Concept 29.4

CONCEPT 29.4: FERNS AND OTHER SEEDLESS VASCULAR PLANTS FORMED THE FIRST FORESTS!Benjamin H.

Michelle K.

SEEDLESS VASCULAR PLANTS

Carboniferous period: vascular plants diversified

Fragile gametophytes Sperm must swim Most common in damp environments

ORIGINS AND TRAITS OF VASCULAR PLANTS

420 million yra Branched sporophytes

Not dependent on gametophytes Complex bodies with multiple sporangia

LIFE CYCLE WITH DOMINANT SPOROPHYTES

Sporophyte: larger + more complex

Sporophyte

TRANSPORT IN XYLEM AND PHLOEM Vascular tissue Xylem: conducts water + minerals

Tracheids: tube-shape cellsd (dead cells) Lignin: polymer, strengthens cell walls

Phloem: distributes organic products Transport materials above ground w/ lignin plant = stronger

EVOLUTION OF ROOTS

Roots: organs, anchor plants, absorb water and nutrients from soil

Early roots resemble stem tissue

Evolve from lower, underground stems

Convergent evolution?

EVOLUTION OF LEAVES

Leaves: organs, increase surface area for photosynthesis

Microphylls: small, one vein Megaphylls: leaves w/ highly branched

vascular system, more photosynthesis

SPOROPHYLLS

Sporophylls: modified leaves w/ sporangia Sori: clusters of sporangia Strobili: cones, groups of sporophylls

SPORE VARIATIONS

Homosporous:

1 sporangium 1 spore bisexual gametophyte eggs and sperm

Heterosporous:

Megasporangium megaspore female gametophyte eggs

Microsporangium microscope male gametophyte sperm

LYCOPHYTES

Use other plants as substrates tiny gametophytes Sporophytes

Upright stems, many small leaves In mosses, clustered in strobili (club-shape

cones) Club mosses, spike mosses, quillworts

PTEROPHYTA

Whisk ferns Branching stems No roots or leaves

Horsetails Bushy stems Homosporous Stems w/ joints (stem = main photosynthesis)

Ferns Megaphylls Horizontal stems w/ large leaves (fronds) Homosporous

SIGNIFICANCE OF SEEDLESS VASCULAR PLANTS

During Carboniferous period grew tall Formed forests Accelerate photosynthesis Removed CO2 from atmosphere peat, became coal

REVIEW!

What’s the phenolic polymer that strengthens cell walls?

What do megasporangium produce? What do microsporangium produce? What vascular tissue transports water and

minerals? What vascular tissue transports organic

products? What is the significance of these vascular

plants?