Geranium
Family :
Famille :
Geraniaceae
Synonym(s) :
Synonyme(s) :
Geraniopsis Chrtek (USDA-ARS 2024)
Neurophyllodes (A. Gray) O. Deg. (USDA-ARS 2024)
Robertiella Hanks (USDA-ARS 2024)
Common Name(s) :
Nom(s) commun(s) :
Geranium
(English) (USDA-NRCS 2024)
Cranesbill (English) (USDA-ARS 2024)
Cut-leaved geranium (Geranium dissectum) seeds
Cut-leaved geranium (Geranium dissectum) seeds
Cut-leaved geranium (Geranium dissectum) seed
Cut-leaved geranium (Geranium dissectum) seed
Cut-leaved geranium (Geranium dissectum) seed
Cut-leaved geranium (Geranium dissectum) seed
Geranium molle seeds and mericarps
Geranium molle seed
Geranium molle seed
Geranium molle mericarp
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Overview
Aperçu
Regulation :
Remarques Réglementation:
Regulation Notes:
Distribution :
Répartition :
There are 360 (POWO 2024) to 414 (GBIF 2024) species of Geranium found worldwide on every continent except Antarctica (POWO 2024). They are mostly temperate species of the Northern Hemisphere, although some are found in the temperate Southern Hemisphere, and others are in the tropics where they are mostly restricted to mountainous areas (POWO 2024).
In Canada, 18 species of Geranium are found throughout all of Canada except for Nunavut (Brouillet et al. 2010+). There are 7 native species found throughout the southern provinces and northern Territories (excluding Nunavut and Labrador), 12 introduced species found throughout Canada except Nunavut, and an additional 3 species are also reported but unconfirmed (Brouillet et al. 2010+).
In the United States, 41 Geranium species are found throughout the continental United States, Alaska, and Hawaii; another 3 have been reported but are unconfirmed (USDA-NRCS 2024). There are 20 species of native Geranium found throughout the United States, including five species endemic to Hawaii and another 21 introduced species also found throughout the entire United States (USDA-NRCS 2024).
Habitat and Crop Association :
Habitat et Cultures Associées :
Geranium species can occupy a number of habitats in almost any region other than polar zones, dry deserts and low elevations in tropical areas (Marcussen and Meseguer 2017), but anywhere from sea level to mountainous habitats in temperate zones and in dry climates they occasionally grow as winter annuals (personal observation). The genus generally occupies disturbed habitats such as open woods, clearings, rocky slopes, cultivated fields, forest edges, roadsides, meadows (Aedo 2000; Aedo 2001), as well as waste places and riparian areas (personal observation). Perennial species appear to inhabit more mesic areas such as woodlands, moist meadows and dense weedy areas compared to annual species (Aedo 2002). While in general, they prefer rich, fertile soils, they can be found in poor soils (personal observation). Furthermore, species of Geranium may show a preference for specific conditions, for example, in England Geranium dissectum L. prefers heavy soils, while G. molle L. and G. pusillum L. are only found on light and chalk soils (Brenchley 1913).
Geranium species adapted to disturbed habitats may become arable weeds, but have a relatively low frequency and do not dominate the weed flora (Brenchley 1913; Braithwaite and Gaskell 2021). In both southern Scotland and Czechoslovakia, G. dissectum occupies heavy soils of root crop fields, G. molle and G. pusillum are recorded from drier fields associated with cereal crops (Kolářová et al. 2013; Braithwaite and Gaskell 2021). In England, G. dissectum is also associated with Trifolium pratense L. (red clover) seed samples, and G. molle has been found in T. repens L. (white clover) and T. hybridum L. (Alsike clover) seeds (Brenchley 1913).
In Germany, Geranium species were found in 34% of the Brassica napus L. subsp. napus (canola) fields surveyed, of which G. dissectum had the highest rate, and it was also recorded in B. napus subsp. napus fields in southern England (Froud-Williams and Chancellor 1987; Hanzlik and Gerowit 2012).
