File:Trifolium subterraneum habit2 - 10734390724.jpg

English: Introduced, cool-season, annual legume with a short taproot. Leaves have 3 leaflets, each hairy, heart-shaped and on stalks of equal length. Leaflets have variable white and brown markings that vary depending on variety and time of year. Flowerheads consist of clusters of 3-6 white (rarely pinkish), pea-like flowers. Depending on variety seedheads are either pushed into cracks or buried in the ground. Flowering is from spring to early summer. A native of Europe and the Mediterranean region, it is occasionally sown in drier, cooler areas on the coast and mostly naturalized on the central coast. Grows on moderately acid to neutral soils.

There are 3 distinct subspecies: 1) subterranean – suited to well-drained, slightly acid soils, 2) yanninicum - tolerates intermittent waterlogging and poorly drained conditions and

3) brachycalycinum - suited to neutral to alkaline soils. Fixes nitrogen and produces high quality feed from autumn to spring but can cause bloat. In the Hunter-Manning and Metropolitan areas it is used as both an annual forage crop and a pasture species. Often planted in a mix with white clover (in drier areas) but does not persist in many coastal areas. Requires medium to high soil fertility, particularly phosphorus, sulfur and molybdenum. Withstands close grazing. Grass needs to be well grazed in late summer to remove residues and aid the germination and growth of clover seedlings.