1	"Leaves simple"	2
1	"Leaves compound"	3
2	"Leaves evergreen, with 6--8 coarse, generally terminal spines; petals orange"	"Berberis darwinii"
2	"Leaves deciduous, with >> 8, small, marginal spines; petals yellow"	"Berberis vulgaris"
3	"Bud scales persistent among upper leaves, 15--45 mm, thick, lanceolate; leaflets +- palmately veined"	"Berberis nervosa"
3	"Bud scales generally deciduous, < 5 mm, thin, ovate to deltate; leaflets generally pinnately veined"	4
4	"Inflorescence open, flowers generally < 10; petiole generally < 2 cm; terminal leaflets generally lanceolate, oblong, or narrowly elliptic --- SW, D"	5
4	"Inflorescence dense, flowers > 10; petiole generally > 2 cm (0--3 cm in <i>Berberis pinnata</i>); terminal leaflets generally ovate to wide-elliptic"	9
5	"Leaflets generally 3, terminal sessile"	"Berberis harrisoniana"
5	"Leaflets 3--9, terminal stalked"	6
6	"Leaflets flat to +- wavy, not folded along midrib, serrate, spines generally > 8 per side, +- 1 mm"	"Berberis nevinii"
6	"Leaflets wavy, generally folded along midrib, +- lobed, spines generally 3--8 per side, 1--4 mm"	7
7	"Terminal leaflet generally < 2 &times; width; berries yellow-red when fresh, +- glaucous, not inflated"	"Berberis higginsiae"
7	"Terminal leaflet generally > 2 &times; width; berries blue-black when fresh, heavily glaucous, not inflated or inflated only due to insect parasitism"	8
8	"Terminal leaflet generally lance-ovate, length generally < 3 &times; width; flowers 8--12; fruit yellow- to purple-red"	"Berberis fremontii"
8	"Terminal leaflet generally narrow-lanceolate, length generally > 3 &times; width; flowers 3--5; fruit red-brown to dark purple"	"Berberis haematocarpa"
9	"Leaflet margin strongly wavy, thick, generally hard, spines 6--10(12) per side, 2--5 mm"	"Berberis aquifolium var. dictyota"
9	"Leaflet margin wavy to flat, +- thin, not hard, spines generally > 10 per side (to 0 in <i>Berberis pinnata</i>), 1--2 mm"	10
10	"Petioles generally > 3 cm; leaflets generally 5--9"	11
10	"Petioles generally 1--3 cm; leaflets generally 7--11"	12
11	"Stems ascending to erect, generally 1--2 m; leaflets generally shiny adaxially"	"Berberis aquifolium var. aquifolium"
11	"Stems spreading to erect, generally < 0.8 m; leaflets generally dull adaxially"	"Berberis aquifolium var. repens"
12	"Leaflet margins generally flat, spines generally < 1 mm; upper stems reclining to weakly erect; plant 2--4 m"	"Berberis pinnata subsp. insularis"
12	"Leaflet margins generally wavy, spines generally > 1 mm; upper stems generally erect; plant generally < 2 m"	"Berberis pinnata subsp. pinnata"