| 1 | Dioecious; tepals of female flowers absent |
| 1' | Monoecious; tepals of female flowers present (3-5 per flower) |
| 2 | Plants armed with axillary spines |
| 2' | Plants unarmed |
| 3 | Leaves strongly emarginate or bilobed at apex |
| 3' | Leaves neither strongly emarginate nor bilobed at apex |
| 4 | Tepals of female flowers 3; stamens 2-3 |
| 4' | Tepals of female flowers 5; stamens 5 |
| 5 | Terminal inflorescence 5-20(-25) cm long; tepals of female flowers equal; utricle roughly wrinkled or rugulose, at least above |
| 5' | Terminal inflorescence often exceeding 30 cm, massive; tepals of female flowers unequal, the inner shorter than the outer; utricle smooth or rugulose |
| 6 | Bracts usually 3.5 mm or longer, definitely exceeding the tepals; seeds reddish-brown or black |
| 6' | Bracts shorter than 3.5 mm, shorter than the tepals; seeds white, tawny, reddish-brown or black |
