1	Spurs hooked, 3-22 mm; sepals white or blue.		(2)
+	Spurs straight or nearly so (sometimes tips incurved in A. flavescens), 8-180 mm; sepals blue, white, cream, yellow, pink, or red (A. flavescens with yellow or pink sepals).		(5)
2 (1)	Spurs 14-22 mm; introduced species, at low elevations (0-1500 m).		4 Aquilegia vulgaris
+	Spurs 3-10 mm; native, at high elevations or high latitudes.		(3)
3 (2)	Basal leaves much shorter than stems.		3 Aquilegia brevistyla
+	Basal leaves about as long as stems.		(4)
4 (3)	Sepals and spurs white or nearly so; Wyoming.		2 Aquilegia laramiensis
+	Sepals and spurs blue; Colorado.		1 Aquilegia saximontana
5 (1)	Sepals and spurs blue, white, cream, reddish purple, or occasionally pink (if pink then with no trace of yellow); flowers usually erect (sometimes nodding in A. micrantha); spurs slender (stout at least proximally in A. jonesii), evenly tapered from base.		(6)
+	Sepals and spurs yellow, pink and yellow, or red; flowers erect or nodding; spur shape various.		(9)
6 (5)	Leaflets viscid.		13 Aquilegia micrantha
+	Leaflets not viscid.		(7)
7 (6)	Spurs 8-15 mm.		5 Aquilegia jonesii
+	Spurs 25-70(-72) mm.		(8)
8 (7)	Leaflets glaucous on both sides, 5-14 mm, crowded (primary petiolules 3-15 mm); spurs 25-40 mm.		6 Aquilegia scopulorum
+	Leaflets green adaxially, 13-42(-61) mm, not crowded, primary petiolules (10-)20-70 mm; spurs 28-72 mm.		7 Aquilegia coerulea
9 (5)	Sepals red (at least proximally); spurs red (red proximally, then pink in A. shockleyi), stout (at least proximally), abruptly narrowed near middle, 12-32 mm; flowers nodding or pendent.		(10)
+	Sepals and spurs yellow or pink; spurs slender (except for A. flavescens and A. barnebyi), evenly tapered from base (sometimes abruptly narrowed near middle in A. flavescens and A. micrantha), 10-180 mm; flowers usually erect, sometimes nodding.		(15)
10 (9)	Sepals perpendicular to floral axis; petal blades 0-6 mm.		(11)
+	Sepals parallel to or divergent from floral axis; petal blades 4-12 mm.		(13)
11 (10)	Mouth of spur cut obliquely backward; stamens 17-30 mm.		18 Aquilegia eximia
+	Mouth of spur truncate or with short blade; stamens 12-17 mm.		(12)
12 (11)	Leaflets glaucous on both sides; petal blades 2-5 mm.		17 Aquilegia shockleyi
+	Leaflets green adaxially; petal blades 0-6 mm.		16 Aquilegia formosa
13 (10)	Sepals red proximally, yellow-green distally, not much longer than petal blades; stamens 8-14 mm.		19 Aquilegia elegantula
+	Sepals red or apex green or yellow-green, about 2 times length of petal blades; stamens 14-23 mm.		(14)
14 (13)	Blades of petals pale yellow or yellow-green; basal leaves 2×-ternately compound, leaflets to 17-52 mm; e North America, w to c Texas.		21 Aquilegia canadensis
+	Blades of petals yellow or red and yellow; basal leaves 2-3×-ternately compound, leaflets to 9-26(-32) mm; Arizona, New Mexico, Utah.		20 Aquilegia desertorum
15 (9)	Spurs 42-180 mm.		(16)
+	Spurs 10-40 mm.		(18)
16 (15)	Spurs 72-180 mm; petal blades spatulate.		12 Aquilegia longissima
+	Spurs 42-70 mm; petal blades oblong, not much broadened distally.		(17)
17 (16)	Sepals 14-18 mm wide.		11 Aquilegia hinckleyana
+	Sepals 5-10 mm wide.		10 Aquilegia chrysantha
18 (15)	Spurs yellow, stout, ± incurved, 10-18 mm; flowers nodding.		15 Aquilegia flavescens
+	Spurs yellow to pink or cream, slender, straight, 15-40 mm; flowers erect to nodding.		(19)
19 (18)	Beak 15-18 mm; sepals 9-19 mm, yellow; se New Mexico, w Texas.		9 Aquilegia chaplinei
+	Beak 8-12 mm; sepals not as above: either cream or pink or if yellow, then (15-)20-25 mm; Colorado, Arizona to California.		(20)
20 (19)	Sepals (15-)20-25 mm, petal blades 8-17 mm, spurs 25-40 mm; flowers erect; California.		8 Aquilegia pubescens
+	Sepals 8-20 mm, petal blades 6-10 mm, spurs 14-30 mm; flowers nodding or erect; Colorado, Arizona, Utah.		(21)
21 (20)	Leaflets viscid, green adaxially.		13 Aquilegia micrantha
+	Leaflets not viscid, glaucous on both surfaces.		14 Aquilegia barnebyi