Bryophytes are the simplest plants

bryophytes

seedless plants that lack vascular tissue

1. but evidence suggest that they do not even form a single clade

2. lack vascular tissue and it’s associated lignin —> therefore lack support

3. Usually small and compact plants

4. lack true roots and leaves, but many have structures tat are superficially similar to these organs

   1. ex. photosynthesis occurs at flattened leaf-like structures

small size

means that each cell can absorb minerals and water directly from it’s surroundings

1. materials move from cell to cell within the plant by diffusion and osmosis

   1. NOT WITHIN SPECIALIZED TRANSPORT TISSUES

rhizoids

hair-like extentions that cover a bryopahte’s lower surface, anchording the plant to it’s substrates

1. cannot tap distance sources of water

   1. therefore restricts most to moist, shady habitats that are unlikely to dry out

24,000

About how many bryophytes are there?

liverworts

phylum Marchanotiopyhyta

1. have a variety of gametophyte forms, from flat to upright and leafy

2. may be the bryophytes most closely related to ancestral land plants

hornworts

Phylum Anthocerotophyta

1. the smallest group of bryophytes, with only about 100 species

2. They are named for their sporophytes, which are shaped like tapered horns

mosses

Phylum Bryophyta

1. the closest living relatives to the vascular plants

2. their gametophytes resemble short “stems” with many “leaves”

organic matter

When bryophyte tissues die, what do they contribute to soil that helps larger plants to subsequently colonize?

bryophytes repoduce

asexually or sexually

asexual reproduction

in liverworts, occurs in gemmae

1. mosses also produce gemmae

gemmae

small pieces of tissue that detach and grow into new plants

sporophyte

a stalk attached to the gametophyte

1. tip of the stalk - specialized cells inside sprangium undergo meiosis and produce haploid spores

   1. after the spores are released, they germinate, giving rise to new haploid gametophytes

      1. sperm swims to eggs in a film of water that coats the plants

water

sexual reproduction in plants requires what?

1. this limits plants to moist areas

sporophyte generation

begins at fertilization, with the formation of the diploid cekk

1. the cell divides mitotically, producing the sporopyte’s stalk

fossils

Thanks to thick stalks providing against drying out, bryopyte spores are preserves in