FABACEAE: Legume Family
KEY TO SPECIES OF AMORPHA
1. Shrubs usually less than 1 m; leaves with petiole chiefly shorter than width of lowest leaflet ............. 2
2. End of midvein of leaflets swollen and sometimes extending beyond blade ................................................. A. herbacea
2. End of midvein of leaflets extending beyond blade as a slender very short tapered tip …................................ A. canescens
1. Shrubs usually more than (1)1.2 m; leaves with most petioles longer than width of lowest leaflets ................................... 3
3. Calyx lobes poorly developed, all less than 0.8 mm and never narrowly acute .................................................... A. glabra
3. Calyx lobes, or at least some, well-developed and longer than 0.8 mm, some narrowly acute or acuminate ........................4
4. Calyx lobes from half as long to longer than calyx tube, all acute or acuminate, lateral lobes more than 1 mm ..........................5
5. Leaflets with lateral veins mostly 5-6(7) pairs, branches of the larger veins never conspicuous on blade underside; lower calyx lobes (1.8)2.5-3.5 mm ............................................................................................................. A. schwerinii
5. Leaflets with lateral veins ca (9)10-12(14) pairs; midvein and branches of the larger veins prominently raised on underside thus forming a conspicuous vein system; lower calyx lobes (1.2)1.5-2 mm ................................ A. paniculata
4. Calyx lobes, or at least some, less than 1/2 length of calyx tube, at least some of upper lobes usually rounded, lateral lobes less than 1 mm ............ 6
6. Summit of stipules with a dense tuft of long tannish curly hairs; foliage, sepals, and pedicels blackening or at least darkening upon drying; calyx tube without glands or with sparse very small slightly elevated glands ............................................ A. nitens
6. Summit of stipules lacking such a tuft of hairs; foliage, sepals, and pedicels never blackening and rarely even darkening upon drying; calyx tube usually glandular with often conspicuous elevated glands ....................................................7
7. Plants to ca 1.2 m; leaflets 1.4-2(2.4) times as long as wide; standard ca 4.5-6 mm across; filament 8-10 mm. Plants of southeastern Oklahoma and eastern Arkansas ..................................................................................... A. ouachitensis
7. Plants to (1)2-3(4) m; leaflets mostly 2-3(6) times as long as wide; standard ca 3.5-4.2 mm across; filament 6-8 mm. Plants of all states from Texas into North Dakato, East except Maine, and some states to the west ....................................... A fruticosa