Last Addition: November 25, 2006.
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Calycadenia micrantha occurs mostly in small colonies in the vicinity of Clear Lake, Lake Co., California. A few additional populations occur in Trinity and Monterey Cos., California. Like C. hooveri, C. micrantha is exceptional in being self-compatible; all other species of Calycadenia are strongly self-incompatible. Calycadenia micrantha is found in very barren substrates at sites ranging from about 500-1500 meters in elevation. Calycadenia micrantha is a self-compatible, diminutive derivative of the more robust widespread species, C. truncata, and differs from that species primarily in the reduction of structures correlated with the shift in breeding habit, e.g., ligule length (<3.5 mm vs mostly 5-12 mm), and disk floret number (1-3 vs mostly 5-25). The chromosome number of C. micrantha is n = 7. Calycadenia micrantha readily hybridizes with C. truncata in vitro but viable hybrid fruits are formed only on C. micrantha parents.