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。山野にふつうに生え、高さは2メートルほどになります。「たらのき」の仲間ですが、樹木ではなく多年草です。2回羽状複葉で細かい毛があり、縁には鋸歯があります。8月から9月ごろ、球状花序に小さな淡緑色の花を咲かせます。よくスーパーで見かける「白うど」は、籾わらや落ち葉などをかけ、暗所で栽培したものです。台湾華語では「食用土當歸」、中国語では「食用土当帰(shi yong tu dang gui)」と呼ばれます。
ウコギ科タラノキ属の多年草で、学名は Aralia cordata。英名は Udo。
The Udo (Aralia cordata) belongs to Araliaceae (the Ginseng family). It is a perennial herb that is distributed throughout Japan, as well as the Korean Peninsula and China. This herb grows commonly in mountains and fields, and can reach about 2 m in height. It is related to the Hercules club (Aralia elata), though it is not a woody plant. The leaves are bipinnate compound with fine hairs and serrated edges. The small pale green flowers bloom in the spherical clusters from August to September. The white udo is a dark-grown cultivated crop. It is called "食用土當歸" (shi yong tu dang gui) in Taiwanese Chinese and "食用土当帰" (shi yong tu dang gui) in Chinese.