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Cycads / ˈ s aɪ k æ d z / are seed plants that typically have a stout and woody trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall.
The gymnosperms (/ ˈ dʒ ɪ m n ə ˌ s p ɜːr m z,-n oʊ-/ ⓘ nə-spurmz, -noh-; lit. ' revealed seeds ') are a group of woody, perennial seed-producing plants, typically lacking the protective outer covering which surrounds the seeds in flowering plants, that include conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae [2] The term gymnosperm comes from the ...
The spermatophytes were traditionally divided into angiosperms, or flowering plants, and gymnosperms, which includes the gnetophytes, cycads, [5] ginkgo, and conifers. Older morphological studies believed in a close relationship between the gnetophytes and the angiosperms, [ 6 ] in particular based on vessel elements .
In ferns and seed plants (including cycads, conifers, flowering plants, etc.) the sporophyte is the dominant generation; the obvious visible plant, whether a small herb or a large tree, is the sporophyte, and the gametophyte is very small. In bryophytes and ferns, the gametophytes are independent, free-living plants, while in seed plants, each ...
The motile, free-swimming sperm of bryophytes and pteridophytes, cycads and Ginkgo are the only cells of land plants to have flagella [13] similar to those in animal cells. [14] [15] The conifers and flowering plants do not have motile sperm and lack both flagella and centrioles. [16]
All that can be said at present is that they were spermatophytes. It is also highly unlikely that they were close relatives of acrogymnosperms, cycads or ginkgos, because these lineages were already established and distinct in the Late Permian. [5] Vegetative leaves of Emplectopteris were at one time included in this group.
While there are more than 200 species of cycads, only one is native to Florida, and only a couple are popular landscaping plants in our area.
The progymnosperms are an extinct group of woody, spore-bearing plants that is presumed to have evolved from the trimerophytes, and eventually gave rise to the spermatophytes, ancestral to both gymnosperms and angiosperms (flowering plants). [1]