 The phenanthrenes 2,5-dihydroxy-3,4-dimethoxyphenanthrene, 9,10-dihydro-2,5-dihydroxy-3,4-dimethoxyphenanthrene, 2,7-dihydroxy-3,4-dimethoxyphenanthrene (nudol), 9,10-dihydro-2,7-dihydroxy-3,4-dimethoxyphenanthrene, 2,5-dihydroxy-3,4,9-trimethoxyphenanthrene and 2,7-dihydroxy-3,4,9-trimethoxyphenanthrene can be isolated from "Maxillaria densa".Cirrhopetalanthrin is a dimeric phenanthrene derivative from "Cirrhopetalum maculosum".Five phenanthrene glycosides, denneanoside A, B, C, D and E and one 9,10-dihydrophenanthrene glycoside, denneanoside F, can be isolated from the stem of "Dendrobium denneanum".