- Name also: Black Meddick, Black Hay, Hop Clover
- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Annual or biennial herb.
- Height: 10–60 cm (4–25 in.). Stem limp–ascending, hairy.
- Flower: Corolla zygomorphic, yellow, 2–3 mm (0.08–0.12 in.) long, fused at base. Petals 5; the upstanding the ‘standard’, the lateral two the ‘wings’, the lower two united to form the ‘keel’, overall shape of corolla being butterfly-like, dropping. Calyx 5-lobed. Stamens 10. A single carpel. Inflorescence an axillary, long-stalked, globose–elongated, dense raceme.
- Leaves: Alternate, stalked, stipulate. Blade with 3 leaflets, terminal leaflet stalked. Leaflets obovate, with notched tips, often sharp-pointed, tip with toothed margins. Stipules shortly united with stalks.
- Fruit: 1.5–3 mm (0.06–0.12 in.) long, kidney-shaped, coiled, net-veined, glabrous–with glandular hairs, brownish black, 1-seeded, indehiscent pod (legume).
- Habitat: Lawns, roadsides, railway yards, harbours, waste ground, shores.
- Flowering time: June–September.
Black medick has arrived and settled into Finland relatively recently. It is widely distributed but fragmented throughout southern and central Finland around harbours, on lawns, by railways and on waste ground. Stands in coastal towns are mainly from the ballast soil that sailing boats carried when they needed more weight. It has travelled to many important towns and crossroads with soldiers and their provisions and landed on lawns with uncleaned hayseed and around railways and warehouses with imported grain.
At first glance black medick looks like clover, especially lesser hop trefoil (Trifolium dubium) and hop trefoil (Trifolium campestre). Both have small yellow flowers and three leaflets, but there are also differences: black medick’s corolla falls as the seeds ripen while clover corollas remain after they wither. Also, black medick’s pod is curved or twisting while clover pods are basically straight. Compared to other members of its genus, black medick’s pod is spineless, and very small. There are three variations of black medick in Finland which can be differentiated from each other according to the amount of glandular hairs they have.