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Genus: Erodium

Erodium Species in
Erodium
Family: Geraniaceae

Approximately 60 species of annuals, biennials, perennials and subshrubs, widely distributed round the Mediterranean and eastward across temperate Asia as far as India, Australasia, North and South America with a major concentration in North Africa. Closely related to Geranium (and formerly included in it), but differing in having only five fertile stamens (and five infertile staminodes) and in the spiral twisting of the ripe seed-awns. The leaves of most species are opposite, though often crowded together so as to form a basal rosette; usually pinnate to pinnatifid and hairy. The flowers, in an umbel, are almost regular except that the upper two of the five petals may have a basal colour-blotch. The five seeds are contained, usually singly, in a structure (mericarp) consisting of a non-dehiscent carpel with a long awn, and these are joined together to form a beak, (hence the popular name stork,sbill). On ripening they separate from the base upwards, and with changing humidity the awns twist into a spiral, driving the seeds into the ground. Some species are dioecious.

Uses

The hardier species are valuable in the rock garden or raised bed, both for their foliage and their flowers. Of the slightly tender species a few are sufficiently small and neat to be appropriate for the alpine house. Sunny positions are required and well drained, ideally limey soil though this is not essential. Propagation by seed, but there is a tendency to hybridisation under garden conditions. They can also be propagated by basal cuttings in spring or summer and division in autumn or early spring. (Among the diagnostic features are the presence or absence of a leafy stem above the basal leaves (caulescent or acaulescent) and the presence or absence of very small (intercalary) leaflets alternating with the main ones. The term pinnate is used here though the secondary divisions may be pinnatifid or pinnatisect rather than strictly pinnate. Leaf-measurements exclude the stalk. The number of flowers (e.g. two to eight) means per inflorescence, but commonly they open consecutively over a long period from spring until autumn).