Perianth - Kahi

The outermost component of an angiosperm flower. It is not directly related to reproduction, but rather serves to protect the pistil and stamen inside and to attract insects to transmit pollen. The degree of development and differentiation of the perianth varies depending on the plant group. Perianth-less anemone flowers are seen in the Cranberry family, Houttuynia family, and Salicaceae family, and some see them as primitive, while others see them as a secondary degeneration. In general, wind-pollinated flowers have poorly developed perianths. Simple perianth flowers, which have a single perianth, are considered primitive, and include those with poorly developed perianths such as those in the Fagaceae and Juglandaceae families, and those with well-developed petal-like perianths such as those in the Anemone genus of the Ranunculaceae family. In double perianth flowers, the perianth is differentiated into two, an inner and an outer whorl. There are homoperianth flowers, such as in the Liliaceae and Iridaceae families, where there is not much difference between the outer and inner whorls, and heteroperianth flowers, which are differentiated into a calyx and a corolla. Heteroperianth flowers are the most evolved form and are found in many dicotyledonous plants. The leaves that make up the perianth are called tepals.

In the Gnetosperm class, the organs surrounding the ovules and stamens are also called perianth.

[Michio Tamura]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

被子植物の花の構成要素でもっとも外側にある部分をいう。生殖作用に直接には関係せず、内部にある雌しべ・雄しべの保護や、花粉を媒介するための昆虫誘引などの役目をもつ。花被の発達、分化の程度は植物の群によって違いがある。花被のない無花被花はセンリョウ科、ドクダミ科、ヤナギ科などにみられ、原始的とみる意見と、反対に二次的に退化したとみる意見とがある。一般に風媒花では花被の発達は悪い。花被が一重の単花被花は原始的と考えられ、ブナ科やクルミ科のように花被の発達の悪いものや、キンポウゲ科のイチリンソウ属のようによく発達して花弁状となるものなどがある。花被が内外2輪に分化した重花被花には、ユリ科、アヤメ科のように外輪・内輪にあまり大きな差のない同花被花と、萼(がく)と花冠(かかん)に分化した異花被花とがある。異花被花はもっとも進化した状態で、多くの双子葉植物にみられる。花被を構成している花葉(かよう)は花被片とよばれる。

　裸子植物のグネツム綱で、胚珠(はいしゅ)や雄しべを取り囲む器官も花被とよばれる。

［田村道夫］

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例