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In botany, a whorl is an arrangement of sepals, petals, leaves, stipules or branches that radiate from a single point and surround or wrap around the stem.〔(【引用サイトリンク】title=whorl )〕〔Lindley, John. ''(A Glossary of Technical Terms Used in Botany )'', p.100, Bradbury and Evans, London, 1848.〕 A whorl consists of at least three elements; a pair of opposite leaves is not called a whorl. The morphology of most Angiosperm flowers is based on four whorls: #the calyx, a whorl of sepals at the base, above which are #the corolla, a whorl of petals, #the androecium, a whorl of stamens (each comprising a filament and an anther), and #the gynoecium, a whorl of the female parts of a flower: the stigma, style and ovary. A flower lacking any of these floral structures is said to be ''incomplete'' or ''imperfect''. Not all flowers consist of whorls since the parts may instead be spirally arranged, as in Magnoliaceae. For leaves to grow in whorls is fairly unusual except in plant species with very short internodes. It does however occur in some trees such as ''Brabejum stellatifolium'' and other Proteaceae, such as some ''Banksia'' species. In examples such as those illustrated, crowded internodes within the whorls alternate with long internodes between the whorls. ==See also== * Phyllotaxis 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「Whorl (botany)」の詳細全文を読む スポンサード リンク
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