n. pl. [ NL., fr. Melanconium, name of the typical genus, fr. Gr. me`las black + &unr_; dust, in allusion to the dark spores. ] (Bot.) The smallest of the three orders of Fungi Imperfecti, including those with no asci nor pycnidia, but as a rule having the spores in cavities without special walls. They cause many of the plant diseases known as anthracnose. [ Webster 1913 Suppl. ]