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Pereskia
''Pereskia'', as traditionally circumscribed, is a genus of 17 tropical species and varieties of cacti that do not look much like other types of cacti, having substantial leaves and thin stems. They originate from the region between Brazil and Mexico. Members of this genus are usually referred to as lemon vines, rose cacti or leaf cacti, though the latter also refers to the genus ''Epiphyllum''. The genus is named after Nicolas-Claude Fabri de Peiresc, a 16th-century French botanist.
Species of ''Pereskia'' generally resemble other types of plants, such as roses. ''Pereskia'' species have large, bright green, privet-like leaves and long spiny stems. Not always succulent plants, they can be classified as shrubs, climbing plants or slightly succulent trees. However, close examination shows spines developing from areoles, and the distinctive floral cup of the cactus family. Unlike ''Pereskiopsis'', ''Maihuenia, Quiabentia'' and ''Austrocylindropuntia'' which have persistent succulent leaves, ''Pereskia'' is the only cactus genus that has persistent non-succulent leaves. It is believed that the ancestor of all cacti resembled ''Pereskia''.
Molecular phylogenetic studies have shown that species traditionally assigned to ''Pereskia'' fall into two clades, so that the genus is paraphyletic (i.e. it does not comprise all the descendants of a common ancestor). In 2013, it was suggested that eight species be moved to the genus ''Leuenbergeria'', with the other nine species remaining in ''Pereskia''.
==Description==
Plants leafy and spiny, treelike, shrubby, and often scrambling. Majority species may be treelike or shrubby, 2 – 7 m high, highest at 10 m. ''Pereskia aculeata'' forms clambering shrubs or climbing vines 3 – 10 m long. Roots sometimes thickened and tuberous. Leaves alternate, broad, flattened, deciduous, usually with petioles, 2 – 20 cm long. Areoles in the axils of the leaves, usually with wool, bearing spines and leaves. Spines 0 – 8 on young primary areolas on twigs, to numerous on trunk (15 - 40, max. 120), unequal in length 2 – 12 cm, straigh, usually black. Flowers solitary or in an inflorescences of 2 - 15 flowers (''P. aceulata'' 70, ''P. grandiflora'' 10 – 30), 2 – 8 cm in diameter, usually pink, rose, purple, sometimes orange, yellow, white, cream. Fruits solitary or clustered, variable in shape, oblonge, pear shaped, usually green or yellowgreen in maturity, also orange, reddish, brownish, 2 - 7, max. 10 cm long. Three species have fruits very small, 0,5 – 1,5 cm globbose, glossy black. Seeds 2 – 7 mm large, obovate to kidney shaped, glossy black.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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