Purple milk-vetch Astragalus danicus

This rich bluish-purple flower is actually related to the pea.

It is a low-growing, hairy herb. Purple milk-vetch's flowers are gathered densely and compactly so as to look like a single bloom. Once these have died back, swollen pea-like seed pods - dark brown and sprinkled with obvious white hairs - take their place. Its leaves are typically pinnate (resembling a feather with pairs running in parallel long the stem) and are between three and seven centimetres in length.

Distribution

Purple milk-vetch has inland populations in southern England in Gloucestershire, Wiltshire and on the Brecklands of Norfolk and Suffolk. Further north the populations are mainly towards the eastern side of England, east Midlands, Lincolnshire and Yorkshire Wolds, as well as coastal grasslands in the north-east of England and Scotland. It is absent from Wales and Northern Ireland. An isolated population occurs on Aran Islands off the west coast of Ireland.

Habitat

Its main habitats are species-rich short, dry and infertile calcareous grassland, on both limestone and chalk. The plant is also found on coastal sand-dunes and in the Brecks on inland calcareous sands. It appears to be physically rather than chemically restricted to calcareous soils and will grow on moderately acid sands/gravels as long as competition from other species is kept low, primarily by adequate grazing and maintenance of low soil nutrient status. In Scotland purple milk-vetch is also present on old red-sandstone sea cliffs and machair grassland.

Status

Classified as ‘Endangered’ and is included as a species “of principal importance for the purpose of conserving biodiversity” under Section 41 (England) of the Natural Environment and Rural Communities Act 2006.

Key threats

Purple milk-vetch has declined on the chalk grasslands in southern England and limestone in north-east England due to the destruction of habitat through agricultural improvement and lack of suitable grazing management. Additionally, nitrogen from drifting crop spray or atmospheric deposition is also thought to affect this plant.

Best time to see

June and July when in flower.