わが国の本州から四国・九州、それに中国の中・南部やビルマに分布しています。湿り気のある林内や谷沿いの日陰に生え、高さは30〜70センチになります。果実ができないので、根茎を伸ばして広がります。葉は剣形で光沢があります。4月から5月ごろ、花茎を伸ばして、真ん中に橙色の斑がある淡い青紫色の花を咲かせます。外花披片にはとさか状の突起があり、花柱の先は分裂して花弁のように見えます。中国語では「蝴蝶花(hu die hua)」と呼ばれます。
The Crested iris (Iris japonica) belongs to Iridaceae (the Iris family). It is a perennial herb that is distributed to Honshu, Shikoku and Kyushu in Japan, as well as central-southern China and Burma. This herb grows in wet forests or shady places arong streams, and can reach 30-70 cm in height. It spreads by rootstocks, since it is sterile. The leaves are sword-shaped and glossy. The flowering stalks are borne and pale bluish-purple flowers bloom from April to May. The flower has orange mottles in the center. The outer tepals have cristate projections, and the divided style is petaloid. In Chinese, it is called "蝴蝶花" (hu die hua).