Pelargonium

Life-forms

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Rosids
Cladus: Eurosids II
Ordo: Geraniales

Familia: Geraniaceae
Genus: Pelargonium
Subgenera (4):
P. subg. Magnipetala – P. subg. Parvulipetala – P. subg. Paucisignata – P. subg. Pelargonium
Species:
a

P. abrotanifolium – P. acetosum – P. aciculatum – P. acraeum – P. aestivale – P. album – P. alchemilloides – P. alpinum – P. alternans – P. althaeoides – P. anethifolium – P. angustifolium – P. antidysentericum – P. apetalum – P. appendiculatum – P. aridum – P. aristatum – P. artemisiifolium – P. articulatum – P. asarifolium – P. astragalifolium – P. attenuatum – P. auritum – P. australe
b

P. barbatum – P. barklyi – P. betulinum – P. bicolor – P. bifolium – P. bijugum – P. boranense – P. bowkeri – P. brevipetalum – P. brevirostre – P. bubonifolium – P. burtoniae
c

P. caespitosum – P. caffrum – P. caledonicum – P. calviniae – P. campestre – P. candicans – P. capillare – P. capitatum – P. capituliforme – P. carneum – P. carnosum – P. caroli-henrici – P. caucalifolium – P. cavanillesii – P. caylae – P. ceratophyllum – P. chamaedryfolium – P. chelidonium – P. citronellum – P. columbinum – P. confertum – P. cordifolium – P. coronopifolium – P. cortusifolium – P. cotyledonis – P. cradockense – P. crassicaule – P. crassipes – P. crinitum – P. crispum – P. crithmifolium – P. cucullatum – P. curviandrum
d

P. dasyphyllum – P. denticulatum – P. desertorum – P. dichondrifolium – P. dipetalum – P. dispar – P. divisifolium – P. dolomiticum – P. drummondii
e

P. echinatum – P. elegans – P. ellaphieae – P. elongatum – P. endlicherianum – P. englerianum – P. ensatum – P. erlangerianum – P. exhibens – P. exstipulatum
f

P. fasciculaceum – P. fergusoniae – P. fissifolium – P. frutetorum – P. fruticosum – P. fulgidum – P. fumariifolium – P. fumarioides
g

P. gibbosum – P. gilgianum – P. glechomoides – P. glutinosum – P. gracilipes – P. gracillimum – P. grandicalcaratum – P. grandiflorum – P. graveolens – P. grenvilleae – P. greytonense – P. griseum – P. grossularioides
h

P. hantamianum – P. harveyanum – P. hemicyclicum – P. heracleifolium – P. hermanniifolium – P. heterophyllum – P. hirtum – P. hispidum – P. hortorum – P. hypoleucum – P. hystrix
i

P. incarnatum – P. incrassatum – P. inodorum – P. inquinans – P. iocastum – P. ionidiflorum
k

P. karooicum – P. klinghardtense
l

P. laciniatum – P. ladysmithianum – P. laevigatum – P. lanceolatum – P. laxum – P. leipoldtii – P. leptum – P. leucophyllum – P. littorale – P. lobatum – P. longicaule – P. longiflorum – P. longifolium – P. luridum – P. luteolum – P. luteum
m

P. madagascariense – P. magenteum – P. malacoides – P. marginatum – P. moniliforme – P. mossambicense – P. multibracteatum – P. multicaule – P. multiradiatum – P. myrrhifolium
n

P. namaquense – P. nanum – P. nelsonii – P. nephrophyllum – P. nervifolium – P. nivenii
o

P. oblongatum – P. ocellatum – P. ochloleucum – P. odoratissimum – P. oenothera – P. oppositifolium – P. oreophilum – P. otaviense – P. ovale – P. ovalifolium – P. oxalidifolium – P. oxaloides
p

P. panduriforme – P. paniculatum – P. papilionaceum – P. parvipetalum – P. parvirostre – P. parvulum – P. patulum – P. peltatum – P. petroselinifolium – P. pillansii – P. pilosum – P. pinnatum – P. plurisectum – P. polycephalum – P. praemorsum – P. procumbens – P. proliferum – P. pseudofumarioides – P. pseudoglutinosum – P. pulchellum – P. pulcherrimum – P. pulverulentum – P. punctatum
q

