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Gymnospermae
Thesaurus| Noun | 1. | Gymnospermae - plants having naked seeds not enclosed in an ovary; in some systems considered a class (Gymnospermae) and in others a division (Gymnospermophyta); comprises three subdivisions (or classes): Cycadophytina (class Cycadopsida) and Gnetophytina (class Gnetopsida) and Coniferophytina (class Coniferopsida); in some classifications the Coniferophytina are divided into three groups: Pinophytina (class Pinopsida) and Ginkgophytina (class Ginkgopsida) and Taxophytina (class Taxopsida)class Gymnospermae, division Gymnospermophyta, Gymnospermophytaclass - (biology) a taxonomic group containing one or more ordersdivision Spermatophyta, Spermatophyta - seed plants; comprises the Angiospermae (or Magnoliophyta) and Gymnospermae (or Gymnospermophyta); in some classification systems Spermatophyta is coordinate with Pteridophyta (spore producing plants having vascular tissue and roots) and Bryophyta (spore producing plants lacking vascular tissue and roots)gymnosperm family - a family of gymnospermsgymnosperm genus - a genus of gymnospermsgymnosperm - plants of the class Gymnospermae having seeds not enclosed in an ovaryclass Gnetopsida, Gnetophyta, Gnetophytina, Gnetopsida, subdivision Gnetophytina - gymnospermous flowering plants; supposed link between conifers and angiosperms; in some systems classified as a class (Gnetopsida) and in others as a subdivision (Gnetophytina or Gnetophyta)class Cycadopsida, Cycadophyta, Cycadophytina, Cycadopsida, subdivision Cycadophyta, subdivision Cycadophytina - palmlike gymnosperms: includes the surviving order Cycadales and several extinct orders; possibly not a natural group; in some systems considered a class (Cycadopsida) and in others a subdivision (Cycadophytina or Cycadophyta)class Pteridospermopsida, Pteridospermopsida - extinct gymnosperms most of Carboniferous to Jurassic: seed ferns and alliesclass Coniferopsida, Coniferophyta, Coniferophytina, Coniferopsida, subdivision Coniferophytina - cone-bearing gymnosperms dating from the Carboniferous period; most are substantial trees; includes the classes Pinopsida (subdivision Pinophytina) and Ginkgopsida (subdivision Ginkgophytina) and Taxopsida (subdivision Taxophytina) which in turn include the surviving orders Coniferales and Taxales (yews) and sometimes Ginkgoales as well as extinct orders such as Cordaitales (of the Carboniferous and Permian)class Ginkgophytina, class Ginkgopsida, Ginkgophytina, Ginkgopsida, subdivision Ginkgophyta, subdivision Ginkgophytina - ginkgos: in some systems classified as a class and in others as a subdivision; used in some classifications for one of five subdivisions of Gymnospermophytagymnospermous tree - any tree of the division Gymnospermophyta |
Gymnospermae
Gymnospermae[‚jim·nə′spər·mē] (botany) The equivalent name for Pinophyta. Gymnospermae (Pinophyta), the most ancient class or group of seed plants, which occupy a position between the Pteridophyta and the Angiospermae (flowering plants). Gymnospermae are distinguished from Pteridophyta by the presence of ovules and from Angiospermae by the lack of carpels. (In Gymnospermae the pollen falls directly on the micropyle of the ovule.) The Gymnospermae, including all contemporary species, have strobiles. Shortened and restricted in length, these reproductive shoots bear sporophylls. Only the most ancient classes of Lyginopterides, or “seed ferns,” lack strobiles. All Gymnospermae are trees or shrubs that often reach gigantic size, as in some conifers. Some Gymnospermae are heavily branched and bear many small or tiny, often scaled, leaves (Cordaites, ginkgoes, and conifers), while others have few or no branches but relatively large, usually pinnate leaves (Lyginopterides, Bennettites, Cycadales, and Wel-witschia). The leaves differ greatly in number, size, and anatomical structure. Most Gymnospermae have only tracheidal water-conducting elements of the xylem. (They are ladder-like or, more often, linear.) Only the Welwitschia, Gnetum, and Ephedra have vessels. The stoma also vary, a fact that often makes it possible to determine the genera from nothing more than a leaf fragment. Like other seed plants, all Gymnospermae are heterospor-ous. Their microsporophylls and megasporophylls differ greatly in form, size, and structure. Some are large and pinnate, while others are integral and small. The conifers have megasporophylls, which, as a result of reduction and coalescence, are practically indistinguishable in the fused structure (that is, seed scales). In most of the oldest and most primitive seed ferns, strobiles did not develop, but both microsporophylls and megasporophylls were situated freely on ordinary, long shoots. In the remaining Gymnospermae the sporophylls are gathered into more or less compact strobiles. In some of the Bennettites, the strobiles are bisexual. However, in most of the species the strobiles are unisexual (dioecious)—that is, the strobiles consist either of microsporophylls (male strobiles) or megasporophylls (female strobiles) of varying structure. Gymnospermae existed during the Upper Devonian period. Representatives of most orders of Gymnospermae have been traced to the Carboniferous and Permian periods, and Gymnospermae flourished in the Mezozoic era. Today there are only about 600 species, most of which are conifers. There are about 100 species of Cycadales, about 45 species of Ephedra, and about 40 species of Gnetum. REFERENCESGolenkin, M. I. Kurs vysshikh rastenii. Moscow-Leningrad, 1937.
Takhtadzhian, A. L. Vysshie rasteniia, vol. 1. Moscow-Leningrad, 1956.
Kristhtofovich, A. N. Paleobotanika, vol. 15: Golosemennye i po-krytosemennye. Moscow, 1963.
Kozo-Polianskii, B. M. Kurs sistematiki vysshikh rastenii. Voronezh, 1965.
Chamberlain, C. J. Gymnospermus, Structure, and Evolution. Chicago, 1935.
Engler, A. Syllabus der Pflanzenfamilien, 12th ed., vol. 1. Berlin, 1954.A. L. TAKHTADZHIAN gymnophobia
gym·no·pho·bi·a (jim'nō-fō'bē-ă), Morbid dread of the sight of a naked person or of an uncovered part of the body. [G. gymnos, naked, + phobos, fear] gymnophobia Morbid fear of nudity; more commonly nudophobia.gymnophobia (jĭm-nō-fō′bē-ă) [Gr. gymnos, naked, + phobos, fear] An abnormal aversion to viewing a naked body. Gymnospermae
Related to Gymnospermae: AngiospermaeSynonyms for Gymnospermaenoun plants having naked seeds not enclosed in an ovarySynonyms- class Gymnospermae
- division Gymnospermophyta
- Gymnospermophyta
Related Words- class
- division Spermatophyta
- Spermatophyta
- gymnosperm family
- gymnosperm genus
- gymnosperm
- class Gnetopsida
- Gnetophyta
- Gnetophytina
- Gnetopsida
- subdivision Gnetophytina
- class Cycadopsida
- Cycadophyta
- Cycadophytina
- Cycadopsida
- subdivision Cycadophyta
- subdivision Cycadophytina
- class Pteridospermopsida
- Pteridospermopsida
- class Coniferopsida
- Coniferophyta
- Coniferophytina
- Coniferopsida
- subdivision Coniferophytina
- class Ginkgophytina
- class Ginkgopsida
- Ginkgophytina
- Ginkgopsida
- subdivision Ginkgophyta
- subdivision Ginkgophytina
- gymnospermous tree
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