1. Seedless Vascular Plants Chapter 17

2. Seedless vascular plants The descendants of certain lineages of seedless vascular plants, with names such as whisk ferns, lycophytes, horsetails, and ferns,

4. Seedless Vascular Plants differ from bryophytes in that the sporophyte does not remain attached to the gametophyte (is free-living) and has well-developed vascular tissues. It is the larger, longer lived phase of the life cycle.

5. Organization of the Vascular plant body The sporophytes of early vascular plants were dichotomously branched Club moss sporophyte

6. Young Club moss sporophyte Shoot system Vascular system

7. Tissue systems Dermal- outer portion Vascular- conductive tissues (xylem and phloem) Ground- vascular embedded within ground Root, stem and leaf vary in these tissues

12. Vascular Tissue Approximately 93% of plant species are vascular plants. Vascular plants contain vascular tissue. There are two kinds of vascular tissue: Xylem conducts water and minerals up from the soil. The cell walls of xylem cells help support the plant. Phloem conducts organic nutrients from one part of the plant to another. True roots, stems, and leaves are found only in vascular plants because these structures must contain vascular tissue. The sporophyte of vascular plants is dominant.

13. Gametophytes Although the sporophytes of seedless vascular plants can live on land, their gametophytes cannot because they lack vascular tissues and the male gametes must have water to reach the eggs. Seedless vascular plants typically live in wet, humid places.

14. Tracheids elements Conducting cells of the xylem (water and minerals) Have lignified wall thickening

15. Sieve elements In contrast sieve elements, the conducting cells of the phloem have soft walls and often collapse after they die

16. Vessel elements Principle water conducting cells in angiosperm (flowering plants) VE evolved independently in several groups of vascular plants- Convergent evolution

17. Vascular tissue Located in the vascular cylinders or Steles of Roots and Stems Primary xylem Primary phloem In some Vascular plants Pith (ground tissue)

18. Vascular tissue

19. Several types of Steles- vascular cylinders that contain vascular tissue (xylem, phloem and ground tissue) Leaf precursors Found in SVP

20. Two distinct kinds of leaves (phylls) Microphylls- small leaves contain single strand of vascular tissue (Isoetes – long leaves) Megaphylls- associated with stems that have either siphonosteles and eusteles Branching veins

21. Reproductive Systems All vascular plants are oogamous- have large nonmotile eggs and small sperm that swim or are conveyed to the egg All VP have an alternation of heteromorphic generations ( sporophyte is larger and more complex than the gametophyte)

22. Generalized life cycle of a vascular plant Larger and more complex than the gametophyte Free living

23. Oogamy Favored in plants Only one of the kinds of gamete must navigate across a hostile environment

24. Homosporous Vs Heterosporous Homosporous produces one type of spore Heterosporous produces two types of spores Early vascular plants are homosporous i.e. (including horsetails) and some lycophytes Heterosporous found in some lycophytes and in all seed plants (convergent evolution)

25. Microspores and Megaspores Microspores- male gametophyte Megaspores- female gametophyte Endosporic development (develop within spore wall) unlike the homosporous development

26. Evolution of the vascular plant The gametophytes of VP have become smaller and simpler Relatively large gametophytes of Homosporous plants are independent of the sporophyte for their nutrition In contrast the gametophyte of many heterosporous VP and seed plants are dependent on the sporophyte for their nutrition

27. The Living Phyla of Seedless Vascular Plants Phylum Lycopodiophyta –Club mosses –Lycopodium lagopus –Selaginella –Isoetes Phylum Pteridophyta – Ferns –Water ferns- orders Marsileales and Salviniales –Psilotales –Equisetales (horsetail)

28. Phylum Lycopodiophyta Lycophytes were once tree-sized but now are represented by small club mosses on the forest floor. The sporophyte has true roots, stems, and small leaves containing the vascular tissue. Strobili bear spores that germinate to form small, free-living gametophytes.

29. Family Lycopodiaceae - Club mosses Most familiar type in Lycopodiophyta phylum

30. homosporic

31. Huperzia lucidula- lack strobili Lycopodium lagopus- have strobili

32. Family Selaginellaceae Selaginella lepidophylla - resurrection plant

33. Selaginella rupestris- rock spikemoss

34. Selaginella kraussiana- creeping plant

35. Selaginella willdenovii

36. Selaginella is heterosporic

38. Family Isoetaceae- Quillworts Last remnant of the fossil tree lycopods Lepidodendron (also known as the "Scale tree") because of their peculiar secondary growth- development of both wood and bark, a modified shoot system and an upright stance. heterosporic presence of ligules May be aquatic

39. Phylum Pteridophyta Ferns (Pterophyta)Ferns (Pterophyta) Most ferns have a perennial underground stem (called a rhizome). Roots and fronds arise from the rhizome. Young fronds are coiled "fiddleheads". Mature fronds are divided into leaflets. Spores form on the lower surface of some fronds. Sori are clusters of sporangia that release spores that develop into small heart-shaped gametophytes.Sori gametophytes.

40. Phylum Pterophyta

41. Order Filicales Homosporic Most familiar order

42. Life cycle of a fern Life cycle of a fern Order Filicales (polypodium) homosporic

43. In most ferns, the stem is a horizontal, underground structure called a rhizome. The leaves grow above-ground (see the photograph above). A sorus (pl. sori) is a cluster of sporangia. Sori are located on the underside of the leaves.

46. VIDEO - Fern sporangia discharge (X40) (4.13 MB)

47. Water Ferns- Order Marsileales and Salviniales Marsilea polycarpa Salvinia natans Water ferns are heterosporic

48. The equisetophytes- Equisetum- horsetails Damp areas Streams Along edge of woods Jointed stems and rough texture Small scalelike leaves whorled at nodes