Phylum: Magnoliophyta - Class: Equisetopsida - Order: Geraniales - Family: Geraniaceae
This annual or sometimes biennial member of the (wild) Geranium family displays a characteristic that is seen to some extent in most members of its genus: when its grows in dry exposed places, such as in crevices in walls and stone bridges, the leaves and stems turn red during dry weather.
Herb Robert can grow up to 40cm tall, producing usually pink but occasionally white five-petalled flowers typically 1 to 1.5cm across.
The three- or five-lobed hairy stalked leaves of Geranium robertianum are deeply dissected; when crushed they give off a somewhat spicy and unpleasant odour. The branching stems are also hairy and, like the leaves, gradually turn red, generally beginning with those nearest to the base.
Fruits (seed capsules) of Herb Robert are beaked, ridged and hairy; they also turn bright red.
Geranium robertianum is very common throughout Britain and Ireland, and it is found also in many mainland European countries, including Slovenia. Its natural range extends down to northern Africa and across into western Asia. Elsewhere in the temperate zone, including the Americas, Herb Robert is an introduced but now naturalised species, and in some places this plant is now considered to be a noxious invasive weed.
Herb Robert grows in hedgerows and on woodland edges, on wasteland and in the margins of crop fields; it is also very good at colonising the stony verges and central reservations of motorways. There is even a form, Geranium robertianum ssp. maritimum, which grows in sandy gravel along the coastal shoreline.
In Britain and Ireland Herb Robert can usually be seen in bloom from April until November, and in very sheltered locations we can often find flowers throughout the year unless we have a very harsh winter.
Herb Robert flowers are generally at their best during July and August, but the bright red seed capsules add a splash of colour to hedgerows in the autumn when few wildflowers are blooming.
Geranium, the genus name, comes from the Greek noun geranos, meaning Crane (birds of the group of species known as the Gruidae). It is a reference to the beak-like fruit (seed capsule) which is reminiscent of the long beak of a Crane. As for the specific epithet robertianum, which apparently honours someone with the name (probably the surname) Robert, we have not been able to pinpoint for certain the individual after whom Herb Robert is named. It is reputed to be Saint Robert, a French monk who in about 1000 AD was using this plant to treat and cure people with various diseases. Another possibility is that it is simply a corruption of ruber, which means red.
Some people eat the fresh leaves of Herb Robert in salads; and in the past both the leaves and the flowers have been used to make tea. When crushed the fresh leaves smell like burning spices or, some say, tyre rubber, and when rubbed on the skin it is said to act as a mosquito repellent. This plant has garnered many uses in herbalism, too, including for treating toothache and nosebleeds, and for covering wounds to aid their healing - rather as for example Marsh Woundwort plants were. Please note that it is essential to seek expert advice before using any plants medicinally.
Shining Cranesbill Geranium lucidum is a less hairy plant with smaller and usually less abundant flowers.
The Herb Robert plants shown on this page were photographed in West Wales and in The Burren, Ireland, during June.