BIOL 1030 Lecture Notes - Meiosis, Mycelium, Polytrichum
Lectures 23-24: Intro to land plants, bryophytes, seedless vascular plants (29.1-3)!
Lecture 23: The Bryophytes
6 main traits of bryophytes!
I. Life cycle has dominant gametophyte phase!
II. No xylem or phloem!
III. No roots (limited to live close to water)!
IV. No leaves!
V. No cuticle (no resistance to water loss)!
VI. Sporophyte is dependent on the female gametophyte for nutrition, this stage is short-lived!
"Polytrichum haircap moss thallus:!
Entire thallus can absorb water, minerals, have gas exchange and undergo photosynthesis
"Mature Sporophyte:!
-Foot: receives nutrients transported from the female gametophyte!
-Seta: elongated stalk that raises up spore bearing capsule for dispersal!
-Sporangium: site of meiosis; where a young sporophyte cell (2n) becomes spores (n).!
"Under cap: peristome, open and closes with humidity to disperse and dispense spores,
wind is good. The spore giving rise to a new (n) phase.!
Dioecious - 2 houses, male gametes and female gametes; separate male and female plant
gametophytes.!
Gametophore: sexually mature gametophyte!
Gamete transfer occurs with motile sperm transported to the archegonium by water (down
the neck, to the venter, to the egg cell (archegonia)!
"Bryophytes:
-Life cycle is restricted to moist habitats because of a lack of cuticle and roots, and water
required for gamete transfer.!
-Adapted to land but only in wet or seasonally wet environments!
"!
"Lichens: associated with bryophytes (often in harsh environments), where there is no
way to sexually reproduce both symbionts at the same time!
A symbiotic relationship with!
-Fungal mycelium: hyphae, rep. disc, injected historia; soredia (packed for environment),
producing unique compounds!
-Algal cells:!
-Can break down rock and are important first colonizers and soil builders!
Ex: Thalloid (crustose) lichen to rock/foliose to leafy/fructose to reindeer moss, fungi is high in
protein!
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