SEEDLESS VASCULAR PLANTSPacket #70

Chapter #29

THE THEORY OF EVOLUTION CONNECTION

Seedless vascular plants arose in the Carboniferous Period 420 – 360 mya Phylum Rhinophyta are known as the oldest

seedless vascular plants These organisms left relics, fossils and coals Scientists believe that seed plants were

present during this evolutionary time period but were not dominant.

Seedless vascular plants became important as the swamps dried up and the global climate cooled.

TYPES OF SEEDLESS VASCULAR PLANTS

There are four phyla of seedless vascular plants. Phylum Polypodiophyta

Ferns Phylum Psilotophyta

Whisk ferns Phylum Equisetophyta

Horsetail Phylum Lycophyta

Club Mosses

IMPORTANT INFORMATION FOR VASCULAR PLANTS

LEAVES OF VASCULAR PLANTS

There are two types of leaves that may be found on seedless vascular plants Microphylls

Small and have a single vascular strand

Club mosses Megaphylls

Larger and have more than one vascular strand

Plants needed a flattened blade with more stomata for gas exchange

Ferns, horsetails and seed plants

Leaves of Vascular Plants Microphylls

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.

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.

SEED VASCULAR PLANTS—FERNS

PHYLUM PTEROPHYTASUBPHYLUM POLYPOIOPHYTATHE FERNS Largest and most

diverse group of seedless vascular plants. Have xylem and

phloem tissue Most have true roots More than 12,000

species have been described.

PHYLUM PTEROPHYTASUBPHYLUM POLYPOIOPHYTATHE FERNS Almost all species

are homosporous All have megaphylls. Found primarily in

moist tropical habitats Few are aquatic

FERNSFEATURES THAT DISTINGUISH FERNS AND OTHER SEEDLESS VASCULAR PLANTS FROM ALGAE AND BRYOPHYTES.

Comparison to Bryophytes Ferns have vascular

tissue Ferns have a

dominant sporophyte generation.

As in bryophytes, reproduction in ferns depends on water as a transport medium for their motile sperm cells.

REPRODUCTIVE CYCLE OF FERNS

PHYLUM PTEROPHYTASUBPHYLUM POLYPOIOPHYTATHE FERNS

Ferns display alternation of generation and they have a dominant sporophyte generation

Fern bodies consist of a rhizome (an underground stem), roots, and leaves (megaphylls).

Figure 29.12Page 585

PHYLUM PTEROPHYTASUBPHYLUM POLYPOIOPHYTATHE FERNS Sprophytes have

roots, rhizomes and leaves that are megaphylls.

Leaves, or fronds, bear sporangia in clusters called sori.

Meiosis of sporangia produces haploid spores.

PHYLUM PTEROPHYTASUBPHYLUM POLYPOIOPHYTATHE FERNS Spore germinates and

grow via mitosis into a gametophyte called haploid prothallus. Heart shaped and lacks

vascular tissue Anchored by rhizoids Bears antheridia and

archegonia Water is still required

for transportation of the flagellated sperm to the archegonium

Zygote grows into free-living sporophyte plant.

SEEDLESS VASCULAR PLANTS—WHISK FERNS

PHYLUM PTEROPHYTA SUBPHYLUM PSILOTOPHYTATHE WHISK FERNS Simplest vascular

plants Lack true roots and

leaves Consists of

dichotomously branching rhizomes

Have erect stems. Homosporous

sporophylls.

SEEDLESS VASCULAR PLANTS—HORSETAILS

PHYLUM PTEROPHYTASUBPHYLUM EQUISETOPHYTATHE HORSETAILS

Sporophytes have roots

Rhizomes Aerial stems

Hollow and jointed Leaves that are

reduced megaphylls

SEEDLESS VASCULAR PLANTS—CLUB MOSSES

PHYLUM LYCOPHYTATHE CLUB MOSSES

Small plants with rhizomes and short erect branches

Extant species have true roots and leaves that are microphylls.

REVIEW

REVIEW

Students List potential examination questions and/or here,

and on following slides, based on the packet.