Pittonia4: 211. 1900
sw United States.
A peculiar desert xerophyte with subsessile, erect capsules, and unique petal glands, Carsonia is segregated from Peritoma by its unique cytology (2n = 32). Whether it is autochthonously specialized or actually related to, and derived from, some Old World ancestors, such as the Central Asiatic-Near Eastern Cleome sect. Thylacophora Franch, the dozen or so species of which, probably through convergence, also bear epipetaloid glands, remains to be determined.