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| 1 Leaves unifoliolate (rarely with a few upper leaves trifoliolate). |
| ..2 Plant prostrate, trailing, usually with many leaves; stipels absent |
| ..2 Plants erect or ascending, usually with fewer than 6 leaves; stipels present |
| 1 Leaves trifoliolate (rarely with a few lowermost leaves unifoliolate, these generally withering before flowering and fruiting). |
| ....3 Plant erect; pubescence of the lower leaf surface not restricted to the veins (except in the rare upright forms of R. difformis keyed below). |
| ......4 Terminal leaflet suborbicular, 1.0-1.3× as long as wide; plants ascending to erect (or more usually twining [keyed elsewhere]) |
| ......4 Terminal leaflet elliptic1.6-2.5× as long as wide; plants erect. |
| ........5 Plant lavishly branched, bushy (with something of the aspect of a Baptisia); terminal leaflets 0.5-2.0 cm long; pubescence of the lower leaf surface sparse, not velvety to the touch; flowers solitary (-3) in leaf axils |
| ........5 Plant unbranched or with few well-developed branches in its upper portion; terminal leaflets (2.0-) 2.5-5 cm long; pubescence of the lower leaf surface grayish tomentose and velvety to the touch; flowers many, in racemes. |
| ..........6 Inflorescence a single exserted terminal raceme, 5-20 cm long; stipules caducous; [plants of s. SC southward] |
..........6 Inflorescences several and axillary, each 1-3 cm long (or with a short terminal inflorescence also); stipules persistent; [plants widespread in our area] |
| ....3 Plant trailing or twining; pubescence of the lower leaf surface mostly restricted to the veins. |
| ............ 7 Calyx 8-14 mm long, about as long as the corolla; [plants collectively widespread in our area]. |
| ............ ..8 Calyx 10-14 mm long; inflorescence (including peduncle) 5-25 cm at anthesis, elongating further in fruit, with flowers scattered; [MS and w, TN westward] |
| ............ ..8 Calyx 8-10 (-12) mm long; inflorescence (including peduncle) 1-2 cm long at anthesis, elongating to 4 (-8) cm, the flowers tightly packed; [collectively widespread in our area]. |
| ............ ....9 Pubescence of petiole of mostly incurved hairs 0.2-0.4 mm long; terminal leaflet 1-3 (-3.5) cm long; plants generally trailing; [of ne. FL southward] |
| ............ ....9 Pubescence of petiole of mostly spreading hairs 0.5-0.6 mm long; terminal leaflet (2-) 2.5-5 cm long; plants generally twining; [widespread in our area] |
| ............ 7 Calyx 2.5-7 mm long, clearly shorter than the corolla; [plants of e. GA southward and westward]. |
| ............ ......10 Calyx 2.5-3 (-4) mm long; raceme 4-12 cm long, clearly exceeding the subtending leaves; leaflets 0.8-1.2× as long as wide; [plants of e. GA southward and westward] |
| ............ ......10 Calyx 3.5-7 mm long; raceme 1-4 (-5) cm long, barely if at all exceeding the subtending leaves; leaflets 1.2-2.5× as long as wide; [plants of s. peninsular FL]. |
| ............ ........11 Lower surface of leaflet cinereous-villosulous, the hairs largely obscuring the glands; seeds brown |
| ............ ........11 Lower surface of leaflet inconspicuously puberulent, the yellow glands evident; seeds red or red-and-black. |
| ............ ..........12 Leaflets (4-) 6-8 cm long; seeds red and black; legume 9-12 mm wide |
| ............ ..........12 Leaflets 2-4 (-6) cm long; seeds red; legume 5-8 mm wide |