| 1 | Calyx adnate to rhachis; fruit indehiscent, 1-seeded; annual |
| 1' | Calyx free; fruit a dehiscent many-seeded follicle |
| 2 | Basal leaves forming compact rosettes; plants monocarpic; flowers very numerous in cylindrical or narrowly pyramidal panicles |
| 2' | Basal leaves not forming rosettes; flowers in lax cymes or in corymbs |
| 3 | Basal leaves thinly glandular-pubescent, linear-spathulate |
| 3' | Basal leaves glabrous, rather broadly spathulate |
| 4 | Basal leaves with minutely papillose margins, 4-10 x 2-4 cm |
| 4' | Basal leaves with entire margins, 3-6 x 1-2 cm |
| 5 | Robust perennial 15-60 cm high with sterile shoots; flowers pale yellowish in dense corymbs |
| 5' | Slender annuals without sterile shoots, always less than 15 cm high |
| 6 | Flowers yellow or yellowish; seeds not costate |
| 6' | Flowers white or pinkish; seeds longitudinally ribbed, costate or reticulate |
| 7 | Follicles stellate-patent, smooth with a conspicuous lateral nerve; stem and rhachis glabrous |
| 7' | Follicles erect or spreading, rugulose-papillose; upper parts of stem and rhachis glandular or glabrous |
| 8 | Petals 1.5-3 mm long; leaves ciliate-denticulate, 3-4 x 1.5-2 mm; follicles c. 2.5 mm long |
| 8' | Petals 3-5 mm long; leaves glabrous, entire, 3-12 x 2-6 mm; follicles c. 3.5 mm long |
| 9 | Follicles erect or suberect, c. 1-1.5 mm wide at base; inflorescence usually lax with spreading or recurved branches |
| 9' | Follicles spreading, c. 1.8 mm wide at base; inflorescence usually compact with erecto-patent or slightly recurved branches |
