1. Leaves compound.
2. Leaves alternate or basal; carpels 5.
3. Leaves mostly 2–3 times compound, the ultimate leaflets pinnate; umbels normally 2 or more in an inflorescence.
3. Leaves palmately once compound; umbels solitary.
2. Leaves in 1 whorl, once-palmately compound; carpels 2 or 3.
1. Leaves simple, at most palmately lobed.
4. Petioles and main veins of leaf prickly.
4. Petioles and leaf veins not prickly.
5. Plants deciduous trees with thick, prickly twigs.
5. Plants lacking prickles, either small delicate unarmed herbs or evergreen vines.
6. Plants small, delicate glabrous wetland herbs.
6. Plants evergreen woody vines with sparse stellate pubescence.