BIOL108 Lecture Notes - Lecture 13: Lycopodiophyta, Herbaceous Plant, Gametophyte
21 Jun 2018
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BIO 108 Lecture 12 / 13
Lecture 13 – Vascular Plants
Characteristics of Extant Vascular Plants:
Vascular Tissue:
oXylem:
Contains lignin (strengthening polymer)
Dead hollow cells act as water pipes
oPhloem
Living cells
Distribute nutrients, organic products
Complex Multicellular Roots
oAbsorb nutrients, provide anchor
Complex Multicellular Leaves
oPhotosynthetic organs
Sporophylls:
oModified leaves that bear sporangia (spore-producing organ)
Sporophyte dominant life cycle
oIncreased size, complexity and persistence
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Dead hollow cells act as water pipes: phloem. Complex multicellular roots: absorb nutrients, provide anchor. Sporophylls: modified leaves that bear sporangia (spore-producing organ) Sporophyte dominant life cycle: increased size, complexity and persistence. Increased size, complexity and persistence: not continuously nutritionally dependant on gametophyte. Gametophytes: tiny independent plants on or just below soil surface. Flagellated sperm: must swim in a film of water to reach egg: similar to bryophytes, seedless vascular plants most common in relatively damp habitats, still need water to reproduce. Carboniferous period (~ 300mya): lycophytes existed as small herbaceous plants and as giant woody trees. Giant lycophytes thrived in warm, moist swamps. Became extinct when the climate became cooler and drier. Smaller lycophytes survived and are represented by about 1000 species today. Whisk ferns once considered living fossils (no roots or leaves) Lecture 12 / 13: in carboniferious horsetails grew to 15 m.
