1	Racemes bracteate.		32 Cardamine pattersonii
+	Racemes ebracteate		(2)
2 (1)	Cauline leaves (at least some) simple (rarely absent)		(3)
+	Cauline leaves pinnately or palmately compound, 3-25-foliolate, sometimes pinnatisect and appearing compound		(14)
3 (2)	Petioles of cauline leaves auriculate basally.		8 Cardamine clematitis (in part)
+	Petioles of cauline leaves not auriculate basally (rarely these leaves absent)		(4)
4 (3)	Plants with distinct caudices; rhizomes absent; cauline leaves 0 or 1 (or 2).		3 Cardamine bellidifolia
+	Plants without caudices; rhizomes present; cauline leaves 2-23 (sometimes 1 in C. purpurea)		(5)
5 (4)	Petals 0-0.7 mm; fruiting pedicels 0.5-2(-4) mm.		21 Cardamine longii
+	Petals 3.5-28 mm; fruiting pedicels (5-)7-50 mm		(6)
6 (5)	Ovules 40-80 per ovary.		37 Cardamine rotundifolia
+	Ovules 10-24 per ovary		(7)
7 (6)	Fruits 0.8-1.6 cm × 0.8-1 mm; anthers ovate, ca. 0.2 mm; petals 3.5-5 × 1.2-1.8 mm.		24 Cardamine micranthera
+	Fruits (1.5-)2-6 cm × 1.2-4 mm; anthers oblong to linear, 0.6-3 mm; petals (5-)7-28 × 3-7 mm		(8)
8 (7)	Rhizomes (not fleshy), 1-3 mm diam.; rhizomal leaves usually absent		(9)
+	Rhizomes (fleshy), (3-)4-18 mm diam.; rhizomal leaves present		(11)
9 (8)	Petals 15-28 mm; sepals 6-8 mm.		10 Cardamine constancei
+	Petals 5-12 mm; sepals 2-4.5 mm		(10)
10 (9)	Cauline leaves (3-)5-17(-23); petals white, 7-12 mm; fruits (2-)2.5-3.7(-4) cm; stems 2-7(-10.2) dm.		11 Cardamine cordifolia
+	Cauline leaves 1-3; petals usually purple to pink, rarely white, 5-7(-9) mm; fruits 1.5-2.5 cm; stems to 1.5 dm.		36 Cardamine purpurea (in part)
11 (8)	Petals 3-5 mm wide; fruits 1.4-2 mm wide; e, c North America		(12)
+	Petals 4-8 mm wide; fruits 2-4 mm; California		(13)
12 (11)	Petals usually white, rarely pale pink; stem distally glabrous or trichomes 0.02-0.1 mm.		6 Cardamine bulbosa
+	Petals usually purple or pink, rarely white; stem distally with trichomes (0.2-)0.3-0.6(-0.8) mm.		15 Cardamine douglassii
13 (11)	Petals white or pale rose, rarely purple, 8-13(-17) mm; ovules 12-22 per ovary; stems (2-)2.7-6(-7) dm; rhizomal leaves usually 3(-7)-foliolate, rarely simple.		7 Cardamine californica (in part)
+	Petals usually purple or pink, rarely white, 14-18 mm; ovules 10-14 per ovary; stems 1-3 dm; rhizomal leaves simple.		30 Cardamine pachystigma
14 (2)	Petiole of cauline leaves basally auriculate		(15)
+	Petiole of cauline leaves not basally auriculate		(16)
15 (14)	Cauline leaves 3-foliolate; perennials (rhizomatous).		8 Cardamine clematitis (in part)
+	Cauline leaves (9-)13-25-foliolate; annuals or biennials.		20 Cardamine impatiens
16 (14)	Annuals or biennials, not rhizomatous		(17)
+	Perennials, rhizomatous		(22)
17 (16)	Rachises strongly flexuous to geniculate; petals 6-8 mm; fruits (2.5-)3-4.6 × 1.7-2.1 mm.		22 Cardamine macrocarpa
+	Rachises not flexuous (slightly so in C. flexuosa); petals 1.5-4(-5) mm; fruits (0.5-) 1-2.5(-3.2) × 0.6-1.5 mm		(18)
18 (17)	Basal leaves rosulate, persistent to anthesis		(19)
+	Basal leaves not rosulate, often withered by anthesis		(20)
19 (18)	Stamens usually 4, rarely 5 or 6; fruiting pedicels erect to ascending; fruitsoften appressed to rachis, valves glabrous; seeds narrowly margined.		18 Cardamine hirsuta
+	Stamens 6; fruiting pedicels divaricate-ascending; fruits often not appressed to rachis, valves sparsely pubescent or glabrous; seeds often not margined (wingless).		29 Cardamine oligosperma
20 (18)	Lateral leaflets of cauline leaves narrowly oblong, linear or filiform, 1-3 mm wide; fruits 0.6-0.9 mm wide.		31 Cardamine parviflora
+	Lateral leaflets of cauline leaves orbicular, ovate, elliptic, or oblong, 4-25 mm wide; fruits 0.8-1.5 mm wide		(21)
21 (20)	Rachises slightly flexuous; ovules 18-40 per ovary; plants of waste grounds, disturbed sites.		17 Cardamine flexuosa
