1 | Perennial plants with tough, creeping rhizomes |
1' | Annual plants |
2 | Plants always monoecious, parts of it with few stinging hairs (less than 10 per internode or adaxial leaf surface in upper leaves); male inflorescence branches at lower nodes more or less equalling petioles |
2' | Plants mostly dioecious, densely covered with stinging hairs throughout; male inflorescence branches at lower nodes much longer than petioles |
3 | Female inflorescence a pedunculate, dense, globose capitulum |
3' | Female inflorescence not dense or globose |
4 | Male inflorescence a condensed axillary spike or cluster, much shorter than the subtending leaf, with inconspicuous rhachis |
4' | Male inflorescence elongate, caudate, much longer than the subtending leaf, with a conspicuous, membranous, flattened rhachis |