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Parnassiaceae Gray are a family of Flowering plants 〔Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. ''Flowering Plant Families of the World''. Firefly Books: Ontario, Canada. (2007).〕 in the eudicot order Celastrales. It is not recognized in the APG III system of plant classification.〔Angiosperm Phylogeny Group. 2009. "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". ''Botanical Journal of the Linnean Society'' 161(2):105-121. (see ''External links'' below).〕 When that system was published in 2009, Parnassiaceae were treated as a segregate of an expanded Celastraceae.〔Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website. In: Missouri Botanical Garden Website. (see external links below)〕 Parnassiaceae have only two genera, ''Lepuropetalon'' and ''Parnassia''.〔Mark P. Simmons "Parnassiaceae" In: Klaus Kubitzki (ed.). ''The Families and Genera of Vascular Plants'' vol. VI. Springer-Verlag: Berlin,Heidelberg (2004).〕 ''Lepuropetalon'' has only one species, ''Lepuropetalon spathulatum'', a winter annual that usually prefers sandy soil. It is one of the smallest of flowering plants, up to 2 cm tall.〔Stephen A. Spongberg (1972). "Parnassioideae" pages 458-466 In: "The genera of Saxifragaceae in the southeastern United States" ''Journal of the Arnold Arboretum'' 53(4):409-498.〕 ''Lepuropetalon'' has a disjunct distribution, being known from the southeastern United States and central Chile,〔Adolf Engler (1930). "Saxifragaceae" In: Adolf Engler and Karl Prantl (eds.). ''Die Naturlichen Pflanzenfamilien, edition 2'' vol.18a:178-182.〕 but is probably far more common than has been reported.〔Daniel B. Ward and Angus K. Gholson (1987). "The hidden abundance of ''Lepuropetalon spathulatum''(Saxifragaceae) and its first recorded occurrence in Florida". ''Castanea'' 52(1):59-67.〕 ''Parnassia'' is a genus of perennial herbs, up to 60 cm tall, that grow in bogs, marshes, and other wet areas, mostly in cool to cold climates of the north temperate zone. There are at least 70 species.〔Ding Wu, Hong Wang, De-Zhu Li, and Steven Blackmore (2005). "Pollen Morphology of Parnassia L. (Parnassiaceae) and Its Systematic Implications". ''Journal of Integrative Plant Biology'' 47(1):2-12. (see external links below).〕 Sixty-three species occur in China and 49 of these occur nowhere else.〔Gu Cuizhi and Ulla-Maj Hultgård (2001). "Parnassia" In: Wu Zheng-yi and Peter H. Raven. ''Flora of China'' vol.8:358-379. Science Press: Beijing. Missouri Botanical Garden Press: St. Louis, MO, USA.〕 A second area of diversity for ''Parnassia'' is North America and about 9 species occur there.〔USDA Plants Database (see external links below)〕 ''Parnassia palustris'' is the most well known and widely distributed species. It ranges through most of northern Eurasia, Canada, and the western United States.〔Raymond B. Phillips (1982). "Systematics of Parnassia (Parnassiaceae): Generic overview and revision of North American taxa". Ph.D thesis. University of California at Berkeley.〕 ''Parnassia palustris'' is widely cultivated. About 10 species are known in cultivation, all as ornamentals.〔Anthony Huxley, Mark Griffiths, and Margot Levy (1992). ''The New Royal Horticultural Society Dictionary of Gardening''. The Macmillan Press,Limited: London. The Stockton Press: New York.〕 ==Description== Parnassiaceae are rhizomatous perennial herbs (''Parnassia'') or winter annuals without a rhizome (''Lepuropetalon''). The youngest part of the stem has three collateral vascular bundles. On the stems, leaves, and flowers, the epidermis has sacs filled with tannin. The leaves are alternate or subopposite, without stipules, and the margins are entire. The leaf blade is wide compared to its length and the secondary venation is subpalmate. In ''Parnassia'', the leaves are crowded into a basal rosette with a few cauline leaves above. The leaves are all cauline in ''Lepuropetalon''. In both genera, the lower cauline leaves are pseudosessile,〔 which means that the petioles are adnate to the stems. The upper cauline leaves, if present, are truly sessile. The inflorescence consists of one, or rarely two, flowers that face upward and are at the end of a peduncle that has few or no leaves. The flowers are perfect and slightly zygomorphic.〔 The five sepals are shortly connate at their bases,〔 and persistent through maturity of the fruit. The petals are either absent, or five and free from each other. In ''Parnassia'', the petals are showy and white or cream, with conspicuous veins that are usually green or gray. The margins are entire, toothed, or fimbriate. In ''Lepuropetalon'', the petals are rudimentary or absent. In both genera, the five stamens are free from each other. They are placed opposite the sepals and therefore alternate with the petals. The anthers open in sequence above the gynoecium (see next section). The five staminodes are free and placed opposite the petals. They mature after the stamens.〔 Each consists of a nectariferous pad with filamentous rays arising from its edge. Each ray is terminated by a large globular gland. The ovary is superior or half inferior and consists of 3 or 4, rarely 5, fused carpels. The walls of the carpels are incomplete so that the ovary is unilocular in its upper part.〔 The placentation is parietal.〔 The ovules are attached to T-shaped placentas in ''Parnassia'', and directly to the ovary wall in ''Lepuropetalon''. The style is absent or very short. The stigmas are decurrent along the commissures of the ovary and sometimes extended above, to form false styles called stylodia. The stigmatic areas are dry. The megagametophyte is of the ''Polygonum'' type. The fruit is an erect, membranous capsule, which opens at the apex only. The seeds are small, light, and numerous. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Parnassiaceae」の詳細全文を読む スポンサード リンク
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