Creeping oxalis or Yellow Wood Sorrel is found worldwide and is naturalised in Queensland.
Its features are variable and 8 subspecies, forms and varieties have been described but they
are now all regarded as synonyms.
The perennial herbs have fibrous roots and sometimes a short taproot.
The much branched 30 to 50 cm long stems can be prostrate or erect.
Creeping stems may root at the nodes.
Stems have a few to dense spreading hairs.
Alternately arranged leaves are on a smooth or hairy petiole up to 8 cm long.
The tiny stipules, 2 mm long that are fused to the petiole base almost always have short hairs on the edge.
Leaves have 3 obcordate (inverted heart-shaped) leaflets directly attached to the top of the petiole.
Leaflets are around 10 to 20 mm long.
They have 2 rounded lobes separated by a narow notch extending up to a third of the way to the base.
There are usually fine hairs at least on the lower surface.
The green, reddish or purple blades fold up in poor light.
Axillary inflorescences have 1 to 6 or 7 flowers at or near the end of a stalk (peduncle).
The smooth or hairy peduncles are up to 8 cm long and each flower is on a pedicel up to 1.5 cm long.
There are 2 to a few tiny hairy bracts on the inflorescence.
Each flower has 5 free sepals up to 5 mm long with hairs.
The 5 yellow petals are fused into a funnel-shaped corolla up to 1 cm long.
The 10 stamens are in 2 whorls with the longer inner 5 being around 5 mm long.
The hairy superior ovary, of 5 carpels has 5 locules each with numerous ovules.
There are 5 hairy styles around 5 mm long.
The fruit are narrow cylindrical capsules with a pointed tip.
Commonly around 2 cm long and only a few mms thick they have dense hairs on the outer surface.
The flattened reddish-brown seeds have a very rough ridged surface.