| | 1. Plant hairy; older stems prostrate; receptacle in fruit 6–8 mm, reflexed |
| C. obtusifolia |
| | 1' Plant glabrous; older stems ascending to erect; receptacle in fruit < 6 mm or 6–10 mm and spreading to ascending |
| |
| | 2. Flowers solitary in leaf axils; receptacle reflexed in fruit |
| C. brevipes |
| | 2' Flowers in terminal racemes, sometimes also solitary in leaf axils; receptacle spreading to ascending in fruit |
| |
| | 3. Stem branched generally from base; petals 1.8–2.2 mm; receptacle in fruit 0.3–0.8 mm |
| C. parviflora |
| | 3' Stem branched generally from upper nodes; petals 3.5–7 mm; receptacle in fruit 6–10 mm |
| C. plocasperma
|