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Geranium macrorrhizum (rock crane's-bill)

Geranium macrorrhizum is an aromatic perennial with attractive soft leaves and pink or purplish flowers, and provides good ground cover.

Pink-purple flowers of rock crane's-bill

Geranium macrorrhizum in Osaka Prefectural Flower Garden, Osaka, Japan (Photo: Wikimedia Commons, licensed under CC by 3.0)

Species information

Scientific name: 

Geranium macrorrhizum L.

Common name: 

rock crane's-bill, hardy geranium, wild geranium

Conservation status: 

Not considered to be threatened, but not yet evaluated according to IUCN Red List criteria.

Habitat: 

Rocky places on limestone, often in shade.

Key Uses: 

Ornamental.

Known hazards: 

None.

Taxonomy

Subclass: 
Superorder: 
Rosanae
Order: 
Geraniales
Family: 
Geraniaceae
Genus: Geranium

About this species

An easily grown and attractive perennial, Geranium macrorrhizum has a thick, succulent rhizome (underground stem) and soft, deeply divided, aromatic leaves. The flowers are produced in the spring and summer, and have a reddish calyx and pink, reddish-purple or rarely white petals. The specific epithet macrorrhizum refers to its large rhizome.

Genus: 
Geranium

Discover more

Geography and distribution

Native to Europe (from France to Greece and Romania), where it is found in the southern Alps, Apennines, Balkan Peninsula and Carpathians. It is occasionally found as a garden escape in Great Britain and elsewhere.

Description

The rhizome (underground stem) is thick and fleshy, and creeping when reaching the surface. The leaves are aromatic, soft and minutely velvety, around 7 cm across, deeply divided into 5-7 lobes and are borne on stalks of around 10 cm long. The leaves become reddish in the autumn. The flowers are borne on branching stems of up to 30 cm tall. Each flower is 1.5-2 cm across, with five rounded, pinkish-purple, pink or rarely white petals and a reddish calyx.

The cultivar Geranium macrorrhizum ‘Album’ has white flowers with a reddish calyx. It was first found in the Rhodope Mountains in Bulgaria, but is now naturalised elsewhere (including in Great Britain), having escaped from cultivation. G. macrorrhizum ‘Bevan’s Variety’ has large, bright reddish flowers, while G. macrorrhizum ‘Variegatum’ has irregular cream markings on the leaves. There is also a variety called 'White-Ness', sometimes cultivated, with a green calyx and white petals.

Illustration from Curtis's Botanical Magazine

Illustration of Geranium macrorrhizum from Curtis's Botanical Magazine by J. Curtis.

Curtis’s Botanical Magazine (Editor: Martyn Rix) provides an international forum of particular interest to botanists and horticulturists, plant ecologists and those with a special interest in botanical illustration.

Now well over 200 years old, the Magazine is the longest running botanical periodical featuring colour illustrations of plants. Each four-part volume contains 24 plant portraits reproduced from watercolour originals by leading international botanical artists. Detailed but accessible articles combine horticultural and botanical information, history, conservation and economic uses of the plants described.

Published for the Royal Botanic Gardens, Kew by Blackwell Publishing.

Find out more about Curtis’s Botanical Magazine

Threats and conservation

Geranium macrorrhizum is common in rocky woods in mountains, and is not considered to be threatened.

Uses

A very useful ornamental for ground cover under shrubs, or for other dry, shady places where little else will survive. Geranium macrorrhizum thrives in dry or moist places, in sun or shade, and is excellent for attracting bees. It can become slightly invasive in some gardens, but is easily kept in check by cutting through the rhizomes using a spade.

In Bulgaria, G. macrorrhizum is widely grown as a cultural symbol associated with health and good luck.

It is the source of Zdravetz oil, which is used in traditional medicine as both a stimulant and as a carminative, and is also used as a fixative in perfumery. Zdravetz is a Bulgarian word meaning ‘health’. The essential oils found in both the aerial parts and rhizomes have been shown to have antibacterial activity.

Millennium Seed Bank: Seed storage

Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

Number of seed collections stored in the Millennium Seed Bank: Two

Cultivation

Easily grown in dry locations in partial shade. In cooler parts of northern Europe it performs best in full sun. Geranium macrorrhizum can be propagated easily by dividing and replanting the rhizomes in autumn or spring.

This species at Kew

Geranium macrorrhizum can be seen growing alongside the Rock Garden and in the Queen’s Garden (adjacent to Kew Palace).

Kew at the RHS Chelsea Flower Show 2011

In 2011, Kew partnered with The Times to produce a show garden to showcase the significance of plants to science and society.

The garden, designed by Chelsea gold medallist Marcus Barnett, featured species chosen to demonstrate both beauty and utility, including medicinal, commercial, and industrial uses to underline the fact that plants are invaluable to our everyday lives – without them, none of us could live on this planet; they produce our food, clothing and the air that we breathe.

There were several Geranium species - and cultivars of Geranium species - featuring in Kew’s garden at Chelsea, which was awarded a Silver Medal. A cultivar is a cultivated variant of a species, which is often called a ‘variety’ in the horticultural trade. Cultivars usually have characteristics that make them more desirable to growers, for example a carrot that is sweeter than its wild relative or a rose with less thorns than its wild counterpart.

References and credits

Curtis, S. (1823). Geranium macrorrhizum. Curtis’s Bot. Mag. 50: t. 2420.

Image: Geranium macrorrhizum in Osaka Prefectural Flower Garden, Osaka, Japan. File licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. Available online.

Phillips, R. & Rix, M. (1991). Perennials, Vol. 1. Pan/ Macmillan, London & Firefly, Ontario.

Ploetz, K. & Orr, B. (2004). Wild herb use in Bulgaria. Econ. Bot. 58(2): 231-241.

Radulovic, N.S., Dekic, M.S., Stojanovic-Radic, Z.Z. & Zoranic, S.K. (2010). Geranium macrorrhizum L. (Geraniaceae) essential oil: a potent agent against Bacillus subtilis. Chem. & Biodivers. 7(11): 2783-2800.

Stace, C. (1997). New Flora of the British Isles, 2nd Edition. Cambridge University Press, Cambridge.

Yeo, P. (1985). Hardy Geraniums. Croom Helm, London and Sydney and Timber Press, Portland, Oregon.

Kew Science Editor: Martyn Rix
Kew contributors: Steve Davis (Sustainable Uses Group)
Copyediting: Emma Tredwell

While every effort has been taken to ensure that the information contained in these pages is reliable and complete, the notes on hazards, edibility and suchlike included here are recorded information and do not constitute recommendations. No responsibility will be taken for readers’ own actions.

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