Economic Use, cultivation area, and Weed Association :
Utilisation économique, zone de culture et association de mauvaises herbes :
Some Geranium species have been cultivated as garden ornamentals and medicinal plants, but most have been confused with the similar Pelargonium by the general public, horticulturalists and aromatherapists (Liz-Balchin 2002). These two genera were both classified as Geranium species by botanists until the 19th century, and the common name ‘Geranium’ is still used for Pelargonium species in the plant trade (Liz-Balchin 2002).
True Geranium species cultivated as ornamentals are termed ‘hardy geraniums’, as they are native to temperate Europe, Asia and North America; in contrast to Pelargonium species which are native to South Africa and not cold tolerant (Liz-Balchin 2002; Miller 2002). A large number of garden cultivars have been developed from Geranium x oxonianum Yeo, a hybrid of G. endressi J. Gay. and G. versicolor L. (Miller 2002). Ornamentals have also been developed from weedy species such as Geranium robertianum L. and G. pratense L., native to a wide area from northern Europe to China, and G. sylvaticum L., G. sanguineum L., and G. phaeum L., native to southern Europe and Turkey (Miller 2002). Geranium maculatum L. is also popular in cultivation, offering different flower and leaf colours (Mahr n.d.).
Garden ornamentals have also been developed from medicinal Geranium species, for example G. robertianum was used as an astringent, coolant and pain reliever in Europe for hundreds of years (Miller 2002). The ornamental species G. sanguineum and G. macrorrhizum L. remain valuable medicinal species in eastern Europe for essential oils and rhizome extracts, and continue to be produced on a commercial scale in Bulgaria (Stoeva 2002).
Globally, Geranium has been and is still widely used in Indian Ayurveda, Traditional Chinese medicine, and other indigenous medicines. They have significant pharmacological properties, including anticancer, antioxidant, anti-inflammatory, anti-bacterial, and antimicrobial properties (Alshehri 2024), and ongoing research into their medicinal uses is being conducted.
Extracts from medicinal Geranium species contain a high level of tannins with astringent properties, commonly taken internally for gastrointestinal issues, externally for wounds and as an antibacterial agent across many cultures (Williamson 2002). Examples include: Geranium robertianum in Europe, G. thunberghii Sieb et Zucc. in Japan, G. wilfordii Maxim and G. pratense in China, G. core-core L. in Chile and G. niveum S. Watson in Mexico (Williamson 2002).
North American indigenous peoples widely used several Geranium species. They were used as medicines for mouth sores, toothaches, diarrhea, skin sores, venereal diseases and the Walatowa (Jemez) also used it for cordage for sewing moccasins (NAEB 2019).
Duration of Life Cycle :
Durée du cycle vital:
Annual, Perennial, Biennial
Dispersal Unit Type :
Type d’unité de dispersion :
Seed
Distribution of Geranium L. spp. in Canada and the United States (source: USDA-NRCS 2025)
Global distribution of Geranium L. spp. (source: GBIF 2025)
General Information
RENSEIGNEMENTS GÉNÉRAUX
The majority of Geranium species are not considered invasive. However, Geranium lucidum L. is considered an invasive pest throughout the Pacific Northwest of North America, where it shows up as a contaminant in nursery stock and invades disturbed sites like roadsides but also undisturbed native forests and open grassland habitats in the United States in Washington (King County 2024) and Oregon (Oregon State University 2022), and in Canada in British Columbia (Report a Weed BC 2020). Geranium molle L. is another invasive weed around the world (Swearingen and Bargeron 2016), often found in disturbed areas and meadows but does not appear to invade undisturbed habitats (personal observation).
Seeds of Geranium species are dormant when freshly shed through a combination of embryo dormancy and hard-seededness (Baskin and Baskin 1974). The embryo becomes non-dormant after a short ripening period, but the seed coat will remain impermeable to water for longer (Baskin and Baskin 1974; Meisert 2002). Seed coats naturally become permeable over time if left in dry storage dry or by alternating wet and dry storage to mimic the summer season in the field, but the germination may remain low e.g. 50% of G. carolinaum seed germinated after 4.5 months storage (Baskin and Baskin 1974). If the seed coats are mechanically scarified, the seeds will germinate at a high rate after the embryo is matured (Baskin and Baskin 1974).
