Cracca atropurpurea (Desf.) Godr. & Gren.
Vicia atropurpurea Desf.
Common Name: Purple Vetch
Vicia benghalensis is an annual or short-lived perennial plant with robust stems; it grows up to 60cm tall[
The plant is cultivated, especially in USA and Australia, as a green manure and a cover crop to protect the soil from erosion; there are several named varieties[
The plant can become a weed of cultivated fields.[
The seeds contain the anti-nutritional compound L-canavanine, a competitive inhibitor of arginine decarboxylase. This is removed by soaking the seeds in water prior to cooking and discarding the soak water[
Mediterranean - Portugal to Greece, Macaronesia, Morocco, Algeria and Tunisia
Field margins, waste places etc in Britain[
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Vicia benghalensis is a plant of Mediterranean climates, where it is found at elevations up to 2,800 metres. It can tolerate a range of climates from semi-arid, through moist temperate and subtropical. It grows best in areas where annual daytime temperatures are within the range 18 - 24°c, but can tolerate 8 - 30°c[
]. When dormant, the plant can survive temperatures down to about -1°c, but young growth can be severely damaged at -1°c[
]. It prefers a mean annual rainfall in the range 700 - 900mm, but tolerates 310 - 1,660mm[
Species in this genus generally succeed in any well-drained soil in a sunny position if the soil is reliably moist throughout the growing season, otherwise they are best grown in semi-shade[
]. Prefers a pH in the range 6.5 - 7, tolerating 4.5 - 8.2[
This species is closely related to Vicia villosa[
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[
A good green manure plant, it is fairly fast growing, an effective weed suppresser, fixes nitrogen and makes a reasonable bulk[
]. It is also grown as a cover crop to protect the soil from erosion[
A turquoise-green dye is obtained from the flowers[
Seed - sow in situ in spring or autumn. The seed has a hard seedcoat and may benefit from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing.