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The gymnosperms ( / ˈdʒɪmnəˌspɜːrmz, - noʊ -/ ⓘ JIM-nə-spurmz, -noh-; lit. 'revealed seeds') are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος ( γυμνός, gymnos ...
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta ( / pɪˈnɒfɪtə, ˈpaɪnoʊfaɪtə / ), also known as Coniferophyta ( / ˌkɒnɪfəˈrɒfɪtə, - oʊfaɪtə /) or Coniferae. The division contains a single extant class, Pinopsida.
Microphylls and megaphylls. In plant anatomy and evolution a microphyll (or lycophyll) is a type of plant leaf with one single, unbranched leaf vein. [1] Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. In the classical concept of a microphyll, the leaf vein emerges from the protostele without ...
Sporophyll. The sporophyll of a fern. It is a fertile leaf bearing reproductive structures. A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls (whether they are microphylls or megaphylls) bear either megasporangia and thus are called megasporophylls, or ...
Sporophyte. Diagram showing the alternation of generations between a diploid sporophyte (bottom) and a haploid gametophyte (top) A sporophyte ( / ˈspɔːr.əˌfaɪt /) is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Cotyledon from a Judas-tree (Cercis siliquastrum, a dicot) seedling Comparison of a monocot and dicot sprouting. The visible part of the monocot plant (left) is actually the first true leaf produced from the meristem; the cotyledon itself remains within the seed Schematic of epigeal vs hypogeal germination Peanut seeds split in half, showing the embryos with cotyledons and primordial root Two ...
Gnetum is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been proposed to have been the first plants to be insect- pollinated as their fossils occur in association ...
Cycads / ˈsaɪkædz / are seed plants that typically have a stout and woody ( ligneous) 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.