Geranium viscosissimum Fisch. & C.A.Mey. (sticky geranium), native to the Pacific Northwest of North America, is a curious protocarnivorous plant whose sticky glandular hairs trap insects and use proteinase enzymes to digest and absorb nutrients from the insects (Spomer 1999).
.
Geranium viscosissimum plant with flowers growing on a grassy roadside near Corbett Lake, BC, Canada. Photo by Lyrae Willis.
Identification
Identification
-
Schizocarp
Size
- Schizocarp sizes from literature:
Geranium molle L. (example of small species)
• Schizocarp length: 8-14 mm (Aedo 2000)Geranium pratense L. (example of large species)
• Schizocarp length: 34-36 mm (Aedo 2001)Geranium dissectum L.
• Schizocarp length: 12-17 mm (Aedo 2000)Geranium pusillum L.
• Schizocarp length: 9-11 mm (Aedo 2000)Shape
- Schizocarp has 5 round or oval-shaped lobes, radially arranged around a long stalk
- The style remnants are long, linear and flattened or strap-like, attached to the central stalk
- After dehiscence, the style remnants are curled or coiled, and may remain attached to the central stalk
Surface Texture
- The schizocarp texture of the lobed part may be smooth, irregularly ridged, wrinkled, hairy or hairless depending on the species
- Hairs may be gland-tipped, non-glandular or a mixture of both types (Keshhavarzi and Esfandani-Bozchaloyi 2018)
Colour
- Schizocarp colour of species in subgenus Geranium is generally yellow, yellowish-green, yellowish-brown, light brown or dark brown (Mogadam et al. 2015)
- Schizocarp colour in subgenus Robertium is generally yellow, yellow-brown or light brown (Mogadam et al. 2015)
Other Features
- The characteristic fruit of Geranium consists of a five-lobed ovary with a style that elongates into a prominent, beak-like structure (Yeo 1988). At maturity, each of the five mericarps break apart, and the elongated, ribbon-like style remnant peels away from the central column with explosive force, dispersing the mericarps or seeds away from the parent plant (Marcussen and Meseguer 2017).
- The common English name ‘cranesbill’ comes from its unique schizocarp that resembles a crane’s head and bill where the ovary forms the head, and the extended stigma looks like a beak. This beak has an inner layer that contracts in response to water (hygroscopic) and a stiff outer layer that does not, resulting in coiling and/or bending that aids in seed dispersal (Abraham & Elbaum 2013). This allows their seeds to be explosively expelled several meters from the parent plant.
-
Mericarp
Size
- Mericarp sizes from literature:
Geranium molle L. (example of small species)
• Mericarp length: 1.8-2.1 mm; width: 1.2-1.4 mm (Aedo 2000)
• Mericarp length: 1.4-1.8 mm; width: 0.9-1.3 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium pratense L. (example of large species)
• Mericarp length: 4-6 mm; width: 2.5-3 mm (Aedo 2001)
• Mericarp length: 4.2-4.5 mm; width: 2.1-2.6 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium dissectum L.
• Mericarp length: 2-2.5 mm (Aedo 2000)
• Mericarp length: 2-2.5 mm; width: 1.2-1.8 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium pusillum L.
• Mericarp length: 1.7-1.9 mm; width: 1-1.1 mm (Aedo 2000)
• Mericarp length: 1.7-2 mm; width: 0.9-1 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium robertianum L.
