In a loosely defined Fabaceae family the Mimosa genus is in Subfamily Caesalpinioideae or Mimosoideae.
In a strictly defined Fabaceae family the Mimosa genus is in the Family Mimosaceae (Caesalpiniaceae).
This was the old classification and the one I use.
Plants of the World Online has 611 accepted species
Most are herbs or sub-shrubs with a few trees to 10 m high.
Herbs and sub-shrubs may be trailing, prostrate with semi-erect tips or scramble over other vegetation.
Shrubs can form dense thickets.
Prickles are common on the stems and there may be various types of hairs.
The alternate leaves are typically bi-pinnate but may apear to be digitate.
This happens when the midrib is very short and the pinnae are all attached to the end of the petiole.
At the base of the petiole is a pair of stipules that usually fall.
There is a pulvinus at the petiole base and the midrib may have prickles.
The blades have 1 to many pairs of opposite branches or pinnae.
Leaflets on the pinnae have a pulvinus that often has hairs on it.
Axillary inflorescences, on a peduncle may be heads or spikes that are solitary or clustered.
The flowers have no pedicel but do have small bracteoles at their base.
The usually small bisexual or male flowers have parts in 4’s or 5’s (3 – 6).
The usually very small calyx has a tubular base with 4 (3 – 6) lobes or teeth.
The white or pink corolla has a tubular base with 4 (3 – 6) lobes no longer than the tube.
The stamens are equal in number to the petals or double that number.
The superior ovary has 2 to many ovules.
The fruit are straight, curved or coiled legumes (pods).
The oblong or linear pods are flattened and usually have bristles or prickles.
When mature the upper and lower sutures remain intact.
Between the sutures the pods break into segments each with 1 seed.
The round or elliptic seeds are flattened.
J.F.
