Wufanzi, formerly known as Nanzhu, is also known as sand lotus seed, black rice leaf, black rice tree, rice tree, and black rice fruit. It is the fruit of the black rice tree. It is ripe in autumn and has a sweet taste.

Wufanzi is mainly distributed in Zhejiang, Fujian, Jiangsu, Anhui, Jiangxi, Hunan, Hubei, Guangdong, Taiwan and other places. It turns purple-black when mature, and is usually pubescent and sparsely hairy on the outside. The flowering period is generally June to July, and the fruiting period is generally August to October. In rural areas, the black rice tree is a small evergreen shrub with many branches and dense black leaves, like countless phoenix eyes.

Black rice seeds are not bitter and slightly sour when green. It usually takes until late autumn and early winter for the black rice seeds to be fully cooked. Especially after being beaten with frost, the black rice seeds are as black and round as big as peas, which is very attractive. At this time, the black rice zi is juicy, plump and has a sweet taste. According to traditional Chinese medicine, black rice seeds are sweet, sour and warm in nature. Soothe the nerves; relieve cough. Indications: palpitations, restless nights, and chronic cough.