An Overview of Land Plant Evolution
(Ch. 29, Plant Diversity I) 1) origin from ancestors similar to
charophytes2) bryophytes3) ferns4) other spore-dispersed plants
1) origin from ancestors similar to charophytes…
The evolution of land plants involves changes in plant development related to reproductive biology.
Chara - a charophyte - the whole plant body is haploid except for the zygote
egg and sperm production close up
zygote
The origin of the land-plants includes a delay in meoisis, so that thereare diploid vegetative cells in the life cycle.
cuticle, a critical inventionfor land plants
1) origin from ancestors similar to charophytes…
1) origin from ancestors similar to charophytes…
Table 25.1, chapter 25, p. 515
Table 25.1, chapter 25, p. 515
An Overview of Land Plant Evolution
1) origin from ancestors similar to charophytes
2) bryophytes3) ferns4) other spore-dispersed plants
bryophytes:
• Ca. 15,000 species
• Gametophyte shoot with leaves is common.
• Unbranched sporophyte, which has stomates
MossLife Cycle
Spores produced in sporangium
A-C: Mosses
D,E: Liverworts
F, G: Hornworts
operculum
peristome teeth
Marchantia, a thallose liverwort
Bazzania, a leafy liverwort
archegonium of a liverwort
antheridium of a hornwort
sporophytes of two mosses
haircap moss
peat moss—Sphagnum
moss spores—products of meiosis
An Overview of Land Plant Evolution
1) origin from ancestors similar to charophytes
2) bryophytes3) ferns4) other spore-dispersed plants
Life cycle for the ferns
The ferns, with 12,000 species, are the most successful spore-dispersed vascular plants.
Most ferns have a creeping stem and divided leaves…
Vascular tissue—for moving fluids and providing structural support—is divided into xylem and phloem.
xylem
phloem
Sporangia are in groups called sori.
one sorus with sporangia hidden underneathan indusium
Spores are produced by meiosis in the sporangium.
Spores germinate to produce haploid gametophytes.
The gametophytes don’t have shoots or vascular tissue.
Fertilization
Fertilization yields new diploid sporophytes.
An Overview of Land Plant Evolution
1) origin from ancestors similar to charophytes
2) bryophytes3) ferns4) other spore-dispersed plants
1) origin from ancestors similar to charophytes…
the horsetails, Equisetum
a clubmoss, Lycopodium
a coal swamp, dominated by spore-dispersed plants
Table 25.1, chapter 25, p. 515
Fossil spore tetrads from the Cambrian are evidence of theorigin of the land-plant lineage and its life cycle:
Table 25.1, chapter 25, p. 487
Table 25.1, chapter 25, p. 487
1) origin from ancestors similar to charophytes…
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