1	"Flowers single or in cymes in axils of leaf-like bracts along parts of or all branches; annuals"	2
1	"Flowers in terminal rounded inflorescences with reduced bracts; perennials with leaves usually longer than 12 mm"	14
2	"Flowers in the axil of one leaf at each node; calyx half to two-thirds as long as the corolla"	3
2	"Flowers in the axil of both leaves at a node; calyx at least as long as corolla"	4
3	"Carpels each with 1 ovule"	"Crassula natans var. minor"
3	"Carpels each with 2–14 ovules"	"Crassula peduncularis"
4	"Inflorescence a flat-topped terminal thyrsoid"	"Crassula glomerata"
4	"Inflorescence elongate, terminal or axillary"	5
5	"Flowers pedicellate and loosely arranged along usually much-branched branches"	6
5	"Flowers sessile or almost so in spike-like inflorescences; plants little-branched mainly from the base"	10
6	"Carpels each with 4–24 ovules"	7
6	"Carpels each with 2 ovules"	8
7	"Seeds less than twice as long as broad, with widely spaced papillae along the vertical ridges; branches erect; calyx-lobes and bracts papillate toward the apex"	"Crassula closiana"
7	"Seeds greater than twice as long as broad, with dense papillae (c. touching one another) along vertical ridges; branches often decumbent; calyx-lobes usually smooth"	"Crassula decumbens var. decumbens"
8	"Flowers 5-merous; much-branched, decumbent annual"	"Crassula thunbergiana subsp. thunbergiana"
8	"Flowers 4-merous; erect or decumbent annuals, or decumbent perennials"	9
9	"Decumbent annuals, branched from base; fruiting calyx 0.5–1(–1.1) mm long, lobes spreading, somewhat fleshy, rarely with membranous margins"	"Crassula tetramera"
9	"Erect annuals or decumbent perennials; fruiting calyx (1.1–)1.2–2.2 mm long, apex of lobes clasping each other or erect and lobes flattened to a more or less membranous margin"	"Crassula colligata subsp. lamprosperma"
10	"Flowers mainly 3-merous"	"Crassula alata var. alata"
10	"Flowers 4- or 5-merous"	11
11	"Follicles often tuberculate, not splitting longitudinally, detaching basally to release seed; styles at least two-thirds as long as bodies of carpels"	"Crassula colorata"
11	"Follicles smooth or papillose, splitting longitudinally from apex on adaxial side, but often detaching basally to release seed; styles up to one-quarter as long as bodies of carpels"	12
12	"Fruiting calyx-lobes incurved between half exposed recurved follicles"	"Crassula exserta"
12	"Fruiting calyx-lobes erect, enclosing erect follicles"	13
13	"Decumbent annuals, branched from base; fruiting calyx 0.5–1(–1.1) mm long, lobes spreading, somewhat fleshy, rarely with membranous margins"	"Crassula tetramera"
13	"Erect annuals or decumbent perennials; fruiting calyx (1.1–)1.2–2.2 mm long, apex of lobes clasping each other or erect and lobes flattened to a more or less membranous margin"	"Crassula colligata subsp. lamprosperma"
14	"Leaves petiolate, rarely sessile, loosely opposite; corolla star-shaped"	"Crassula multicava"
14	"Leaves sessile, stiffly 4-ranked or opposite; corolla tubular"	"Crassula tetragona subsp. robusta"