• Mericarp length: 2.5-3.1 mm; width: 1.6-1.8 mm (Aedo 2000)
• Mericarp length: 2.3-2.8 mm; width: 1-1.3 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Shape
- Mericarps are generally oval shaped, oblong or D-shaped, some are round or wedge shaped
Surface Texture
- Mericarp texture may be smooth, irregularly ridged, wrinkled, hairy or hairless depending on the species
- Hairs may be gland-tipped, non-glandular or a mixture of both types (Keshhavarzi and Esfandani-Bozchaloyi 2018)
- G. robertianum mericarps have several ridges clustered at one end with a tuft of long, white hairs that catch on surrounding objects to aid in dispersal (Yeo 1984)
- G. pratense mericarps are generally smooth with glandular hairs, with a ring of stiff bristles at the end opposite the style remnant
- G. lucidum has hooked hairs at one end of the mericarp
- G. pusillum mericarps are covered with dense, appressed hairs
- Species such as G. albanum M. Bieb., G. biuncinatum Ehrh. and G. trilophum Boss. have compressed mericarps with prominent transverse ribs and toothed wings along the edges (Keshavarzi and Esfandani-Bozchaloyi 2018)
Colour
- Mericarp colour of species in subgenus Geranium is generally yellow, yellowish-green, yellowish-brown, light brown or dark brown (Mogadam et al. 2015)
- Mericarp colour in subgenus Robertium is generally yellow, yellow-brown or light brown (Mogadam et al. 2015)
Other Features
- Mericarps are shed with the seed in species of the subgenera Robertium and Erodioideae, and may be found as a crop seed impurity with the seed inside, e.g. Geranium molle, G. robertianum, G. pusillum, G. phaeum.
Three Geranium subgenera have been classified based on the method of seed discharge by Yeo (1984), expanded upon by Marcussen and Meseuger (2017):
- Subgenus Geranium, with the seed ejected from a mericarp that remains attached to the central column. The most common type of seed dispersal, contains approximately 300 Geranium species, widely distributed e.g. G. pratense, G. dissectum.
- Subgenus Robertium, where the mericarp detaches from the column, leaving the awn behind. Contains 30 species, distributed in Europe and western Asia, e.g. G. robertianum, G. molle.
- Subgenus Erodioideae, the mericarp and coiled awn detach and are dispersed together, containing 21 species native to the Mediterranean region, e.g. G. phaeum, G. reflexum L.
Geranium molle mericarp
-
Seed
Size
- Seed sizes from literature:
Geranium molle L. (example of small species)
• Seed length: 1.4-1.8 mm; width: 1-1.2 mm (Aedo 2000)
• Seed length: 1.3-1.5 mm; width: 0.8-1.1 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium pratense L. (example of large species)
• Seed length: 3-3.5 mm; width: 2 mm (Aedo 2001)
• Seed length: 3.2-3.5 mm; width: 2.1-2.3 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium dissectum L.
• Seed length: 1.9-2.1 mm; width: 1.5-1.6 mm (Aedo 2000)
• Seed length: 1.4-1.8 mm; width: 0.8-1.4 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium pusillum L.
• Seed length: 1.7-1.8 mm; width: 1-1.1 mm (Aedo 2000)
• Seed length: 1.5-1.7 mm; width: 0.8-1 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Geranium robertianum L.
