Plantae - Ginkgo Coniferophyta(conifers and Gnetophyta(gnetophytes Ovules and seeds exposed and not covered by sporophyte tissue at time of

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Plantae–Seedless Vascular Plants: ferns, fern allies, and horsetails. Divided into four groups: Psilotophyta (whisk ferns), Lycophyta (club mosses), Sphenopsida (horsetails), Pterophyta (ferns) Xylem and phloem present; sporophyte dominant; asexual spores produced in sporangia; some taxa homosporous, others heterosporous Earliest vascular plants were small, simple, and dominated mid-Silurian to mid-Devonian landscapes (425–370 million years ago); by late Devonian through the Carboniferous (the Coal Age), plants formed swamp forests of large trees; major groups died out by end of the Permian (250 million years ago) Most living taxa are depauperate remnants of large tree species of the Coal Age flora Plantae–Gymnosperms: conifers, cycads, gnetophytes , pines, junipers, yews, sequoia; divided into four groups: Cycadophyta (cycads), Ginkgophyta (
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

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...
View Full Document

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.

Ask a homework question - tutors are online