わが国の各地をはじめ、朝鮮半島や中国に分布しています。林の中や竹薮などに生え、わが国の「らん」のなかでは最も大きな花を咲かせます。和名は、花の唇弁を一ノ谷の合戦で武勇を馳せた熊谷二郎直実が背負った母衣(ほろ)に見立ててつけられました。葉は2枚が対生し、団扇状でひだがあります。4月から5月ごろ、淡白色の地に紅紫色の斑点と筋が入る花を咲かせます。中国語では「扇脉杓蘭(shan mai shao lan)」と呼ばれます。
ラン科アツモリソウ属の常緑多年草で、学名は Cypripedium japonicum。英名は Japanese lady's slipper。
The Japanese lady's slipper (Cypripedium japonicum) belongs to Orchidaceae (the Orchid family). It is an evergreen perennial herb that is distributed throughout Japan, as well as the Korean peninsula nad China. This herb grows in woodlands or bamboo groves and blooms a largest flower in Japanese orchids. The Japanese name was given to the flower because the labellum of the flower resembles the "horo" (canipy) carried by Kumagai Jiro Naozane, who distinguished himself in the battle of Ichinotani (Ichinotani Valley). It has two opposite, fan-shaped leaves with folds, and blooms from April to May with reddish-purple spots and streaks on a light-white background. It is called "扇脉杓蘭" (shan mai shao lan) in Chinese.