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…