Trifolium subterraneum

Scientific profile

Trifolium subterraneum is a native annual herb in the pea family. It is prostrate and hairy, with long-stalked, trifoliate leaves; the leaflets are obcordate, typically 1–2 cm wide, and resemble those of Oxalis. The inflorescences are axillary, stalked heads bearing a few fertile flowers and several sterile ones. After flowering, the pedicels reflex, pressing the developing fruiting head against the soil surface; the head may become partially buried, a distinctive self-burying behaviour that aids seed placement. The plant grows to around 10 cm tall, has broad leaves and a non-woody stem. It prefers full sunlight and dry, low-nutrient soils, and tolerates low levels of salinity. It shows a preference for warmer conditions. The root system forms arbuscular mycorrhizal associations. Seed mass averages about 6.4 mg. Flowering extends from May to September. In Great Britain the species is considered a native wild plant.