1 | Leaf-rachis with a straight prickle at the junction of each pair of pinnae (originally from tropical South America) |
1' | Leaf-rachis without a straight prickle at the junction of the pinnae, sometimes unarmed |
2 | Small trees, introduced |
2' | Armed (or unarmed) herbs, subshrubs or scandent shrubs |
3 | Juvenile branches and leaves covered with stellate hairs (originally from SE Brazil, locally introduced) |
3' | Juvenile branches and leaves without stellate hairs (originally from S Brazil and NE Argentina) |
4 | Leaves without prickles on petiole and rachis; pinnae 1 or 2 pairs, subdigitate (pan-tropical, of South American origin) |
4' | Leaves ± prickly on petiole and rachis (except for cultivar M. diplotricha var. inermis); pinnae 4-7 pairs evenly arranged along the rachis (originally from tropical America) |