BIOA02H3 Lecture 11: Lecture Notes 11
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BIOA02H3 Full Course Notes
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Document Summary
No living relatives left so must rely on fossil data. Extinct genus rhynia and related genera most likely first vascular plants. Sporangia produced at the tips of photosynthetic branches. Simple stem had a central core of xylem. Rhynia, an early now extinct seedless vascular plant. Have upright or horizontal stems containing xylem and small green leaves and roots. Cone or strobulus: cluster of sporophylls (spore-bearing leaf) Second in phylum size only to flowering plants. Extremely diverse group in terms of size and habitat (wet to arid) Familiar plant body is sporophyte stage (emerging leaves look like a fiddle head) Sporangia often in sori on lower surface or margins of fronds. Antheridia and archegonia develop on underside of gametophytes. When water is present, the antheridium will burst and release helical sperm with many flagella which will swim towards a mature archegonia, drawn by a chemical that is released.
