1	"Plant scapose; cauline leaves 0"	2
1	"Plant not scapose; cauline leaves present"	5
2	"All or at least early flowers 1 from basal rosette"	Idahoa
2	"All flowers in racemes"	3
3	"Flowers yellow"	Diplotaxis
3	"Flowers white, lavender, or purple"	4
4	"Perennial herb; petals 4–5.5(7) mm"	Cardamine
4	"Annual; petals 1.2–1.5 mm"	Subularia
5	"Cauline leaves petioled; plant aquatic, rooting from proximal nodes"	Nasturtium
5	"Cauline leaves sessile; plant terrestrial, not rooting from proximal nodes"	6
6	"Stamens 2"	Lepidium
6	"Stamens 6(4)"	7
7	"All stamens well exserted beyond petals; ovary stalk above receptacle distinct in flower"	8
7	"At least some stamens included; ovary stalk above receptacle 0 in flower"	9
8	"Sepals spreading to reflexed; petals yellow to white, 1.3–2 cm"	Stanleya
8	"Sepals generally ± erect; petals purple, lavender, or white, 0.6–1.2(1.6) cm"	Thelypodium
9	"Stamens in 3 pairs of unequal length; petals crinkled or channeled"	10
9	"Stamens 4 long, 2 short; petals generally not crinkled, not channeled"	11
10	"Fruit cylindric; seed wings 0"	Caulanthus
10	"Fruit flattened; seeds generally winged"	Streptanthus
11	"Ovary, young fruit with 1–2(4) ovules or seeds"	12
11	"Ovary, young fruit with (4)6–300 ovules or seeds"	14
12	"Young fruit not reflexed"	Lepidium
12	"Young fruit reflexed"	13
13	"Petals yellow"	Isatis
13	"Petals white or ± purple-tinged"	Thysanocarpus
14	"Petals yellow"	15
14	"Petals white, lavender, pink, purple, or violet"	19
15	"Young fruit reflexed"	Caulanthus
15	"Young fruit spreading to erect"	16
16	"Petals (6)8–30 mm, clawed"	Brassica
16	"Petals 0.5–9(12) mm (or 0), clawed or not, narrowed to base"	17
17	"Cauline leaves cordate-clasping"	Conringia
17	"Cauline leaves basally lobed"	18
18	"Ovary, young fruit linear; stem angular distally"	Barbarea
18	"Ovary, young fruit spheric to ovoid or oblong; stem generally not angular distally"	Rorippa
19	"Ovary, young fruit ovate, round, or cordate"	20
19	"Ovary, young fruit linear"	21
20	"Perennial herb; seeds smooth"	Noccaea
20	"Annual; seeds striate"	Thlaspi
21	"Petals not clawed, gradually narrowed to base"	Boechera
21	"Petals clawed"	22
22	"Petals 15–30 mm"	Brassica
22	"Petal 4.5–12(15)"	23
23	"Young fruit reflexed"	Caulanthus
23	"Young fruit erect to spreading"	Thelypodium