This article is about the botanical genus calledGeranium. For the summer bedding "geranium", seePelargonium. For other uses, seeGeranium (disambiguation).
Geranium is agenus of 422species ofannual,biennial, andperennialplants that are commonly known asgeraniums orcranesbills. They are found throughout thetemperate regions of the world and the mountains of the tropics, with the greatest diversity in the eastern part of theMediterranean region.[1]
The palmately cleftleaves are broadly circular in form. The flowers have five petals and are coloured white, pink, purple, or blue, often with distinctive veining.[1] Geraniums will grow in any soil as long as it is not waterlogged.[2]Propagation is by semiripe cuttings in summer, by seed, or by division in autumn or spring.[3]
Floral diagram of aGeranium garden hybrid called ‘Ann Thomson’, showing 5 free sepals, 5 free petals, 10 free fertile stamens, and a superior ovary consisting of 5 merged carpels, with 5 style branches
The genus name is derived fromAncient Greekγέρανος (géranos) 'crane'. The English name 'cranesbill' derives from the resemblance of thefruit capsule of some of the species to a crane's head and bill. Theovary portion forms the head and the prolongedstigma creates the appearance of a beak.[8][9]
The flowers are typically five-petaled and white to purple. The leaves are palmate divided into narrow, pointed segments.[8]
The fruit capsule consists of five cells joined to a column produced from the centre of the flower. The cells form lobes which eventually separate, each containing one seed.[8] When the fruit is ripe, the beak-like stigma springs open and casts the ovoid, streamlined seeds some distance, dispersing the seeds.[10]
The "bill" and seed dispersal mechanism ofG.pratense
Confusingly, "geranium" is also thecommon name of members of the genusPelargonium, which are also in thefamilyGeraniaceae and are widely grown as horticulturalbedding plants.Linnaeus originally included all the species in one genus,Geranium, but they were later separated into two genera byCharles L’Héritier in 1789.[11] Other former members of the genus are now classified inErodium, including the plants known as filarees in North America.[12]
The term "hardy geranium" is often applied to horticulturalGeraniums to distinguish them from thePelargoniums, which are not winter-hardy intemperate horticulture.[13][14] However, not allGeranium species are winter-hardy (see below).[15]
The shape of the flowers offers one way of distinguishing between the two generaGeranium andPelargonium.Geranium flowers have five very similar petals, and are thus radially symmetrical (actinomorphic), whereasPelargonium (and alsoErodium) flowers have two upper petals which are different from the three lower petals, so the flowers have a single plane of symmetry (zygomorphic).[16][17]
All the above species are perennials and generally winter-hardy plants, grown for their attractive flowers and foliage. They are long-lived and most have a mounding habit, with palmately lobed foliage. Some species have spreading rhizomes. They are normally grown in part shade to full sun, in well-draining but moisture retentive soils, rich inhumus.[18] Other perennial species grown for their flowers and foliage include:Geranium argenteum,G. eriostemon,G. farreri,G. nodosum,G. procurrens,G. pylzowianum,G. renardii,G. traversii,G. tuberosum,G. versicolor,G. wallichianum, andG. wlassovianum. Some of these are not winter-hardy in cold areas and are grown in specialized gardens like rock gardens.[19]Geranium 'Johnson's Blue' is a hybrid betweenG. himalayense (southwestern China), withG. pratense (European meadow cranesbill).[20]
^Hessing, M.B. 1989.Variation in self-fertility and floral characters of Geranium caespitosum(Geraniaceae) along an elevational gradient. Plant Systematics and Evolution 166:225-241.
^abcTaylor, Ronald J. (1994) [1992].Sagebrush Country: A Wildflower Sanctuary (rev. ed.). Missoula, MT: Mountain Press Pub. Co. p. 62.ISBN0-87842-280-3.OCLC25708726.
^"Geranium homeanum".Australian Plants Society. 17 January 2024. Retrieved5 April 2024.
^Phillips, Ellen; Colston Burrell, C. (1993),Rodale's illustrated encyclopedia of perennials, Emmaus, Pa.: Rodale Press, pp. 373–76,ISBN978-0-87596-570-3
^Jelitto, Leo; Schacht, Wilhelm; Epp, Michael E.; Baumgardt (ed. and transl.), John Philip (1990),Hardy herbaceous perennials, vol. 1, Portland, OR: Timber Press, pp. 260–64,ISBN978-0-88192-159-5
Aedo, Carlos; Garmendia, Felix Munoz (February 1996). "Some Notes on the Sectional Nomenclature of Geranium (Geraniaceae)".Taxon.45 (1): 104.doi:10.2307/1222593.JSTOR1222593.
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