This is a rather poorly known species, interpreted by Isely (1998) and other recent authors as centered in the lower Mississippi Valley, but especially distinct in the Ozarks. It usually occurs on less intensely flooded sites than fruticosa, often drier, sandier or rockier. This interpretation includes A. cyanostachya M.A. Curtis; but see Sm for a more divisive treatment. A. nitens is easily confused with fruticosa or croceolanata and often overlooked; see W and citations. Plants of nitens tend to become darker to blackish when dried (versus greenish to brownish in other members of the fruticosa group). Leaflets are usually more glossy above when fresh, spreading hairy to glabrate, often less clearly glandular below, and usually less mucronate; also, they tend to be relatively large and broad (L/W ca. 2-2.5), with mostly 9-17 per leaf (versus 11-23 in most fruticosa). Fruits are usually glabrous, and have been described as "dotless or essentially so" (F) but they can often be distinctly dotted with relatively small glands. The largely southern Appalachian species, A. glabra Poiret, is uncomfortably close to nitens but usually with distinctive, short to obsolete calyx lobes; its leaflets are less blackening, more retuse and less mucronate. Some plants in c. Tenn. may appear transitional from nitens to glabra (Ch, PL; D. Estes, pers. comm.).