Cassia nictitans L.
Family - Fabaceae
Stems - From a taproot, widely branching above the base, herbaceous but stout at the base, erect to ascending, to +/-50cm tall, antrorse pubescent.
Leaves - Alternate, stipulate, even-pinnate, with +/-11 pairs of leaflets. Stipules erect, appressed, lanceolate, striate-nerved, to 6mm long, green but often with a reddish apex, antrorse strigose (at least on the margins). Gland of the petiole stalkless, to about .6mm in diameter, purplish. Petiole and rachis antrorse pubescent. Leaflets sessile, opposite, entire, to 1.4cm long, 4mm broad, linear-oblong, oblique at the base, rounded and mucronate at the apex, with antrorse strigose margins, glabrous and deep green adaxially, light green and glabrous abaxially, lateral veins evident abaxially.
Stipule and gland.
Inflorescence - Fascicles of 4-5 flowers from the side of the stem (within the internode). Each flower subtended by a linear-lanceolate bract. Bracts exceeding the pedicel. Pedicels short, to 1.2mm long.
Flowers - Petals 5, yellow, unequal, glabrous, distinct. Lowest petal enlarged, to -9mm long, 7-8mm broad, rotund. Upper petals smaller than the lowest, cupped around the other floral organs, at least one of the lateral petals with erose margins. Stamens 5, distinct, glabrous. Filaments whitish, short (to 1.2mm long). Anthers purplish to reddish, apically dehiscent, 2.5mm long. Ovary green, superior, 3mm long, densely appressed pubescent. Style up-curved, -2mm long, greenish, glabrous. Calyx deeply 5-lobed, the tube sparse pubescent, green, -1mm long. Lobes spreading, yellowish, linear-lanceolate, entire, sparse antrorse pubescent externally, glabrous internally, +/-5mm long, 1.2mm broad, often folded slightly.
Flowering - July - September.
Habitat - Slopes, ridges, open woods, prairies, thickets, roadsides, railroads. Usually on acid soils.
Origin - Native to U.S.
Other info. - This little species can be found mainly in the southern 1/2 of Missouri. The plant is easy to ID in the field because of its small yellow flowers and finely pinnate leaves. The leaves are sensitive to the touch and will close when touched or when hit by strong sunlight. This action, however, is not nearly as quick or dramatic as it is in other species from the family.
Photographs taken in Brown Summit, NC., 9-8-02.