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Ginkgoaceae Engler
Common names:Ginkgo, maidenhair tree, [Chinese].
Taxonomic notes:The ginkgo is monotypic; this treatment presents sundry information for the Class Ginkgoopsida, Order Ginkgoales, Family Ginkgoaceae, and Genus Ginkgo. For the species, go to Ginkgo biloba.Description:Deciduous, dioecious trees. Bark gray, furrowed, with flattened ridges. Long shoots and short (spur) shoots present. Roots fibrous to woody. Leaves simple, flattened, fan-shaped, alternate to fascicled, stomata ventral, apex deeply cleft to truncate; petioles equal to or exceeding blades; resin canals absent; with numerous parallel veins; epidermis usually without exothecium. Pollen cones borne on spurs, elongate, catkin-like; sporophylls distributed along axis; bracts absent; pollen spheric. Seed cones absent; ovules 2, borne on spurs, pedunculate, subtended by collar believed to comprise 2 modified megasporophylls, orange-yellow, fleshy, pulpy, maturing in one year. Seeds with fleshy outer coat, inner coat hard, thin-shelled, wingless; cotyledons 2-3 (1, 2).Range:Native to China, but widely cultivated; see below for details.Remarks:Ginkgo differs from all other seed plants except Cycadales in having a distinct mode of fertilization by motile or free swimming sperm. Fertilization is usually by wind pollination (2).Ginkgo is often referred to as a 'living fossil' because nearly identical plants are known from fossils nearly 200 million years old (1). The fossil record shows that they were formerly a widespread, abundant and diverse group. Citations:(1) R. David Whetstone in Flora of North America online.(2) Silba 1986. See also: A.H. Franklin. 1959. Ginkgo biloba L.: Historical summary and bibliography. Virginia Journal of Science, n. s. 10:131-176. J. Jalalpour, M. Malkin, P. Poon, L. Rehrmann and J. Yu. 1997. Introduction to the Ginkgoales. Web page hosted by the Museum of Paleontology at the University of California, Berkeley. URL= http://www.ucmp.berkeley.edu/seedplants/ginkgoales/ginkgo.html, accessed 29-Jun-1999. C.N. Page. 1990. Coniferophytina: Ginkgoaceae. In: K. Kubitzki et al., eds. 1990+. The Families and Genera of Vascular Plants. 1+ vol. Berlin etc. Vol. 1, pp. 284-289. |
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This page is from the Gymnosperm Database
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