• Seed length: 2.1-2.2 mm; width: 1.1-1.2 mm (Aedo 2000)
• Seed length: 1.9-2 mm; width: 0.8-1 mm (Keshavarzi and Esfandani-Bozchaloyi 2018)Shape
- Seeds are generally oval- or oblong-shaped with a truncate hilum end, terete in 3 dimensions
- The radicle is a prominent ridge or rib on one side of the seed
Surface Texture
- Geranium species seeds generally have a ridged reticulate texture, but it may be so small that seeds appear smooth (e.g. G. pusillum reticulation visible at 60x magnification)
- The ridged reticulation of species such as G. columbinum L., G. dissectum, G. maculatum L. and G. pratense are visible under 10x magnification
- A short, linear ridge called the raphe is at one end of the seed that connects the hilum to the chalaza at the end of the seed (Murley 1944)
Colour
- Seed colour is reddish-brown, brown or dark brown
- Reticulation is generally the same colour as the seed, except for yellowish-coloured in G. dissectum and light brown on G. columbinum seeds
Other Features
- The hilum is a small dot on the tip of the radicle on one side of the seed. The hilum is generally close to one end of the seed, but some species have a lateral hilum, e.g. G. maculatum, G. pratense
- Seeds are ejected from the mericarp in subgenus Geranium, and are generally prominent ridged reticulate textured, e.g. Geranium dissectum, G. maculatum, G. pratense
- Seeds of the subgenera that remain in the mericarp when dispersed generally have smooth-appearing seeds e.g. G. molle, G. pusillum, G. robertianum
Cut-leaved geranium (Geranium dissectum) seeds
-
Embryo
Size
- Embryo fills the seed
Shape
- Embryo shape is simple folded
Endosperm
- Nutritive tissue stored in the cotyledons (Martin 1946)
Other Features
- Embryo in an axial position
Identification Tips
CONSEILS POUR L’IDENTIFICATION
The seeds of genera within the Geraniaceae have several distinguishing seed features:
- Seeds are brown or reddish-brown coloured
- The radicle is a prominent ridge or bulge along one side of the seed
- The hilum is located on the tip of the radicle, and a linear raphe extends from the hilum to the end of the seed at the chalaza
- Seed surface is generally ridged reticulate, often only visible under high magnification
- Fruit is a schizocarp, consisting of five single-seeded mericarps and a long, ribbon-like awn that may disperse with the seed or remain on the parent plant
Seeds of Geranium species differ from the similar Erodium and Pelargonium species by:
- Geranium seeds are generally smaller than other genera in the family
- Seeds are oval- or oblong shaped, and terete in 3 dimensions
- Mericarps are dehiscent in subgenus Geranium and remain on the parent plant
Cut-leaved geranium (Geranium dissectum) seed
Additional Botany Information
AUTRES RENSEIGNEMENTS BOTANIQUES
Flowers/Inflorescence
- Flowers are usually in pairs, sometimes solitary, at stem tips or in branch axils (WFO 2024) or in smaller umbels surrounded by small bracts (Alshehri 2024). They have radial symmetry or rarely slightly bilateral symmetry (WFO 2024).
- Petals 5; not joined; equal; sometimes with clawed bases; with rounded or notched tips (WFO 2024); in pink (mostly), purplish, or bluish-pink, and cultivars may have white or blue flowers.
- Sepals 5; overlapping, generally hairy with an obtuse, notched, or pointed tip bearing a tail-like appendage (WFO 2024); the size of sepals usually increases as fruit matures (Alshehri 2024).
- Stamens 10 in 2 whorls with outer whorls opposite the petals (WFO 2024) and often dehiscing before the inner whorls (Alshehri 2024). Only in Geranium pusillum L. are the inner whorls reduced to infertile stamens (staminodes) (WFO 2024).
- Ovary with 5 chambers and 2 ovules per chamber; style is divided into 5 stigmas (WFO 2024) that do not mature until the anthers have dehisced to prevent self-pollination (Alshehri 2024).
- The presence of 10 fertile stamens without wings or staminodes (except Geranium pusillum) differentiates the genus from others in the family that may have 15 fertile stamens united into a ring (nearly all Monsonia L.), five fertile stamens without wings and 5 staminodes (all Erodium L’Hér.), or 10 filaments without wings with 2-7 topped with anthers and the remaining filaments are infertile (all Pelargonium).
Vegetative Features
- Annual, biennial, or perennial herbs; rarely, plants have woody bases that could be classified as shrubs or subshrubs (WFO 2024).
- Stems are usually branched and erect or sprawling.
- Leaves are usually palmately divided (radiating from a single point like fingers on a hand) but may be entire or pinnately lobed (WFO 2024).
- Leaf outline is often rounded or kidney shaped; margins are toothed or entire.
- Basal leaves usually form a rosette, and upper stem leaves are often opposite but may alternate (Alshehri 2024; WFO 2024); they are always stalked (petiolate).
