Early vascular plants fossil record

1
Early vascular plants (fossil record)

• branched sporophytes
• dichotomous branching
• terminal sporangia
• rhizome horizontal stem
• still attached via rhizoids
• eventually roots, evolved
• stem but no leaves
• lignified water conducting cells

2
modern seedless vascular plants (grade not
clade)

• branched sporophytes
• dichotomous branching in lycophytes
• non-dichotomous branching in ferns
• subterminal sporangia
• rhizomes roots
• leaves
• microphylls (one vein) in lycophytes
• megaphylls (branched veins) in ferns
• sporophylls leaves that bear sporangia
• lignified water conducting cells

3
life cycle of seedless vascular plants

• gametophyte small, short-lived
• sporophyte prominent
• specialization for spore dispersal

4
bryophytes seedless vasc plants

• gphyte prominent sphyte prominent
• no lignified vasc. tissue xylem w/lignin
• rhizoids in gametophyte rhizoids in gphyte
• roots in
  sporophyte
• poikilohydry homeohydry
• spores for dispersal
• water for fertilization

5
spores in vascular plants homospory
heterospory
one type of sporangium spore gametophyte
w/archegonia antheridia gametophytes develop
outside spore wall some lycophytes, most ferns
megasporangium w/ megaspores (food) --gt gphyte
w/archegonia microsporangium w/ microspores
(flight) --gt gphyte w/antheridia gametophytes
develop inside spore wall most
lycophytes, water ferns arose several times 1st
step in evol of seeds
6
extant seedless vascular plants

• 1. lycophytes
• Lycopodium and relatives
• temperate forest floor, bogs
• tropical epiphytes
• Selaginella diverse habitats
• Selaginella moellendorffii model organism
• Selaginella lepidophylla resurrection plant
• Isoetes
• big fossil trees

7
extant seedless vascular plants

• 2. Pterophytes (ferns) including
• Psilotum (whisk fern)
• Equisetum (horsetail, scouring rush)
• big fossil trees
• tree ferns, water ferns

8
fossil seedless vascular plants

• Carboniferous forests 290-360 mya
• fossil fuels (esp. coal)
• plants died, didnt decay (stored C)
• global cooling
• coal ball rock w/fossil plants
• NOT compressed into coal
• macrofossils w/fine details preserved