| 1. Leaf blade round-peltate |
| |
| 2. Flowers long-pedicelled; umbels open |
| H. umbellata |
| 2' Flowers ± sessile; umbels small, head-like, in an interrupted, simple or forked spike |
| H. verticillata |
| 1' Leaf blade round-reniform, not peltate |
| |
| 3. Plant ± aquatic; flower, fruit pedicelled |
| H. ranunculoides |
| 3' Plant terrestrial; flower, fruit ± sessile |
| |
| 4. Plant hairy; flowers 1020 per umbel, subsessile |
| H. moschata |
| 4' Plant glabrous; flowers 310 per umbel, sessile |
| H. sibthorpioides
|