An evergreen shrub, with erect, half-woody branches, rarely seen more than 3 ft high. Leaves of a markedly glaucous hue, alternate, variable in length, but usually 3 to 5 in. long, pinnately decompound, the leaflets usually confined to the upper half, the ultimate subdivisions obovate, 1⁄8 to 1⁄2 in. long. Flowers 3⁄4 in. wide, arranged in terminal corymbs, rather dull yellow; the sepals and petals usually four, sometimes five; the stamens twice as many. Petals scoop-shaped with jagged edges. Fruit a usually four-celled capsule.
Rue is known best, of course, as a garden herb with an acrid taste, once used in domestic and especially rustic medicine for colic, hysteria, promoting perspiration, etc. Applied locally it is a powerful irritant. These properties are due to a volatile oil which permeates the leaves and younger parts of the plant. Given in too large doses it is dangerous, and produces symptoms of acrid narcotic poisoning. The species is a native of S.E. Europe. Owing no doubt to its medicinal properties it has been grown in gardens from time immemorial and has become widely naturalised in Southern Europe generally. It finds frequent mention in Shakespeare as ‘herb of grace’:
I’ll set a bank of rue, sour herb of grace.
– The gardener, in King Richard II.
It should find a place in all extensive shrub collections not only for its associations, but for its beauty also. When fully in flower the dark yellow blossoms contrast prettily with the glaucous foliage, and they continue to open from June onwards for some months. It is quite easily increased by cuttings, and will thrive all the better if lime or chalk be mixed with the soil where these are naturally absent.
cv. ‘Jackman’s Blue’. – Of compact, dwarf habit, with vividly blue-grey foliage. The original plant grew in the garden of Mr Greener, a part-time grower of nursery stock, who lived at Ottershaw, Surrey, and died in 1939. It was noticed by the late Rowland Jackman when he called to buy some plants, and from the cuttings given to him derives all the stock of this now much planted variety (Gard. Chron., Vol. 171 (1972), p. 29). It was put into commerce by Messrs Jackman shortly after the second world war.
cv. ‘Variegata’. – Leaves bordered with white.