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Unformatted text preview: Ginkgo ), Coniferophyta (conifers), and Gnetophyta (gnetophytes) Ovules and seeds exposed and not covered by sporophyte tissue at time of pollination; wood lacks fibers and contains only tracheids (except in gnetophytes, which have vessels in addition); some have flagellated sperm carried in a pollen tube toovule; female gametophyte produces several archegonia and embryos, but usually only one embryo survives/ovule Seed plants probably evolved from seed-bearing progymno-sperms sometime during the Devonian (370 million years ago); current gymnosperms represent a series of separate lineages Trees and shrubs with no herbaceous representatives (some vine-like Gnetum species are present); distributed world-wide from boreal conifer forests to tropics, some taxa mixed with Angiosperm trees, others in pure stands of Gymnosperms...
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This note was uploaded on 11/14/2011 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.
- Fall '08