Publication: Mem. Torrey Bot. Club. 5: 173 1894.
selected vouchers: WTU
Notes: Here we follow the treatment in FNA that recognizes two subspecies - incisa and paysonii, the latter of which is out of our area. FNA authors describe D. incisa as being highly variable in almost all features, likely the result of hybridization with other members of the genus with which it shares a common range.