Seedless Plants

Plant
Evolution

Plant Evolution
 Nonvascular Seedless plants
– (Ordovician - 475 mya)
 Vascular Seedless plants
– (Devonian - 400 mya)
 Vascular Seed plants
– (Carboniferous - 360 mya)
 Flowering plants
– (Cretaceous - 130 mya)

Plant Evolution
(Common with Algae)
 Multicellular and Eukaryotic
 Cell walls made of Cellulose
 Chlorophyll a and b
 Store excess sugar as starch

Adaptations to Terrestrial Life
 Apical Meristems
 Multicellular Dependent Embryos
 Alternation of Generation
 Walled Spores produced in Sporangia
 Other Adaptations
– Cuticle, stomata, Xylem & Phloem, secondary compounds

Apical Meristems

Multicellular Dependent
Embryos

Alternation of Generation

Walled Spores produced in
Sporangia

Other Adaptations

Adaptations in
Shallow Water Algae
 Subjected to occasional drying
 Protection of gametes and embryos in gametangia
 Sporopollenin


Classification of Seedless
Plants
Nonvascular Seedless plants
– Bryophyta
 Vascular Seedless plants
– Lycophyta
 Mosses
– Hepatophyta
 Liverworts
– Anthocerophyta
 Hornworts
 Club mosses
– Psilophyta
 Whiskferns
– Spenophyta
 Horsetails
– Pterophyta
 Ferns

Nonvascular Seedless Plants
 Plant is a thallus (no vascular tissue)
– no true leaves, roots, stems
 Embryophytes
– gametangia
 (antheridium and archegonium)
– sporangium (produces spores)

Hepatophyta
 Liverworts
– Two forms
 leafy (80%)
 thalloid (20%)

Hepatophyta
 Liverworts
– Reproduction
 asexual
(gemmae cups)
 sexual

Anthocerophyta
 Hornworts
– Similar to liverworts except for sporophytes
– Most closely related to higher plants

Bryophyta
Mosses

Bryophyta
Mosses

Vascular Seedless Plants
 Formation of vascular tissue
– Xylem (water)
– Phloem (food)
– True leaves, roots, and stems
 Lignin
 Sporophyte generation dominate
 Sperm with flagella

Lycophyta
 Lycophytes
– true leaves
 microphylls
– true stems
– true roots
– sporophylls
 leaves that produce spores

Psilophyta
 Whisk Ferns
– no true leaves
– no true roots

Sphenophyta
 Horsetails
– true leaves
 microphylls
– true stems
 silica
– true roots

Division: Pterophyta

Division: Pterophyta

Fern Life Cycle