- Small leaf-like appendages (stipules) may or may not be present at the base of leaves.
- Leaf surfaces and margins are often hairy, some hairs have sticky glands on their tips (example Geranium viscosissimum).
Geranium maculatum flowers and floral buds show 5 petals, and buds with hair sepals with long-pointed (caudate) tips. From Old Rope Mill, GA, USA. Photo by Lyrae Willis.
Similar Species
ESPÈCES SEMBLABLES
Similar species are based on a study of seed morphology of various species, and those with similar dispersal units are identified. The study is limited by physical specimen and literature availability at the time of examination, and possibly impacted by the subjectivity of the authors based on their knowledge and experience. Providing similar species information for seed identification is to make users aware of similarities that could possibly result in misidentification.
Erodium LʼHér. species
Mericarps of Erodium species have a persistent, tightly coiled awn, compared to most Geranium mericarps that have a shorter, curved awn. Seeds of Erodium species are generally longer (E. cicutarium (L.) LʼHér. length 2.7 mm, Murley 1944) than Geranium species (G. robertianum length: 1.9-2 mm, (Keshavarzi and Esfandani-Bozchaloyi 2018), are elongated oval-shaped, with one narrow end and a raised chalaza. Geranium seed ends are the same width, and the chalaza is flush with the seed surface.
Pelargonium LʼHér. species
Mericarps of Pelargonium species have a persistent, tightly coiled awn similar to Erodium species. Most Geranium mericarps have a shorter, curved persistent awn. Seeds of Pelargonium species are longer (Pelargonium ×hortorum L. H. Bailey length: 4.2 mm, Murley 1944) than Geranium species (G. robertianum length: 1.9-2 mm, (Keshavarzi and Esfandani-Bozchaloyi 2018), are elongated oval-shaped, with a narrow and protruding radicle ridge and a compressed chalazal end. The radicle of Geranium seeds are not as prominent, and both ends are terete.
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Erodium cicutarium
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MAIN SPECIES
ESPÈCES PRINCIPALES
Geranium
Geranium
Geraniaceae
Cut-leaved geranium (Geranium dissectum) seeds
MAIN SPECIES
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Geranium
Geranium
Geraniaceae
Cut-leaved geranium (Geranium dissectum) seed
MAIN SPECIES
ESPÈCES PRINCIPALES
Geranium
Geranium
Geraniaceae
Cut-leaved geranium (Geranium dissectum) seed
MAIN SPECIES
ESPÈCES PRINCIPALES
Geranium
Geranium
Geraniaceae
Cut-leaved geranium (Geranium dissectum) seed
MAIN SPECIES
ESPÈCES PRINCIPALES
Geranium
Geranium
Geraniaceae
Cut-leaved geranium (Geranium dissectum) seed
MAIN SPECIES
ESPÈCES PRINCIPALES
Geranium
Geranium
Geraniaceae
Geranium molle seeds and mericarps
MAIN SPECIES
ESPÈCES PRINCIPALES
Geranium
Geranium
Geraniaceae
Geranium molle seed
MAIN SPECIES
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Geranium
Geranium
Geraniaceae
Geranium molle seed
MAIN SPECIES
ESPÈCES PRINCIPALES
Geranium
Geranium
Geraniaceae
Geranium molle mericarp
SIMILAR SPECIES
ESPÈCES SEMBLABLES
Erodium cicutarium
Erodium cicutarium
Geraniaceae
Stork’s bill (Erodium cicutarium) mericarps
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Erodium cicutarium
Erodium cicutarium
Geraniaceae
Stork’s bill (Erodium cicutarium) mericarp
SIMILAR SPECIES
ESPÈCES SEMBLABLES
Erodium cicutarium
Erodium cicutarium
Geraniaceae
Stork’s bill (Erodium cicutarium) mericarps
SIMILAR SPECIES
ESPÈCES SEMBLABLES
Erodium cicutarium
Erodium cicutarium
Geraniaceae
Stork’s bill (Erodium cicutarium) mericarp
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Reference(s)
Référence(s)
Abdusalam, A., Tan, D., & Chang, S. M. 2017. Sexual expression and reproductive output in the ephemeral Geranium transversale are correlated with environmental conditions. American journal of botany, 104(12), 1920–1929. https://doi.org/10.3732/ajb.1700258
Abraham, Y. and Elbaum, R. 2013. Hygroscopic movements in Geraniaceae: the structural variations that are responsible for coiling or bending. The New phytologist, 199(2), 584–594. https://doi.org/10.1111/nph.12254
Aedo, C. 2000. The genus Geranium L. (Geraniaceae) in North America. I. Annual species. Anales del Jardín Botánico de Madrid 58: 39-82.
