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1 Terrestrial, proastrate or upright, stems not inflated.
..2 Prostrate perennial; leaves with 3-19 leaflets; stipules basifixed; loment articles separated by a joint and also an isthmus; calyx campanulate; [of dry, sandy or of disturbed areas].
..2 Erect or ascending annual; leaves with 21-51 or more leaflets; stipules peltate or medifixed; loment articles separated by only a joint; calyx bilabiate; [of moist to wet habitats].
....3 Leaflets with 2-4 longitudinal nerves; mature fruit stipe 1.5-3 mm long
......4 Loment sinuses either notched asymmetrically, or not notched as deeply; [collectively widespread]
........5 Mature fruit stipe 12-25 mm long; corolla (10-) 12-15 mm long; fruit segments 5-7 mm long, 4.5-6.5 mm wide; paired bracts subtending each flower toothed (rarely entire); standard greenish-yellow with distinct dark-red veins; leaflets 6-25 mm long, 2-5 mm wide
........5 Mature fruit stipe 4-8 (-10) mm long; corolla 7-13 (-15) mm long; fruit segments 4-6 mm long, 3.5-6 mm wide; paired bracts subtending each flower toothed or entire; standard pale orange or reddish-orange, the veins usually indistinct; leaflets 2.5-25 mm long, 1-4 mm wide.
..........6 Paired bracts subtending each flower entire (rarely toothed); leaflets 2.5-13 mm long, 1-2.5 mm wide; fruit segments 4-5 mm long, 3.5-5 mm wide
..........6 Paired bracts subtending each flower toothed (rarely entire); leaflets 6-25 mm long, 1.5-4 mm wide; fruit segments 5-6 mm long, 5-6 mm wide