BIOL 2P93 Lecture Notes - Lecture 9: Marchantia, Antheridium, Archegonium
22 Jan 2016
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Most liverwort gametophytes develop from spores + some first form protonema-like filament of cells mature gametophyte grow from an apical meristem. Liverworts make mucilage (highly hydrated polysaccharide) for water retention. Three major types of liverworts differ by structure. One w/ complex thalloid liverworts of internal tissue differ + other clade w/ leafy liverworts + simple thalloid liverworts, both have ribbons of undiffer tissue. We will consider marchantia sp. (complex thalloid liverwort). :thallus (gametophyte) of thalloid liverwort 30 cells thick at midrib + approx 10 cells thick in thinner portions. Differ into thin chlorophyll-rich upper (dorsal) portion + thicker, colorless lower (ventral) portion which bears rhizoids + rows of scales. Upper surface divided into raised regions, each w/ large pore leads to air chamber. G ametophyte (thalloid liverwort): note* numerous chloroplast-bearing cells in upper layers, w/ several layers of colorless cells below. Pores exchange of gases in air-filled chambers that dot upper photosynthetic layer.
