| 1 | Ovary with 5-16 (1-ovulate) carpels; aggregated fruit with several seeds |
| 1' | Ovary 1-locular, with 1 ovule; fruit with 1 seed |
| 2 | Stigmas 2, terminal |
| 2' | Stigma 1, sometimes lateral |
| 3 | Flowers sessile or subsessile (inflorescence a spike-like raceme); ovary and fruit with 4-6 retrorse apical hook-like awns (crushed plant with garlic or onion odor) |
| 3' | Flowers pedicellate (inflorescence a raceme); ovary without awns |
| 4 | Stem armed; fruit a samara. |
| 4' | Stem unarmed; fruit a drupe. |
| 5 | Annual, erect herbs or subshrubs; stamens 4; style elongate; tepals erect in fruit |
| 5' | Woody vines; stamens 8-12; style absent; tepals reflexed in fruit |