Aedo, C. 2001. The genus Geranium L. (Geraniaceae) in North America. II. Perennial species. Anales del Jardín Botánico de Madrid 59: 3-65.
Alshehri, B. 2024. The geranium genus: A comprehensive study on ethnomedicinal uses, phytochemical compounds, and pharmacological importance. Saudi Journal of Biological Sciences, 31(4). https://doi.org/10.1016/j.sjbs.2024.103940
Braithwaite, M.E. and Gaskell, L.W. 2021. Arable weeds of the Scottish borders. British & Irish Botany 3: 152-160.
Brenchley, W.P. 1913. The weeds of arable land III. Annals of Botany 27: 141-166.
BRIT – NAEB. 2019. Native American Ethnobotany Database. Brit.org. http://naeb.brit.org
Brouillet, L., Coursol, F., Meades, S. J., Favreau, M., Anions, M., Bélisle, P. and Desmet, P. 2010+. VASCAN, the database of vascular plants of Canada. http://data.canadensys.net/vascan Accessed March 09, 2024.
Capital Regional District (CRD). 2020. Shiny Geranium Invasive Species Alert. CRD. www.reportaweedbc.ca
Froud-Williams, R.J. and Chancellor, R.J. 1987. A survey of weeds of oilseed rape in central southern England. Weed Research 27: 187-194.
Global Biodiversity Information Facility (GBIF) Secretariat. 2017. GBIF Home Page https://www.gbif.org Accessed March 9, 2024.
Heap, I. 2024. The International Herbicide-Resistant Weed Database. Online. Available www.weedscience.org Accessed March 9, 2024.
Keshavarzi, M. and Esfandani-Bozchaloyi, S. 2018. Macro- and micro-morphological study of fruits and seeds in the genus Geranium (Geraniaceae). Phytotaxa 371: 185–204.
King County. 2024. Shiny geranium identification and control: Geranium lucidum – King County, Washington. Kingcounty.gov. https://kingcounty.gov/en/dept/dnrp/nature-recreation/environment-ecology-conservation/noxious-weeds/identification-control/shiny%20geranium
Liz-Balchin, M. 2002. General introduction, In: Liz-Balchin, M. (ed.) Geranium and Pelargonium, History of Nomenclature, Usage and Cultivation. CRC Press, London. 344 pp.
Mahr, S. (n.d.). Wild Geranium, Geranium maculatum. Wisconsin Horticulture. https://hort.extension.wisc.edu/articles/wild-geranium-geranium-maculatum
Marcussen, T. and Meseguer, A.S. 2017. Species-level phylogeny, fruit evolution and diversification history of Geranium (Geraniaceae). Molecular Phylogenetics and Evolution 110: 134–149.
Martin, A.C. 1946. The comparative internal morphology of seeds. The American Midland Naturalist 36: 513-660.
Miller, D.M. 2002. The taxonomy of Geranium species and cultivars, their origins and growth in the wild. In: Liz-Balchin, M. (ed.) Geranium and Pelargonium, History of Nomenclature, Usage and Cultivation. CRC Press, London. 344 pp.
Murley, M. 1944. A seed key to fourteen species of Geraniaceae. Proceedings of the Iowa Academy of Science, 51: 241-246.
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