(Greek, rattle,'castanct,- from the rattling of the seeds in the pod). RATTLE-BOX. A \'\-r_v large, tropical genus, of which the most interesting species is 0. retusa, a hardy, yellow-fid. annual, which has been compared to a dwarf sweet pea. For best results, the seed should be started early indoors, after being soaked in warm water. The name is commonly misspelled Crotolaria. Greenhouse kinds are subject to red spider. O.jmwaa, yields the Sunn hemp of India.