- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Perennial herb.
- Height: 20–50 cm (8–20 in.). Stem limp–almost erect, sparsely branched, glabrous–upper part hairy, grooved.
- Flower: Corolla irregular (zygomorphic), white–reddish, finally brown, 5–12 mm (0.2–0.48 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. Calyx 5-lobed, almost glabrous. Stamens 10. A single carpel. Inflorescence long-stalked, densely globose.
- Leaves: Alternate, stalked, stipulate. Blade with 3 leaflets; leaflets ovate, blunt-tipped, uneven, with finely toothed margins, without spots. Stipules mainly united with stalks.
- Fruit: Indehiscent pod, remains inside calyx.
- Habitat: Fields, meadows, roadsides, banks, waste ground, meadows. Also a fodder plant.
- Flowering time: July–August.
Alsike clover is named after the parish of Alsike in Sweden, where Carl von Linné studied the species. He thought that it was a new hybrid between white clover (T. repens) and red clover (T. pratense), which is where the plant’s species name hybridum comes from. However, although alsike clover shares many characteristics of white and red clover, it is an independent species. Happily there are clear differences with regards to both structure and ecology. White clover differs from alsike clover in its growing form; white clover is creeping while alsike clover is more erect. Red clover clearly differs with respect to its clearly hairy calyx, and it (and often also white clover) usually has a white blotch on the leaflets that alsike clover lacks. Alsike clover demands a damper habitat than red clover and can stand periodic flooding. It also flowers slightly later than red and white clover. Like many other clovers it must be pollinated by insects. Alsike clover’s calyx-tube is however shorter than e.g. red clover, and it is easier to pollinate because insects with short proboscises can also reach the back of the flower. The plant usually produces and abundance of seeds. They can germinate as soon as they ripen, but it is typical of clovers that the hard-shelled seeds only sprout the following spring.
Alsike clover’s pollination biology and seed production have been studied with particular interest because it is a valued fodder plant. Like other Pea family species its rootstock contains rhizobium bacteria. These long-lasting bacteria are able to fix nitrogen from the atmosphere in the ground for the use of the plants, so alsike clover fertilizes its own habitat. In return the bacteria receive assimilation products as nutrition.