Monographs Details: Cassia fasciculata var. rostrata (Wooton & Standl.) B.L.Turner
Authority: Isley, Duane. 1975. Leguminosae of the United States: II. Subfamily Caesalpinioideae. Mem. New York Bot. Gard. 25 (2): 1-228.
Description:Distribution and Ecology - W extremity of species as defined in key. S: red-sandy xeric areas. May-July or continuing to end of season granted rainfall. N: deep-sands or sandy-clay, dunes, blowouts often in sand along river margins, less frequently open range, dry prairie or disturbed areas. June-July(-Sept.).

Discussion:Chamaecrista rostrata Woot. 8c Standi. (1913) Cassia fisheri Cory (1936) Cassia rostrata (Woot. 8c Standi.) Tidestr. (1941) Pullen (1963) regards var. rostrata as the most distinct varietal aspect of C. fasciculata. On the other hand, neither Waterfall (1969) nor Barkley (1968) mentions it for their respective states, Oklahoma and Kansas. I am inclined to view it not as a congruent variety but rather several semi-xeric distinct to ambiguous peripheral phases of the species. Some of these are apparently local or rare; total collections are few, and there are discontinuities in the distribution. One group is in southern Texas, a triangle roughly bordered by Atascosa, Maverick and Webb. cos. where, locally abundant in xeric sands, plants possess characters attributed to var. rostrata by Texas authors: narrow pods (mostly 3-3.5 cm wide), smaller flowers, few leaflets, small glands. Except for growth habit, most characters of these populations are those of the contiguous variant 1 of var. puberula to which they are probably most closely related. Support for the biological reality of at least this phase of var. rostrata is provided by Howard Irwin who states that it will not easily cross with typical C. fasciculata. Sporadic collections from central-western Texas are placed with var. rostrata (Map 38), but some scarcely differ perceptibly from var. fasciculata. Disjunct from these, var. rostrata, as originally characterized, turns up along the eastern margin of the Texas Panhandle (Hemphill, Roberts, Wheeler, Hall cos.) and north to southwestern Kansas. These phenotypes have the small gland and reduced leaflet number attributed to var. rostrata, but a frequently rostrate legume essentially as broad (5 mm) as typical var. fasciculata. Chamaecrista rostrata was described from Quay co., New Mexico (Wooton and Standley, 1913), and reiterated in the Flora of New Mexico (Wooton and Standley, 1915). Simultaneously they reported Chamaecrista fasciculata from the Organ Mts. in New Mexico. But there is no C. fasciculata from New Mexico at NMC, and I have seen no collections from the Texas Panhandle west of Roberts and Hall cos. (Map 38). Possibly rare or relictual populations have been wiped out by agriculture.