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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 ...
Gymnosperms are divided into 12 families of trees, shrubs and woody vines. [5] Sequoiadendron giganteum , the giant redwood, is the largest tree in the world, and Sequoia sempervirens , the coastal redwood, is the tallest. [ 6 ]
Like other species of Cladophora, C. callicoma has flagellated gametes which are identical in appearance and ability to move. [20] Gametes of two distinct sizes (anisogamy). Both of similar motility. Species of Ulva, the sea lettuce, have gametes which all have two flagella and so are motile. However they are of two sizes: larger 'female ...
Conifers are the largest and economically most important component group of gymnosperms, but nevertheless they comprise only one of the four groups. The division Pinophyta consists of just one class, Pinopsida, which includes both living and fossil taxa. Subdivision of the living conifers into two or more orders has been proposed from time to time.
Early land plants had sporophytes that produced identical spores (isosporous or homosporous) but the ancestors of the gymnosperms evolved complex heterosporous life cycles in which the spores producing male and female gametophytes were of different sizes, the female megaspores tending to be larger, and fewer in number, than the male microspores ...
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Gnetophyta (/ n ɛ ˈ t ɒ f ɪ t ə, ˈ n ɛ t oʊ f aɪ t ə /) is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three relict genera: Gnetum (family Gnetaceae), Welwitschia (family Welwitschiaceae), and Ephedra (family ...
This social parasite is native to 15 states across the U.S. and obliges other bee species to raise its offspring. However, Suckley’s cuckoo bumble bees A New Law Protects Two Beloved Species ...