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| 1 Flowers in axillary clusters; leaflets broadly obovate, 0.5-1 cm long |
| 1 Flowers in axillary or terminal racemes; leaflets rotund, broadly ovate, broadly elliptic, or narrowly elliptic, the larger > 1 cm long. |
| ..2 Loments linear, ca. 1.5 mm wide, the sinuses symmetrical above and below, only slightly constricted relative to the width of the loment |
| ..2 Loments elongate, > 3 mm wide, the sinuses assymmetrical, notched more deeply below, and obviously constricted to < half of the width of the loment. |
| ....3 Flowers in simple terminal racemes; leaflets mostly > 2.5× as long as wide |
| ....3 Flowers either in axillary racemes or in terminal panicles; leaflets mostly 0.9-2.0× as long as wide. |
| ......4 Stipules ovate, persistent, slightly to strongly clasping at the base, 6-12 mm long. |
| ........5 Leaflets ovate, 1.2-1.9× as long as wide; flowers white to yellowish; loment uncinate-puberulent only along the sutures |
| ........5 Leaflets ovate, 0.8-1.1× as long as wide; flowers blue-purple; loment uncinate-puberulent over the surface |
| ......4 Stipules lanceolate to linear (or deltate in D. humifusum), usually quickly deciduous, not clasping at the base, 2-8 mm long. |
| ..........6 Terminal leaflet 1.4-2.0× as long as wide, 3.0-7.0 cm long; loment segments 6-8 mm long; stipules 4-8 mm long, ovate to lance-acuminate |
..........6 Terminal leaflet 0.9-1.2× as long as wide, 1.5-2.3 cm long; loment segments 4-5 mm long; stipules lanceolate, 1-5 mm long |