| 1 | Densely bristly-hairy annual herb; corolla less than 10 mm; nutlets 4, glabrous | Trichodesma zeylanicum |
| 1 | Glabrous to sparsely bristly-hairy perennial herbs; corolla more than 10 mm; nutlet 1, tomentose | 2 |
| 2 | Stems ± glabrous; corolla white (rarely pinkish); lobes not spreading or reflexed | Trichodesma physaloides |
| 2 | Stems bristly-pubescent (sometimes only sparsely); corolla blue (sometimes pinkish); lobes spreading or reflexed | Trichodesma ambacense subsp. hockii |