+	Rachises straight; ovules 40-80 per ovary; plants of margins of wet habitats.		34 Cardamine pensylvanica
22 (16)	Rhizomes tuberiform, usually segmented, fragile (segments fusiform, ovoid, oblong, or globose)		(23)
+	Rhizomes cylindrical, segments not fragile		(29)
23 (22)	Cauline leaves biternate, distal lobes linear.		14 Cardamine dissecta
+	Cauline leaves 3-11-foliolate, distal lobes not linear		(24)
24 (23)	Cauline leaves 5-11-foliolate.		33 Cardamine penduliflora
+	Cauline leaves usually 3-, sometimes 5-7-foliolate, rarely simple		(25)
25 (24)	Rhizomes moniliform; e, c United States		(26)
+	Rhizomes not moniliform; Pacific North America		(27)
26 (25)	Cauline leaves different from rhizomal leaves, usually alternate, rarely opposite.		2 Cardamine angustata
+	Cauline leaves similar to rhizomal leaves, usually whorled or opposite, rarely alternate.		9 Cardamine concatenata
27 (25)	Middle cauline leaves 5- or 7-foliolate; sepals 1.7-2 mm; petals 4-6 mm.		28 Cardamine occidentalis
+	Middle cauline leaves 3(-5)-foliolate; sepals 3.5-5.5 mm; petals 8-15 mm		(28)
28 (27)	Cauline leaves 2-5; stems (2-)2.7-6(-7) dm; ovules 12-22 per ovary; petals white or pale rose; California.		7 Cardamine californica (in part)
+	Cauline leaves 1-3; stems 0.5-2(-3) dm; ovules 8-16 per ovary; petals usually purple to pale pink, rarely white; British Columbia, California, Oregon, Washington.		26 Cardamine nuttallii
29 (22)	Cauline leaves pinnatisect or (7-)9-21-foliolate		(30)
+	Cauline leaves 3-5(-7)-foliolate		(31)
30 (29)	Leaves thick, veins impressed.		27 Cardamine nymanii
+	Leaves thin, veins raised.		35 Cardamine pratensis
31 (29)	Rhizomes compact at stem base, stolons present.		16 Cardamine flagellifera
+	Rhizomes slender, stolons absent		(32)
32 (31)	Rhizomes fleshy, with dentate leaf scars; plants of North America east of the 110th meridian		(33)
+	Rhizomes not fleshy, without dentate leaf scars; plants of North America west of the 110th meridian		(34)
33 (32)	Rhizomes somewhat uniform in diameter; cauline leaves (sub) opposite.		13 Cardamine diphylla
+	Rhizomes not uniform in diameter (distinctly constricted at intervals); cauline leaves usually alternate, rarely subopposite.		23 Cardamine maxima
34 (32)	Plants cespitose, hirsute; petals purple or pink, rarely white.		36 Cardamine purpurea (in part)
+	Plants not cespitose, glabrous or sparsely pubescent or pilose; petals usually white, rarely pink		(35)
35 (34)	Basal leaves rosulate; fruiting racemes subumbellate.		39 Cardamine umbellata
+	Basal leaves absent; fruiting racemes not subumbellate		(36)
36 (35)	Sepals 1.2-1.5 mm; petals 2-2.5 × 0.8-1 mm; anthers 0.2-0.3 mm.		19 Cardamine holmgrenii
+	Sepals 2-5 mm; petals 3.5-15 × 1.5-8 mm; anthers 0.7-1.5 mm		(37)
37 (36)	Rhizomal leaves absent; ovules 14-28 per ovary.		5 Cardamine breweri
+	Rhizomal leaves present; ovules 6-16(-24) per ovary		(38)
38 (37)	Stems hirsute at base; cauline leaves (3 or) 4-8.		1 Cardamine angulata
+	Stems usually glabrous at base, rarely sparsely pilose; cauline leaves 1-3 (or 4)		(39)
39 (38)	Rhizomal leaves palmately or subpalmately compound, fleshy; Montana.		38 Cardamine rupicola
+	Rhizomal leaves pinnately compound, not fleshy; Alaska, Northwest Territories, Yukon		(40)
40 (39)	Rhizomal leaves with terminal leaflet blade broadly obovateto suborbicular, margins often 3-5-toothed.		4 Cardamine blaisdellii
+	Rhizomal leaves with terminal leaflet blade linear, narrowly oblong, narrowly oblanceolate, ovate, or elliptic, margins entire		(41)
41 (40)	Cauline leaves with terminal leaflet narrowly lanceolate to linear, 1-3.2(-4) cm.		12 Cardamine digitata
+	Cauline leaves with terminal leaflet ovate to elliptic, 0.6-1.3 cm.		25 Cardamine microphylla