1	Leaf segments large, lanceolate to oblong or oval to ovate. 2 or more cm long		(2)
+	Leaf segments small; filiform to linear, 1-3 cm long or oblong to ovate, up to 1 cm long		(5)
2 (1)	Leaf segments lanceolate to oblong, more than 5 cm long		(3)
+	Leaf segments c. 2 cm long, oval to ovate		Ferula lehmannii
3 (2)	Petals white, persistent. Fruit vittae inconspicuous, minute		Ferula assa-foetida
+	Petals yellow, deciduous. Fruit vittae 1-many, conspicuous		(4)
4 (3)	Margin of leaf segments entire or sinuate. Fruit 10-12 mm long		Ferula narthex
+	Margin of the leaf segments serrate. Fruit 15-18 mm long		Ferula jaeschkeana
5 (1)	Leaf segments filiform to linear, 1-3 cm long		(6)
+	Leaf segments small lobed, oblong to oval or ovate, up to 1 cm long		(8)
6 (5)	Leaf base inflated, large, up to 15 cm long		Ferula oopoda
+	Leaf base not inflated, up to 7 cm long		(7)
7 (6)	Rays 9-11, 5-11 cm long		Ferula baluchistanica
+	Rays c. 25, 3 cm long		Ferula hindukushensis
8 (5)	Pinnae oblong to oval, 1-5 mm long, glabrous or hispid		(9)
+	Pinnae oblong, up to 1 cm long, lobed; lobes 2-3 mm long, oval to oblong, puberulous to hispid		(10)
9 (8)	Leaves glabrous. Plants c. 50 cm tall		Ferula stewartiana
+	Leaves hispid. Plants 1.5 to 2 m tall		Ferula ovina
10 (8)	Fruit furrows 2-3-vittate		Ferula costata
+	Fruit furrows 1. vittate		Ferula reppiae