This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Hare's Foot Trefoil is unknown in any ancient deposits in Britain. A member of the flora of the North Temperate Zone it is found in Europe, N. Africa, N. and W. Asia, and is introduced in America. In Great Britain it is found in ninety-four of the vice-counties. It is common also in Ireland and the Channel Islands.
The occurrence of Hare's Foot Trefoil, whether wild or otherwise, is an indication of dry soil. It grows in dry pastures inland, or on barren stony ground, in all cases requiring a sandy subsoil. It is also a common plant on waste ground, being often introduced into quarries with fodder, and upon waste ground by building operations through the transfer of materials by railway, etc.
This handsome plant is tall and erect, having a silvery, downy appearance, with a slender trefoil habit. It is branched with short, spreading, alternate, ascending branches. There are three oblong leaflets.
The flowers are in egg-shaped or rounded, terminal, soft, rosy-white heads which lengthen, with soft, hairy calyx-teeth much longer than the corolla, giving the head a soft feathery appearance. The corolla is papilionaceous, shorter than the calyx, and hidden amongst the bristle-like teeth. The inversely egg-shaped fruits are enclosed by the calyx and retained in the head when ripe.
Hare's Foot Trefoil is usually about 1 ft. high. The flowers may be sought in July and August. The plant is annual and increased by seed.
Though the flowers are very small they are visited by a variety of insects. The stamens are united as in other types of papilionaceous flowers. Hare's Foot Trefoil is visited by Hymenoptera (Apidae), Apis mellifica, Bombus rajellus, B. lapidarius, Cilissa leporina, Andrena xanthura, Halictus zonulus, H. quadricinctus, Osmia calmentaria, Megachile maritima; Sphegidae, Psammophila affinis; Lepidoptera, Small Skipper (Adopaea thaumas).
Hare's Foot Trefoil (Trifolium Arvense, L.)
The outer perianth is feathery and persistent, and winged, assisting the fruits to some extent to disperse themselves by aid of the wind, or they lie in the heads and the seeds germinate on the ground.
Hare's Foot Trefoil is most at home on a sand soil, and is thus a sand plant. It also grows on rocky, stony ground, Precambrian and older granitic and metamorphic rocks.
No insect or fungal pests infest this plant.
This plant has the specific name arvense because it is associated largely with arable land.
It is called Hare's-foot Clover, Dogs-and-cats, Hare's Foot.
Essential Specific Characters:79. Trifolium arvense, L. - Stem erect, branched, leaflets linear, obovate, terminal flowers in cylindrical heads, softly hairy, pink, small, calyx teeth subulate, setaceous, longer than corolla.