Flowers usually actinomorphic, bisexual and solitary or borne in cymose inflorescences. Perianth 1- or 2-whorled, 4- or 5-lobed, sometimes the lobes almost free. Stames 4-numerous but frequently with numerous petaloid staminodes. Ovary superior, inferior or half-inferior, 1–many-locular, each loculus with 1–many ovules.
| | Key to the genera | |
| 1 | Perianth deeply 5-lobed | Galenia |
| Perianth tubular-2 | |
| 2 | Ovary superior | 3 |
| Ovary inferior or half-inferior
Back to | 7 |
| 3 | Styles 1 or 2; ovary 1- or 2-locular | 4 |
| Styles 3 or more; ovary with 3 or more loculi
Back to 2 | 5 |
| 4 | Style 1; ovary 1-locular; capsule circumsciss, the operculum not dehiscent | Trianthema |
| Styles 2; ovary 2-locular; capsule circumsciss with the operculum longitudinally dehiscent
Back to 3 | Zaleya |
| 5 | Stamens 4–12, in 4 groups | Gunniopsis |
| Stamens more than 12
Back to 3 | 6 |
| 6 | Stamens c. 20, uniformly distributed | Sesuvium |
| Stamens numerous, either in 4 bundles or in 2 or 3 whorls
Back to 5 | Gunniopsis |
| 7 | Each loculus with a single ovule; petaloid staminodes absent | Tetragonia |
| Each loculus with numerous ovules, petaloid staminodes usually present
Back to 2 | 8 |
| 8 | Plants annual or biennial | 9 |
| Plants perennial
Back to 7 | 11 |
| 9 | Leaves glabrous; plants prostrate | Disphyma |
| Leaves with vesicular hairs; plants erect or almost erect
Back to 8 | 10 |
| 10 | Placentation axile; leaves alternate on flowering branches; stamens many; staminodes white | Mesembryanthemum |
| Placentation parietal; leaves all opposite; stamens 5–10; staminodes yellow
Back to 9 | Micropterum |
| 11 | Perianth segments 4; leaves ovate, often cordate at base | Aptenia |
| Perianth segments 5; leaves linear, terete or angled
Back to 8 | 12 |
| 12 | Leaves soon falling, with only leaf bases persistent; placentation axile | Psilocaulon |
| Leaves persistent; placentation parietal or basal
Back to 11 | 13 |
| 13 | Perianth segments 5, more or less equal and equidistant; fruit capsular, opening when wet | 14 |
| Perianth segments 5, with 2 more or less opposite and commonly larger than the others; fruit fleshy, indehiscent
Back to 12 | 15 |
| 14 | Leaves more or less rounded in cross section; flowering branches with very short internodes but often with long pedicels | Disphyma |
| Leaves more or less triquetrous, at least the dorsal angle evident; flowering branches with conspicuous internodes
Back to 13 | Lampranthus |
| 15 | Styles 6 or more; stems elongated and creeping | Carpobrotus |
| Styles 4 or 5; stems not much elongated, decumbent or ascending
Back to 13 | Sarcozona |