P. quarciticola – P. quercetorum – P. quercifolium – P. quinquelobatum
r

P. radens – P. radiatum – P. radicatum – P. radulifolium – P. ramosissimum – P. ranunculophyllum – P. rapaceum – P. redactum – P. reflexipetalum – P. reflexum – P. reniforme – P. reptans – P. ribifolium – P. rodneyanum – P. rubiginosum
s

P. salmoneum – P. scabroide – P. scabrum – P. schizopetalum – P. semitrilobum – P. senecioides – P. sericifolium – P. setosiusculum – P. setulosum – P. sibthorpiifolium – P. sidifolium – P. sidoides – P. spathulatum – P. spinosum – P. squamulosum – P. stipulaceum – P. sublignosum – P. suburbanum – P. sulphureum
t

P. tabulare – P. tenellum – P. tenuicaule – P. ternatum – P. ternifolium – P. tetragonum – P. tomentosum – P. tongaense – P. torulosum – P. tragacanthoides – P. transvaalense – P. triandrum – P. tricolor – P. trifidum – P. trifoliolatum – P. triphyllum – P. triste – P. tysonii
u

P. undulatum
v

P. viciifolium – P. vinaceum – P. violiflorum – P. vitifolium
w

P. whytei – P. woodii
x

P. xerophyton
z

P. zonale
Nothospecies:

P. × ardens – P. × blandfordianum – P. × hybridum – P. × particeps – P. × riversdalense – P. × sanguineum
Name

Pelargonium L'Hér. in Aiton, Hort. Kew. 2: 417 (1789)

Type species: Pelargonium hirsutum (Burm. f.) Sol. ex Aiton
van der Walt, J.J.A & Vorster, P.J. 1981. Taxon 30: 307 argue that the choice of P. hirsutum was made arbitrarily, and that Pelargonium cucullatum (L.) Aiton, designated by van der Walt, J.J.A. (1979) J. S. African Bot. 45: 380 should be the lectotype species.--Fide ING

Synonyms

Heterotypic
Campylia Lindl. ex Sweet, Geraniaceae 1: 75. 1821.
Type species: Campylia holosericea Sweet
Chorisma Lindl. ex Sweet, Geraniaceae 1: 79. 1821.
Type species: Chorisma tetragona Lindl. ex Sweet
Ciconium Sweet, Geraniaceae 1: 9. 1822.
Type species: non design.
Cortusina (DC.) Eckl. & Zeyh., Enum. Pl. Afric. Austral. (Ecklon & Zeyher) 1: 77. 1835.
Type species: non design.
Dibrachya (Sweet) Eckl. & Zeyh., Enum. Pl. Afric. Austral. (Ecklon & Zeyher) 1: 74. 1835.
Type species: non design.
Eumorpha Eckl. & Zeyh., Enum. Pl. Afric. Austral. (Ecklon & Zeyher) 1: 77. 1835.
Geraniospermum Kuntze, Rev. Gen. 1: 93. 1891, nom. illeg.
Type species: Geraniospermum hirsutum (Burm.f.) Kuntze
Hoarea Sweet, Geraniaceae 1: 18. 1820.
Type species: Hoarea corydaliflora Sweet
Isopetalum Sweet, Geraniaceae 1: 126. 1820.
Type species: Isopetalum cotyledonis Sweet
Isopetalum (DC.) Eckl. & Zeyh., Enum. Pl. Afric. Austral. 1: 76. 1834-1835, nom. illeg. & comb. superfl., non Sweet (1822).
Type species: non design.
Jenkinsonia Sweet, Geraniaceae 1: 79. 1821.
Type species: Jenkinsonia quinata (Sims) Sweet, nom. illeg.
Ligularia Eckl. & Zeyh., Enum. Pl. Afric. Austral. 1: 69. 1835, nom. illeg. non Cass., nom. cons. (1816).
Type species: non design.

