Bithynian vetch: a well-travelled leguminous plant

Vicia bithynica, commonly known as Bithynian vetch, is a perennial leguminous species belonging to the Fabaceae family, characterised by its climbing stems, which can reach about 60 centimetres above ground.

The leaves are arranged alternately along the stem and can reach up to nine centimetres in length. They have two to three pairs of leaflets and end in branched tendrils, which aid the plant in anchoring itself and “climbing”. Its petioles are about two centimetres long with a large, ovate, dentate stipule at the base.

The flowers are generally arranged in pairs — although sometimes solitary — on long peduncles, with about five centimetres, branching from the leaf axils. The petals are purple and white, measuring about two centimetres in length, with a typical legume structure, and have ten stamens and one style.

The fruit of the Bithynian vetch is a hairy pod, similar to its “cousin” the pea, measuring up to five centimetres in length and with four and eight seeds. The species has fourteen chromosomes.

A passport full of stamps

With an impressive capacity to adapt, the Bithynian vetch occurs in woodland, scrubland, calcareous grassland and agricultural fields.

Its distribution extends over much of the Mediterranean region, also reaching north Scandinavia and Great Britain. There are, also, isolated populations in the Azores, the United States, Australia and New Zealand.

In Portugal, it is a native species on the mainland and in the Azores, and is absent from the Madeira archipelago.

The Bithynian vetch, considered as an endangered species, is classified as “Vulnerable” in Portugal.

Did you know that…

• The Bithynian vetch is of great ecological and agricultural importance, notable among other traits for its ability to fix atmospheric nitrogen in the soil, a characteristic common to leguminous plants. This process contributes significantly to soil fertility, favouring the development of other plant species and promoting more sustainable agricultural practices.
• The term “bithynica” refers to Bithynia, an ancient region in what is now Turkey, suggesting the possible geographical origin or historical distribution of this leguminous plant.
•  In Great Britain, at the northern edge of its distribution, the Bithynian vetch is most often found on coastal cliffs, seashores, and old railway lines.