1	Legume spirally coiled		(2)
+	Legume not spirally coiled		(8)
2 (1)	Perennial herbs or shrubs; legume spineless		(3)
+	Annual or biennial herbs; legume with spines or tubercles		(5)
3 (2)	Shrubs.		9 M. arborea
+	Herbs		(4)
4 (3)	Legume tightly coiled in 2-4(-6) spirals, center solid or nearly so; corolla variable in color, white, deep blue, to dark purple.		7 M. sativa
+	Legume loosely coiled in 1-1.5 spirals, center hollow; corolla yellow to brownish purple.		8 M. ×varia
5 (2)	Leaflets obviously hairy; legume globose, less than 4.5 mm in diam		(6)
+	Leaflets glabrous or glabrescent; legume discoid, 4-10 mm in diam		(7)
6 (5)	Petiole shorter than peduncle, stipule entire or obscurely serrate, leaflets densely hairy; inflorescence 2-10-flowered.		10 M. minima
+	Petiole longer than peduncle, stipule small, incised, leaflets sparsely pilose; inflorescence 1- or 2-flowered.		11 M. praecox
7 (5)	Petiole not more than 2 × as long as peduncle, stipule laciniate or lacerate, leaflets without dark blotch.		12 M. polymorpha
+	Petiole 2-5 × as long as peduncle, stipule triangular, incised to laciniate, leaflets with a dark central blotch.		13 M. arabica
8 (1)	Legume less than 3 mm.		1 M. lupulina
+	Legume more than 8 mm		(9)
9 (8)	Legume falcate or linear, straight or curved to arcuate, less than 3 mm wide		(10)
+	Legume oblong to semilunar, more than 4 mm wide		(12)
10 (9)	Plants perennial; flowers in crowded pedunculate racemes.		6 M. falcata
+	Plants annual; flowers solitary to few in sessile to shortly stalked clusters		(11)
11 (10)	Flowers 1 or 2(or 3), 6-8 mm, sessile; legume more than 40 mm.		14 M. monantha
+	Flowers 2-5, 4-5 mm, shortly pedunculate; legume less than 30 mm.		15 M. orthoceras
12 (9)	Plants densely pubescent; flowers yellow, ca. 5 mm.		5 M. edgeworthii
+	Plants glabrous or slightly puberulent; flowers yellow with scarlet spot, more than 6 mm		(13)
13 (12)	Legume 5-9 mm wide; stems glabrous; leaflets (15-)20-30 × (8-)15-25 mm		2 M. platycarpos
+	Legume less than 6 mm wide; stems ± puberulent; leaflets 6-18(-25) × (1.5-)3-12 mm		(14)
14 (13)	Flowers 4 or 5 in a scattered thyrse; leaflets ovate to orbicular; stipules hastate.		3 M. archiducis-nicolaii
+	Flowers (4-)6-9(-15) in dense fascicles; leaflets cuneate-linear to oblanceolate; stipules lanceolate.		4 M. ruthenica