1	Calyx either truncate or with lobes not contorted, leaving the corolla exposed in bud; trees or shrubs with 4-merous flowers; seeds often provided with dorsal hyaline papillae	Dichaetanthera
–	Calyx-lobes always developed, contorted and concealing the corolla in young bud stage; herbs, or if shrubs then flowers always 5-merous; seeds tuberculate, smooth, ridged or foveolate, without hyaline papillae	2
2	Flowers involucrate, solitary or in heads; calyx-lobes persistent; intersepalar appendages absent; fruits capsular or baccate	3
–	Flowers not involucrate (except in Dissotisspeciosa), solitary, glomerulate, panicled or racemose; calyx-lobes caducous or persistent; intersepalar appendages present; fruits capsular or irregularly dehiscent, never baccate	5
3	Shrub with 1-flowered inflorescences; stamens isomorphic, with two ventral and one dorsal appendage, no distinct pedoconnective and erect anthers	Cailliella
–	Herbs, or if shrubs then flowers several per inflorescence; stamens not as above, with two ventral appendages only, and pedoconnective usually well-developed	4
4	Fruit fleshy, baccate; stamens isomorphic (except T.cornifolium), with erect anthers; hypanthium with hairs often arranged in rings (but sometimes glabrous or hairy all over)	Tristemma
–	Fruit dry, capsular; stamens heteromorphic (except M.porteresii), with anthers patent or curved; hypanthium glabrous or with hairs not arranged in rings	Melastomastrum
5	Stems, leaves, and inflorescences with stellate hairs, sometimes with simple hairs present as well; leaves sessile, amplexicaul	Argyrella
–	Stems, leaves and inflorescences with simple or dendritic hairs, or sometimes glabrescent; leaves usually petiolate	6
6	Shrubs	7
–	Herbs, sometimes ± woody at base	11
7	Calyx-lobes notched at apex, asymmetrical, caducous; leaves deciduous	Nothodissotis
–	Calyx-lobes entire, ± symmetrical, caducous or persistent (always persistent if leaves deciduous)	8
8	Intersepalar appendages absent or reduced to a bristle; calyx-lobes persistent; hairs on stems and leaves ± bulbous at base; leaves deciduous or not	9
–	Intersepalar appendages well-developed; calyx-lobes caducous (sometimes tardily so); hairs on stems and leaves not bulbous at base; leaves never deciduous	10
9	Inflorescence a 1−3(−7) flowered cyme; intersepalar appendages present; stamens isomorphic; leaves small, 1.5−2.5 × 1−1.5 cm	Dionychastrum
–	Inflorescence a many-flowered panicle; intersepalar appendages absent; stamens usually dimorphic; leaves much larger	Dissotidendron
10	Anthers isomorphic, opening by an extrorse pore; leaves distinctly bicoloured, dark green above and yellowish-green beneath	Pseudosbeckia
–	Anthers usually dimorphic, opening by an introrse pore; leaves not as above	Dissotis (D. sects. Macrocarpae, Squamulosae, Sessilifoliae)
11	Calyx-tube accrescent in fruit, developing a long neck with longitudinal ribs; intersepalar appendages absent; stamens dimorphic	Dupineta
–	Calyx tube not accrescent (except Dissotistubulosa) and lacking longitudinal ribs; intersepalar appendages usually present; stamens dimorphic or isomorphic	12
12	Seeds longitudinally ridged or foveolate, with a (sometimes very short) basal aril; stems creeping at base; staminal appendages bilobed or bipartite in outer stamens; hypanthium with stalked stellate emergences (except H.decumbens with simple hairs)	Heterotis
–	Seeds tuberculate or smooth, not arillate; stems usually erect, or if creeping (Guyonia), then staminal appendages entire in outer stamens; hypanthium usually glabrous or with simple hairs (in Antherotoma sometimes with stellate emergences)	13
13	Seeds with parallel rows of tubercles; staminal appendages bilobed or bipartite; flowers 4- or 5-merous; calyx-lobes persistent or caducous; hypanthium with simple eglandular hairs or stellate emergences, rarely glabrous (Chaetolepisgentianoides)	Dissotis and allies (Antherotoma, C.gentianoides, D.sect.Dissotis, D.congolensis, D.tubulosa, African “Osbeckia”)
–	Seeds smooth, or with tubercles not arranged in parallel rows; staminal appendages entire in the outer whorl at least; flowers usually 5-merous (4-merous in Guyoniarupicola) calyx-lobes always persistent; hypanthium glabrous or with glandular hairs, rarely (Guyoniapygmaea) with simple eglandular hairs	14
14	Stems thick and fleshy, winged, erect; hypanthium with prominent longitudinal nerves; inflorescence an elongate cyme (raceme) with two well-developed bracts under each flower; plant almost glabrous except the ciliate leaves and calyx	Anaheterotis
–	Stems slender, usually not winged, creeping or more rarely erect; hypanthium with nerves hardly distinct; inflorescence not as above, usually with very small bracts, often 1-flowered; plant glabrous to densely hairy	Guyonia