Family Fabaceae > Subfamily Faboideae > Tribe Desmodieae.
Creeping tick-trefoil has 36 synonyms including Desmodium triflorum, Hedysarum triflorum and Meibomia triflor.
Widespread around the world in the Tropics and Subtropics their place of origin is uncertain.
They are a common weed in lawns but usually not seen due to their small size and often being mixed with clovers and similar plants.
They are a prostrate perennial herb a few cms high.
They have a taproot and above ground stolons.
Stolons are stems that run along the ground and root at the nodes.
They branch a lot and can produce dense mats up to 50 cm across.
Very young stems are greenish but soon become reddish-brown.
Old stems at the base may be slightly woody.
All stems have white hairs that are usually long and dense.
The alternate leaves are on a petiole up to around 14 mm long.
Beside the base are 2 usually hairy stipules from 2 to 15 mm long.
The triangular to lance-shaped stipules are up to 15 mm wide at the base.
Initially green they become brown and membranous with prominent veins.
The blades are trifoliate with 3 leaflets on a hairy midrib or rachis up to 5 mm long.
Each leaflet is on a petiolule around 2 mm long with a pair of tiny stipels at the base.
There are long white hairs on all parts.
Leaflets are mostly up to around 1 cm long and wide but can be more.
The terminal leaflet is larger and on a longer petiolule.
Leaflets are obovate, obcordate to almost round with a rounded or heart-shaped base.
The edge is smooth and there is often a notch at the tip and sometimes a mucro (tiny abrupt point).
Hairs on the lower surface lie along the blade and there may be a few on the upper surface.
Inflorescences are terminal and in the axils of the leaves near the stem ends.
They are racemes with a central axis holding up to 5 flowers but mostly 1 to 3.
Flowers are on a hairy pedicel around 5 or 6 mm long that gets longer on the fruit.
There are very hairy, 5 mm bracts at the base of the pedicels.
The calyx has 5 sepals with long hairs on the outer surface.
Their bases are fused for around 1 mm and the lobes are around 2 mm long.
The upper 2 lobes may be partly fused. They persist on the fruit.
The corolla, around 5 mm long has 5 petals in a typical pea flower shape.
The largest, the standard is almost round with a narrow tapering base.
The 2 wing petals enclose the 2 partly fused keel petals.
The standard and wings are mauve to pink.
The standard is darker at the base of the erect section and the wings are a deep purple on the edges.
There are 10 stamens with the filaments fused into a long tube with short free ends.
The upper stamen may be fused or free.
The long narrow superior ovary has a single locule with a few ovules.
It is covered in short hairs and has a style that bends at a right angle.
The fruit are commonly called pods but, but being constricted between the seeds are actually loments.
The slightly curved, flat loments are up to almost 20 mm long.
Each has up to 5 seeds with the loment constricted between the them.
This makes the lower suture notched or lobed and the upper straight.
The surface has small hairs with a hook at the tip.
When mature they separate into up to 5 segments each with 1 seed.
The yellow-brown round to kidney-shaped seeds have dark flecks on them.
J.F.