Note:

There are numerous unresolved species and many hybrids are assumed to be of horticultural origin.
Unresolved hybrid names of Pelargonium

P. × abbreviatum – P. × atropurpureum – P. × balbisianum – P. × barringtonii – P. × blandum – P. × breesianum – P. × calycinum – P. × citriodorum – P. × coarctatum – P. × concinnum – P. × coruscans – P. × cuneatum – P. × daveyanum – P. × dennisianum – P. × erubescens – P. × formosum – P. × hoaraeflorum – P. × mostynae – P. × nervosum – P. × obtusifolium – P. × patens – P. × pavonium – P. × principissae – P. × quinquevulnerum – P. × rhodanthum – P. × rigescens – P. × rubescens – P. × seymouriae – P. × speciosum – P. × spectabile – P. × splendens – P. × tibbitsianum – P. × villosum – P. × wellsianum

Distribution
Native distribution areas:

Continental: Europe
Regional: Northern Europe
Great Britain.
Regional: Middle Europe
Belgium.
Regional: Southwestern Europe
Corse, Spain.
Continental: Africa
Regional: Northern Africa
Morocco.
Regional: Macaronesia
Canary Islands, Cape Verde, Madeira.
Regional: West-Central Tropical Africa
Zaire.
Regional: Northeast Tropical Africa
Eritrea, Ethiopia, Socotra, Somalia, Sudan.
Regional: East Tropical Africa
Kenya, Tanzania, Uganda.
Regional: South Tropical Africa
Angola, Malawi, Mozambique, Zambia, Zimbabwe.
Regional: Southern Africa
Botswana, Cape Provinces, Lesotho, Namibia, KwaZulu-Natal, Free State, Swaziland, Northern Provinces.
Regional: Middle Atlantic Ocean
St.Helena.
Regional: Western Indian Ocean
Madagascar.
Continental: Asia-Temperate
Regional: Middle Asia
Uzbekistan.
Regional: Western Asia
Iraq, Turkey.
Regional: Arabian Peninsula
Saudi Arabia, Yemen.
Regional: Eastern Asia
Korea.
Continental: Asia-Tropical
Regional: Indian Subcontinent
Assam, East Himalaya, India.
Regional: Indo-China
Myanmar, Thailand, Vietnam.
Continental: Australasia
Regional: Australia
Norfolk Islands (extinct), New South Wales, Queensland, South Australia, Tasmania, Victoria, Western Australia.
Regional: New Zealand
Chatham Islands, New Zealand North, New Zealand South.
Continental: Northern America
Regional: Southwestern U.S.A.
California.
Regional: Mexico
Mexico Southwest.
Continental: Southern America
Regional: Central America
Costa Rica.
Regional: Caribbean
Bermuda, Cuba, Dominican Republic, Haiti, Puerto Rico, Trinidad-Tobago.
Regional: Western South America
Ecuador.
Continental: Antarctic
Regional: Subantarctic Islands
Amsterdam-St.Paul Islands, Tristan da Cunha.
Note: Grey script indicates introduced occurrences.

References: Brummitt, R.K. 2001. TDWG – World Geographical Scheme for Recording Plant Distributions, 2nd Edition

References
Primary references

Aiton, W. 1789. Hortus Kewensis; or, a catalogue of the plants cultivated in the Royal Botanic Garden at Kew. Vol. II. Octandria–Monadelphia. 460 pp., tt. 7–10. George Nicol, London. BHL Reference page. : 417.

Additional references

Röschenbleck, J. et al. 2014: Phylogenetics, character evolution and a subgeneric revision of the genus Pelargonium (Geraniaceae). Phytotaxa 159(2): 31–76. DOI: 10.11646/phytotaxa.159.2.1 Reference page.

Links

Govaerts, R. et al. 2021. Pelargonium in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the internet. Accessed: 2021 Sep 6. Reference page.
Tropicos.org 2014. Pelargonium. Missouri Botanical Garden. Published on the internet. Accessed: 2014 Aug 5.
International Plant Names Index. 2014. Pelargonium. Published online. Accessed: Aug 5 2014.

Strlic, M. 2000. The Pelargonium Page. Accessed 2010 April 13 [1].
Vernacular names

беларуская: Пеларгонія
English: Geranium
suomi: Pelargonit
magyar: Muskátli
日本語: テンジクアオイ属
Nederlands: Klimgeranium
polski: Pelargonia
русский: Пеларгония
српски / srpski: Мушкатла
svenska: Pelargonsläktet
Türkçe: Itır
中文: 天竺葵屬

Pelargonium /ˌpɛlɑːrˈɡoʊniəm/[5] is a genus of flowering plants which includes about 280 species of perennials, succulents, and shrubs,[4] commonly known as geraniums, pelargoniums, or storksbills. