Unformatted text preview: As vascular plants become even more complex, sperm are retained in the male gametophyte, the pollen grain, freeing sexual reproduction from water dependence. • In the seed plants, the seed (embryo sporophyte surrounded by nutrients and seed coat) replaces the haploid single-celled spore as the dispersal unit, providing the next generation with a "head start" on survival. These adaptations to the terrestrial environment have made vascular plants the predominant vegetation in most parts of the world. While abundant, Bryophytes are rarely predominant. To summarize, vascular plants have: • Body plan along a supporting axis (the stem) • Vascular tissue o Xylem promotes (allows) increase in size • Sporophyte generation independent and assimilative o Gametophyte often dependent on the sporophyte • Cutin and/or suberin produced on aerial parts to minimize dehydration • Generally large surface area/volume ratio o Allows land survival with less surface H 2 O...
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- Fall '09
- Bryophytes, Fern, vascular tissue, Plant Kingdom