1	Calyx teeth less than 5 mm long		(2)
+	Calyx teeth more than 5 mm long		(3)
2 (1)	Calyx teeth c. 2 mm long, vexillum panduriform		Astragalus strobiliferus
+	Calyx teeth c. 4.5-5 mm long, vexillum not panduriform		Astragalus ghaznianus
3 (1)	Calyx longer than the corolla		Astragalus neo-spinosus
+	Calyx shorter than the corolla		Astragalus ptilocephalus