Subfamily Mimosoideae
Description: Trees, shrubs or rarely vines or herbs.
Leaves mostly bipinnate or reduced to phyllodes; petioles, upper margin of phyllodes and rachis often with jugary or interjugary glands; stipules, if present, small and caducous or sometimes prominent and spinose.
Inflorescences racemes, spikes or heads; individual flowers usually small and often clustered into a showy inflorescence; bracteoles small or absent. Flowers usually actinomorphic. Sepals usually fused basally into a tube, lobes usually valvate. Petals free or fused below into a tube. Stamens mostly 10 or numerous; filaments usually free, commonly coloured and long-exserted and collectively forming the most conspicuous part of inflorescence; anthers versatile, opening by longitudinal slits.
Fruit usually a pod, ± elongate, often compressed; seeds sometimes arillate.
Distribution and occurrence: World: c. 60 gen., >3000 spp., widespread, especially in trop. and subtrop. regions. Aust.: c. 17 gen., >700 spp., all States.
Many genera are cultivated as ornamentals. Some species are the source of timber, gums or bark (used in the tanning process). This subfamily is sometimes treated as the family Mimosaceae.
Taxa not yet included in identification key
Desmanthus,
Vachellia
| | Key to the genera | |
| 1 | Mature plants with phyllodes, 'leaves' appearing simple. | Acacia |
| Leaves bipinnate. | 2 |
| 2 | Majority of leaflets >12 mm wide, usually <12 leaflets per pinna; plants neither spiny nor bristly. | 3 |
| Leaflets <12 mm wide and either numerous per pinna, or if c. 12 then plants spiny or bristly.
Back to 1 | 4 |
| 3 | Leaves with leaflets alternate along the pinnae rachis and mostly with 2–4 pairs of pinnae; pods ± papery. | Pararchidendron |
| Leaves either with leaflets opposite along the pinnae rachis (pinnae 1–5 pairs), or if leaflets alternate then leaves with only 1 or 1 pair of pinnae; pods leathery to woody.
Back to 2 | Archidendron |
| 4 | Stamens usually 5 or 10. | 5 |
| Stamens numerous, >10 per flower.
Back to 2 | 8 |
| 5 | Stems armed with spines or prickles. | 6 |
| Stems neither spinose nor prickly.
Back to 4 | 7 |
| 6 | Spines straight, >10 mm long; petiole and rachis of mature leaves glabrous; flowers greenish yellow; pods ± moniliform, not bristly, >5 cm long. | Prosopis |
| Prickles recurved, <5 mm long; petiole and rachis of leaves hairy; flowers pink; pods not moniliform, bristly, <3 cm long.
Back to 5 | Mimosa |
| 7 | Shrubs or trees; stipules absent. | Leucaena |
| Prostrate herbs or subshrubs, <50 cm high; stipules persistent, 4–9 mm long.
Back to 5 | Neptunia |
| 8 | Stamens free, usually <8 mm long; flowers in globose heads. | Acacia |
| Stamens united into a tube at base, stamens >10 mm long; flowers in cylindrical racemes.
Back to 4 | Paraserianthes |
|
