Until the 1980s Danish Scurvygrass (Cochlearia danica) was found on coastal cliffs, sand dunes and sea-walls. Since then, it has become established on the central reservation of motorways, dual carriageways, verges adjacent to trunk roads and the grounds of motorway service stations.
Danish Scurvygrass image credit to Bob Osborne.
Description
It is a native, mat-forming herb with a requirement for salt – hence its migration from the coast to salt-treated roads. Interestingly, although this has happened in Northern Ireland, it hasn’t in Southern Ireland where grit is used instead of salt.
The flowers are mainly white, but tinged with mauve. They are the first of the scurvygrasses to appear in England in their natural habitats in January/February. They become visible en masse in the central reservation of motorways in late March and April when they form a carpet of glistening white flowers.
The ball-shaped fruits readily detach from the mats and bowl along the roads in the slip-stream of vehicles, thereby spreading the plant. In June and July, the masses of dry balls on the mat give the central reservations a silvery sheen.
Leaves are dark green, fleshy and ivy shaped.
Source: English Wild Flowers – A Seasonal Guide by Keith and Violetta Jones
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