1. Seedless vascular plants
Lecturer: Asst. Prof. Dr. İsmail EKER

2. GENERAL CHARACTERISTICS OF SEEDLESS VASCULAR PLANTS
Vascular tissue
leaves with waxy cuticles and stomata
depend on water for reproduction and nourishment
Sporophyte is dominant and can grow independent of gametophyte
There are two types of leaves that may be found on seedless vascular plants
Microphylls
Small and have a single vascular strand
Club mosses, horsetails
Microphylls are thought to have evolved as extensions of stems
Megaphylls are thought to have evolved from stem branchings that filled in with an additional webbing and perhaps in response to decreases in carbon dioxide
Megaphylls
Larger and have more than one vascular strand
Plants needed a flattened blade with more stomata for gas exchange
Ferns

3. SYSTEMATICS OF SEEDLESS VASCULAR PLANTS
Phylum Psilophyta (whisk ferns)
Phylum Lycophyta= Lycopodophyta (club mosses)
Phylum Sphenophyta= Equsetophyta (horsetails)
Phylum Pterophyta= Pterodophyta (ferns)

4. Pterophyta (ferns) Largest and most diverse SVP group (12,000 species)
-Mostly terrestrial, Few are aquatic
Mainly tropical, but many in temperate zone
Make true leaves (megaphylls), stems, roots on sporophyte
- Have xylem and phloem tissue
Gametophytes small, reduced, independent
sporophylls with spores arranged in sori
Fern
gametophyte

5. fiddleheads are young fronds; sori appear on the fronds and house spores

6. The Sporophyte continues to grow while the Gametophyte dies.

7. Life cycle of Ferns
Spores (n) germinate into a prothallus (n) which will produce eggs (n) in the archegonium and sperm (n) in the antheridium they combine to form a zygote (2n)
the zygote grows into a young sporophyte (2n)
the mature sporophyte of most ferns produce only one type of spore (homosporous- one spore type produced and released); some are heterosporous, that is they produce two spore types, one developing into a male gametophyte, the other into a female gametophyte
Water is required for the sperm to use as a medium to swim to the egg

8. Sporangia often on underside of leaves
If in patch, patch called sorus (plural: sori)
Some patches covered with tissue (indusium).
These sori are uncovered (naked)
Each sorus here covered by indusium

11. Closeup of sorus with indusium (rounded structures are sporangia).

14. Polypodium

16. Phyllitis

17. Adiantum

18. Asplenium

19. Azolla- aquatic fern

20. Stenophyta (horsetails)
Once dominant plants in the landscape, 300my ago
Equisetum (horsetail/scouring rush) only living genus with 15 species
True roots, stems and small leaves (reduced megaphylls= microphylls); hollow jointed stems impregnated with silica; green stem main photosynthesizing part
The silica gives horsetails a gritty texture which American pioneers utilized as pot and pan scrubbers
Reproductive branches bear a terminal cone-like strobilus
Life cycle is similar to fern life cycle; also requires water

21. Gametophytes small (several mm long), green, independent of sporophyte.
Sporangia on underside of stalked structures called sporangiophores
Clustered in strobilus at stem tip.

22. Some horsetails change their appearance between spring and summer
Some horsetails change their appearance between spring and summer. Left: Horsetails in early spring make and disperse spores Right: In late spring, bushy green stems carry on photosynthesis.

25. Lycophyta (club mosses)
Second largest SVP group – Club mosses, spike mosses, quillworts – 1200 spp.
grew to 35m tall; some are epiphytes (on other plants), quillworts are aquatic
Sporophytes with branching stems and tiny, scale-like sterile leaves (microphylls), roots
Produce clusters of sporophylls (fertile leaves; spore-bearing leaves) called strobilus (pl. strobili)
Some are homosporous, some are heterosporous; If heterosporous, male microspores (n) will be produced along with female megaspores (n); once shed, these spores will develop into male and female gametophytes which will produce sperm and egg respectively; when the egg is fertilized a sporophyte (2n) will form; within the strobilus spores form and the process repeats
Like ferns and horsetails, club mosses have both an asexual and sexual stage in their life cycle. But the life cycle of a club moss may take as long as 15 years to complete!

