concept 29.4
TRANSCRIPT
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?