| 1 | Flowers in dense globose clusters or verticillasters spaced along the flowering stem |
| 1' | Flowers not in dense globose clusters or verticillasters |
| 2 | Calyx distinctly inflated at anthesis |
| 2' | Calyx not distinctly inflated at anthesis |
| 3 | Calyx 10-nerved; petals shortly lobed; plant annual |
| 3' | Calyx 20-nerved; petals very deeply bilobed; plant perennial |
| 4 | Plants perennial, with hard, woody rootstocks |
| 4' | Plants annual, base seldom hard or woody |
| 5 | Leaves bordered with several rows of short, stiff, recurved hairs, otherwise glabrous; plant suffruticose; leaves in tufts at ends of woody branches |
| 5' | Leaves pubescent all over; plant not suffruticose, nor with leaves in tufts at the end of woody branches |
| 6 | Flowers rather few and distant in very lax, narrow panicles; petals pink or pink-tinged |
| 6' | Flowers numerous, in large spreading, sometimes congested panicles; petals white or greenish |
| 7 | Plant with female (calyx 3-5 mm long) and hermaphrodite flowers (calyx 5-11 mm long); flowers usually congested; capsule 3-sulcate or trigonous |
| 7' | Plant with uniform flowers; in spreading panicles; capsule not trigonous |
| 8 | Petal-lobes rounded, less than 1 cm long; calyx thinly pubescent, often purplish; flowers erect |
| 8' | Petal-lobes narrowly oblong or strap-shaped, 1-1,3 cm long; calyx glabrous (calyx-teeth ciliate), pallid; flowers nodding |
| 9 | Calyx 30- or 60-nerved; calyx-teeth long, narrow, subulate or almost so; anthophore very short |
| 9' | Calyx 10-nerved, teeth not normally subulate (except in S. tridentata) |
| 10 | Calyx 30-nerved; capsule 1.6-2 cm. long with a slender neck; flowers usually deep reddish-pink |
| 10' | Calyx 60-nerved; capsule about 1 cm long, without a slender neck; flowers usually pale pink |
| 11 | Calyx 20-30 mm long |
| 11' | Calyx less than 20 mm long |
| 12 | Calyx nerves distinctly anastomosing; cauline leaves dense and imbricate; carpophore 3-7 mm long |
| 12' | Calyx nerves obscurely branched or indistinctly anastomosing (but then with almost wanting carpophore) |
| 13 | Cauline leaves linear or subulate, with a long slender acumen |
| 13' | Cauline leaves broader, not linear or subulate, nor with a long, slender acumen |
| 14 | Capsule broadly ovoid or subglobose; seeds papillose; coronal scales triangular, acuminate |
| 14' | Capsule narrowly ovoid or ellipsoid; seeds bluntly ridged; coronal scales oblong, blunt |
| 15 | Anthophore very short (less than 2 mm long) or wanting; calyx rather abruptly constricted at base, or rounded |
| 15' | Anthophore more than 2 mm long; calyx often tapering gradually to base |
| 16 | Plant quite glabrous, glaucous; flowers small, pink |
| 16' | Plant pubescent or glandular-pilose |
| 17 | Cauline leaves usually less than 1 cm. long, fleshy; flowers small, pink; stems spreading; seaside plant |
| 17' | Cauline leaves usually exceeding 1 cm in length, not fleshy |
| 18 | Calyx distinctly constricted at mouth in fruiting specimens |
| 18' | Calyx not much constricted at mouth in fruiting specimens |
| 19 | Petals bright carmine; inflorescence regularly dichotomous with spreading branches; calyx distinctly ribbed |
| 19' | Petals paler pink or whitish, sometimes blotched crimson, or wanting; inflorescence not regularly dichotomous |
| 20 | Calyx-teeth subulate, about 5 mm long, conspicuous; petals small, inconspicuous |
| 20' | Calyx-teeth not subulate; petals usually conspicuous |
| 21 | Calyx distinctly ribbed; petals whitish; flowers usually distant |
| 21' | Calyx not ribbed; petals pink or crimson-blotched; flowers usually numerous in a raceme-like monochasium |
| 22 | Capsule narrowly ovoid-cylindrical; calyx with distinct anastomosing veins; seeds not winged; flowers in long raceme-like monochasia |
| 22' | Capsule broadly ovoid; calyx without distinct anastomosing veins; seeds winged; inflorescence often irregular |
| 23 | Calyx nerves conspicuously pilose, often reddish; petals pink, longer than calyx |
| 23' | Calyx nerves not conspicuously pilose, greenish; petals whitish or pinkish or wanting, often shorter than calyx |
| 24 | Inflorescence regularly dichotomous with spreading branches; calyx distinctly ribbed |
| 24' | Inflorescence not regularly dichotomous with spreading branches; calyx not distinctly ribbed |
| 25 | Inflorescence a rather crowded, much-branched terminal cluster of dichasia |
| 25' | Inflorescence not crowded, either monochasial and raceme-like, or a lax dichasium |
| 26 | Calyx whitish (sometimes tinged purple) papery; flowers small; petals seldom more than 1 cm long; plant subglabrous, glaucous |
| 26' | Calyx purplish, glandular-hairy; flowers rather large; petals 1-5 cm long; plant pubescent or glandular-hairy |
| 27 | Bracts herbaceous, green or purplish; calyx 1-1.3 cm long; seeds bluntly ridged or striate |
| 27' | Bracts membranous, whitish; calyx 1.4-1.8 cm long; seeds bluntly papillose |
| 28 | Calyx at anthesis broadly oblong or turbinate, abruptly narrowed at base; petals often minute or wanting |
| 28' | Calyx at anthesis rather narrowly clavate, tapering to base |
| 29 | Flowers shortly pedicellate or subsessile in narrow raceme-like monochasia |
| 29' | Flowers distinctly pedicellate, in lax dichasia or monochasia |
| 30 | Basal leaves forming persistent tufts or rosettes at anthesis; capsule narrowly ovoid-oblong, 7 x 4 mm; seeds not winged |
| 30' | Basal leaves not forming tufts or rosettes at anthesis; capsule broadly ovoid or subglobose, 5-7 x 5-6 mm; seeds winged |
| 31 | Inflorescence repeatedly branched; petals deeply bifid, pale pink or whitish; plant erect or suberect |
| 31' | Inflorescence monochasial, or sparsely and irregularly branched; petals bright pink, truncate or shallowly emarginate; plant usually sprawling |
