 | If there are two stigmas and pistillate spikes are 4-6 mm wide
 | C. aquatilis |
|
| Else If sheaths pubescent
| C. atherodes |
|
| Else If pistillate spikes on filiform stalks
| C. pseudocyperus |
|
| Else If perigynium is pubescent
| If leaves < 2.2 mm wide and involute
 | C. lasiocarpa |
|
| Else If leaves 2-3 mm wide and flat
| C. pellita |
|
|
| Else If style is persistent and S shaped
| If adaxial leaf surface with papillae
| C. rostrata |
|
| Else If adaxial leaf surface without papillae
| C. utriculata |
|
|
| Else If beak 0.5-1.6 mm long and scale length variable
| C. lacustris |
|
| Else If beak 2-3 mm long
| C. laeviconica |
|