Pink shamrock, native to South America is widely naturalised along the coastal areas of S.E. Queensland where it is a minor weed.
It has 20 synonyms including Oxalis corymbosa, Oxalis debilis subsp. corymbosa and Oxalis debilis var. corymbosa.
The perennial herbs have a very short or no above ground stem with leaves and flowers growing from an underground bulb.
The ovoid to spherical bulbs are 1 to 3 cm long and covered in brown papery scales with long hairs.
The thick taproot has branched fibrous roots.
Up to 20 alternately arranged leaves are clustered at the base of the plant.
They have petioles, up to 25 or 30 cm long with scattered long simple hairs.
Attached to the base of most petioles are 2 pale membranous stipules.
Up to 12 mm long and 2 mm wide at the top they are fused to the petiole and taper towards the base.
The leaves are trifoliate with 3 leaflets on very short or no stalks (petiolules).
The obcordate (inverted heart-shape) leaflets can be up to around 4.5 cm long and 5 cm wide.
Leaflets have an apical notch up to one fifth of their length.
The notch can be narrow or up to 12 mm wide at the top.
There are short hairs (cilia) on the edges and there may be a few longer simple ones on both surfaces.
The edges and lower surface may have small orange dots of oxalate crystals (calli).
Inflorescences, from the bulb, are a peduncle with up to 15 flowers attached at or near the top (umbel-like).
The slightly hairy peduncles are up to 35 cm long holding the flowers above the leaves.
Each flower is on a pedicel 2 to 3 cm long with a few or no hairs.
At the top of the peduncle is a pair of hairy bracts a few mms long and each pedicel has 2 smaller hairy ones.
These may have orange calli on the tips.
The bisexual flowers have 5 sepals and petals.
The overlapping sepals, shortly joined at the base are up to 5 or 6 mm long.
They are green, have simple hairs and 2 orange calli at the tip.
The obovate petals form a funnel-shaped corolla up to 2 cm long.
Petals are pink to pale mauve (rarely white) with a bright green throat and purple veins.
The 10 stamens are in 2 whorls with the filament bases fused.
The outer 5 have smooth 3 mm long filaments and the inner 6 mm ones are hairy.
The anthers open through longitudinal slits.
The hairless superior ovary has 5 carpels and 5 locules each with up to 8 ovules in 1 or 2 vertical rows.
The 5 densely hairy styles are around 6 mm long.
Fruit capsules are rarely seen with reproduction being by the many bulbils that grow from the old bulbs.
The ovoid white bulbils are 5 to 10 mm long.