Amorpha canescens Pursh
CC = 8
CW = 5
MOC = 77
Family - Fabaceae/Faboideae
Habit - Small shrubs or subshrubs, from a knotty rootstock with a deep thick taproot.
Stems - To 1m tall, ascending to erect, woody below, multiple from base, typically simple, canescent above, sparsely pubescent to glabrescent below, striate-nerved.
Leaves - Alternate, odd-pinnately compound, stipulate. Stipules linear, purplish, deciduous, to 3 mm long. Leaves to 8 cm long, the rachis canescent. Leaflets alternate to opposite, stipellate. Stipels small, purple, thin and dry. Leaflets entire, typically linear-oblong to lanceolate-ovate, mucronate, rounded at the base, with single midrib, canescent, to 1.6 cm long, 5 mm broad. Terminal leaflet smaller than laterals, cuneate at base, truncate at apex, mucronate.
Inflorescence - Multiple terminal and axillary racemes, indeterminate, pedunculate, to 25 cm long, near stem tips. Axis of racemes canescent. Pedicels to 1 mm long.
Flowers - Calyces 5-lobed, the tube 1.5-2.0 mm long, the lobes 1.5-2.0 mm long. Corollas not papilionaceous, the single petal 4-5 mm long, 2.0-2.5 mm wide, obovate, folded around stamens and pistil, bluish purple. Stamens 10, exserted, the free portion of the filaments 4-5 mm long, the anthers 0.3-0.5 mm long, yellow. Ovary superior, 1.0-1.5 mm long, densely hairy, the style 2-3 mm long, glabrous or densely hairy. Stigma glabrous, 3-lobed, purplish.
Fruits - Modified legumes 3-4 mm long, 1.2-1.5 mm wide, slightly flattened, exserted beyond the persistent calyx tube, hairy and gland-dotted, 1-seeded. Seeds 2.0-2.4 mm long, 1.0-1.4 mm wide, olive to reddish brown.
Flowering - May - August.
Habitat - Upland prairies, glades, forest openings, bluffs, roadsides. Also cultivated.
Origin - Native to U.S.
Other info. - This species of Amorpha is easily recognized when flowering by its dense canescence (conspicuous gray hairiness). Non-flowering specimens can appear similar to another legume, Tephrosia virginiana (goat's rue). The two can be reliable distinguished by the shape of the leaflet bases: in A. canescens these are rounded or slightly cordate, whereas in T. virginiana they are tapered. The presence or absence of a mucro (minute spiny tip) on the leaflets is less reliable.
Photographs taken at Lichen Glade, St. Clair County, MO., 6-16-05 and at Indigo Prairie Conservation Area, Dade County, MO., 6-18-05 (DETenaglia); also at St. Joe State Park, St. Francois County, MO, 5-14-2012, and Little Lost Creek Conservation Area, Warren County, MO, 6-9-2017 (SRTurner).