- Latin synonym: Coronilla varia
- Name also: Purple Crown Vetch, Crownvetch, Crown-vetch
- Family: Pea Family – Fabaceae (Leguminosae)
- Growing form: Perennial herb.
- Height: 40–120 cm (15–50 in.). Stem limp–ascending, erect-branched, glabrous.
- Flower: Corolla zygomorphic, reddish, 10–15 mm (0.4–0.6 in.) long. 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. Standard pink, dark-veined, wings and keel white, tip of keel dark purple. Calyx 5-lobed. Stamens 10. A single carpel. Inflorescence in axils, long-stalked, spherical, 5–20-flowered umbel.
- Leaves: Alternate, short-stalked, stipulate. Blade pinnate, 5–10 pairs, with terminal leaflet. Leaflets elliptic, with entire margins.
- Fruit: 3–5 cm (1.2–2.0 in.) long, spreading, 4-edged, indehiscent, pod (legume) breaking but not constricted between seeds.
- Habitat: Sunny meadows and meadows, roadsides, dumps, gardens.
- Flowering time: July–August.
Crown vetch has been included among Finnish flora for a relatively short time. It used to be listed as a cultural alien just over the border in Karelia, but it has since made itself at home in southern Finland too. The species’ natural area of distribution is across Europe, North Africa and Asia. In the USA and Canada it is commonly used to counteract erosion, to improve the land and as an ornamental thanks to its nature as a deep-rooting, fast spreading plant that fixes its own nitrogen from the air. Unfortunately these same properties make it a fierce competitor which takes over land from other native plants. It has become a nuisance in many places and there have been attempts to eradicate it by digging it up by the roots, burning it and poisoning it. In Finland it is at least so far a relatively rare oddity in open and sunny sand and moraine environments. Crown vetch can also sometimes be seen in gardens, where it thrives in the thinnest, sun-baked soils, rewarding its carer with long-lasting pale reddish violet flowers.
Crown vetch’s pollination biology is unique: the stamens’ anthers open early and pollen becomes packed into the tip of the keel, from where it is prevented from flowing backwards by thickly-downed filaments. When a large insect lands on the keel and wings they bend downwards, but the androecium-tube resists movement and pushes the pollen plug upwards, just like toothpaste from a tube, against the back of the insect. When the insect then visits another flower slightly later, whose pistil is extended in anticipation, the part that has the sticky pollen on it touches the tip of the pistil, the stigma.
NOT TRANSLATED YET. Name also Serradella. Meillä satunnainen peltolinnunjalka muistuttaa jonkin verran kirjonivelvirnaa. Lehdykkäpareja on paljon ja lehdet ovat päätölehdykällisiä. Kukat molemmilla ovat yleensä vaaleanpunaisia ja kukinnot pallomaisia sarjoja, peltolinnunjalalla kukkia on kuitenkin vähemmän (2–5). Hedelmävaiheessa eron huomaa parhaiten: peltolinnunjalan palko on papujen välistä kuroutunut (papujen lukumäärä on helposti luettavissa), kirjonivelvirnan palko on kypsänäkin sileä ja 4-särmäinen.