The Collaborative International Dictionary of English v.0.48:
Richweed \Rich"weed`\, n. (Bot.) An herb (Pilea pumila) of the Nettle family, having a smooth, juicy, pellucid stem; -- called also clearweed. [1913 Webster]WordNet (r) 3.0 (2006):
clearweed n 1: a plants of the genus Pilea having drooping green flower clusters and smooth translucent stems and leaves [syn: richweed, clearweed, dead nettle, Pilea pumilla]