26. It is a small evergreen plant that looked like the plant
It is a small evergreen plant that looked like the plant. This plant has small mosslike leaves that are closely arranged on its stem. On top of the plant is a club-shaped structure. For these reasons, this plant is named a club moss. In fact, some club mosses look so much like young pine trees that people call them ground pine.

27. Sporangia produced on leaves called sporophylls
Sometimes sporophylls clustered into a group called strobilus.

28. Lycopodium

29. Selaginella

31. Isoetes

33. Psilophyta (whisk ferns)
Small group (about 6 species) and Most are extinct
Simplest vascular plants
Very primitive vascular plant; simple sporophyte bodies: just erect stems. No leaves or roots. They have absortive rhizoids with mycorrhizae, stems, and leaflike structures
Stems with dichotomous branching (evenly split into two smaller stems). Consists of dichotomously branching rhizomes
Stems are the main photosynthetic organ

34. Psilotum sp. growing in crack of rock
Psilotum branches dichotomously (lumps are sporangia)

35. Sporangia on aerial stems
Underground stems called rhizomes: have filamentous rhizoids.
Closed (top) and split (bottom) sporangia on stem

37. Importance of Seedless Vascular Plants
Roles in the Environment:
Ferns, horsetails, and club mosses help form soil
Help prevent soil erosion
Ferns can play a role in the formation of communities in rocky areas
Primary producers (important part of biomass of some habitats).
Fern forest in Tasmania, Australia

38. Economical importance: Fossil SVPs
Coal: Eventually the pressure and heat changed the ferns and other plants into coal, oil, and natural gas.
Dominated land during Carboniferous Period ( million years ago)
Vital source of energy today!
Vital source of energy today! (“Fossil fuel”)
>50% of U.S. electricity.
Coal seam
in western
U.S. desert
Mining coal for power

39. Coal is incompletely decomposed carbon from ancient plants (burns!).
The remains of ancient ferns, horsetails, and club mosses formed coal.

40. Fiddleheads of some ferns can be cooked and eaten

41. Ferns and some club mosses are popular houseplants and floral arrangements (indoor and outdoor).
Horsetails are used in some dietary supplements, shampoos, and skin-care products.
Maidenhair fern
Lady fern

42. KEYWORDS OF VASCULAR PLANTS
Homospory
The production of one kind of spore
Bryophytes
Whisk ferns
Horsetails
Most club mosses
Most ferns
Spore gives rise to gametophyte plants that produce both egg and sperm cells.

43. KEYWORDS OF VASCULAR PLANTS II
Heterospory
Production of two kinds of spores
Microspores
Give rise to male gametophytes that produce sperm cells
Megaspores
Give rise to female gametophytes that produce eggs.
Occurs in
Certain club mosses
Certain ferns
ALL SEED PLANTS.
The “evolution” of heterospory was an essential step in the evolution of seeds.

44. Artist’s conception of a Carboniferous forest based on fossil evidence

46. Pop music megastar Lady Gaga is being honored with the name of a new genus of ferns found in Central and South America, Mexico, Arizona, and Texas in A genus is a group of closely related species; in this case, 19 species of ferns will carry the name Gaga. At one stage of its life, the new genus Gaga has somewhat fluid definitions of gender and bears a striking resemblance to one of Gaga's famous costumes. Two of the species in the Gaga genus are new to science: Gaga germanotta from Costa Rica is named to honor the family of the artist, who was born Stefani Germanotta. And a newly discovered Mexican species is being dubbed Gaga monstraparva (literally monster-little) in honor of Gaga's fans, whom she calls “little monsters.”