  Progymnosperms were ancestors of seed plants  Evolved bifacial V.C. & wood (page 411)

13. Seed Plants I - Gymnosperms  Conifers – Coniferophyta  Cycads – Cycadophyta  Maidenhair tree – Ginkgophyta  Gnetophytes – Gnetophyta

14. Conifers: Phylum Coniferophyta  evolved 290 MYO  Constitute the largest group of gymnosperms (50 genera, 550 spp.)  Include the tallest & largest trees ever (Giant redwood)  Conifers (pine, fir, spruce) have great commercial value in temperate zones  Leaves are either needles, long or short, as in pines, fir, spruce small flat, scale-like as in junipers, cypresses  Mostly evergreen, monoecious

15. White Pine: Pinus strobus

16. White Pine

17. : Twig &Needles White Pine : Twig &Needles

18. White Pine Pollen ConesSeed Cone

19. Longleaf Pine: Pinus palustris

20. Loblolly Pine: P. taeda

21. Loblolly Pine: Pollen Cones

22. Slash Pine: P. elliottii Turpentine Production

24. Bald Cyprus Knees: Taxodium distichum Knees

25. Bald Cyprus

27. Bald Cyprus: Crown & Seed Cones

28. Coast Red Wood: Sequoia sempervirens Fossil

29. Sequoia: Coast Red Wood

30. Giant Red Wood Sequoia http://www.habitas.org.uk/gardenflora/sequoiadendron.htm

31. Giant Red Wood Seed Cones Pollen Cones http://www.conifers.org/cu/se2/

32. Balsam Fir: Abies balsamea

33. Balsam Fir Seed Cone Leaves

34. Larch: Larix decidua

35. Larch Developing cones

36. Common Juniper: Juniperus communis Tree Leaves

37. Juniperus virginiana (Eastern Red Cedar) Juniperus virginiana (Eastern Red Cedar) Cones

38. Hemlock: Tsuga canadensis

39. Hemlock: Leaf & Cone

40. White Spruce: Picea glauca

41. Pollen cones Young seed cones Pollinated seed cones White Spruce

42. Pacific yew: Taxus brevifolia http://www.fw.vt.edu/dendro/dendrology/syllabus/tbrevifolia.htm

43. Maidenhair tree Phylum Ginkgophyta:  One extant species, Ginkgo biloba (notched leaf)**  Reproduction is dioecious  Ginkgo is resistant to air pollution (city parks)  Pickled seeds are eaten in Asia  Ginkgo is now cultivated, could be in the wild (Asia)

44. Ginkgo biloba Leaves are broad with dichotomous venation

45. The Ginkgo tree has properties which make it resistant to nuclear radiation. This tree survived the Hiroshima bombings. www.ginkgo.co.nz/images/ large/ginkgotree.jpg

46. Ginkgo biloba

50. Male cones Sperms are flagellated, borne in cone-like structure

51. Ginkgo Brach & Fruit

52. Ginkgo Seed Cones  The fleshy part which covers the seed is the integument (offensive odor)  No cones but ovules are borne in pairs and stalked

53. Cycads: Phylum Cycadophyta  About 250 MYO, common during the Mesozoic (age of cycads & Dinosaurs)**  Constitute 11 genera (140 spp)  Tropical or subtropical  Zamia, the only cycad in the States, is native to Florida  Most cycads are large palm-like plants  Highly toxic (produce neurotoxins & carcinogenic compounds)  Sperms are motile, but they are pollinated by beetles  Dioecious

54. Cycad: Encephalartos humlis

55. Zamia floridana http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/cycadpg?taxname=Zamia+pumila Male/female cones

56. Zamia: Cones Male Female

57. Cycad: Encephalartos altensteinii http://www.calflora.net/southafrica/pageseventeen.html

58. Cycad: Encephalartos ferox Native to Africa

59. Encephalartos ferox

61. Gnetophytes: Phylum Gnetophyta  Comprise 3 genera (70 spp)  The most derived group of gymnosperms  Similarities to angiosperms:  Produce vessels (in xylem)  Their strobili are similar to angiosperms’ inflorescence  Double fertilization in Ephedra & Gnetum  Produce nectar & insects play a role in pollination  Leaves are borne in opposite pairs

62. The genus Gnetum  Has 30 spp (trees & woody vines)*)*  Native to SE Asia, tropical Africa, Amazon basin  Have broad leathery leaves similar to dicot.

63. Gnetum gnemon

64. Gnetum: Leaf

65. Gnetum: Pollen Cones

66. Gnetum: Seed Cones

67. The genus Ephedra  Has 35 spp  Tough shrubs inhabit deserts in N Mexico and SE USA**  Leaves reduced and scale-like  Dioecious or monoecious

68. Ephedra - Cures respiratory problems - Used in weight loss prog. - A stimulant

69. Ephedra: Pollen Cones

70. Welwitschia mirabilis  The most bizarre vascular plant**  Native only to deserts of South Africa, Angola, & Namibia  Dioecious

71. Welwitschia - Most of the plant is buried in the sand - Aboveground discoid wide stem (1.5 m wide) produces 2 long leaves DISK

72. Welwitschia Habitat http://www.csdl.tamu.edu/FLORA/imaxxwlw.htm Population

73. Welwitschia Habitat

74. Welwitschia Cones

75. Welwitschia Male conesFemale cones