1811, in botany, from homogamy + -ous. Greek homogamos meant "married to the same wife; having married sisters."
Entries linking to homogamous
homogamy n.
1805, "condition of bearing flowers that do not differ sexually," from homo- (1) "same" + -gamy.
-ous
word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."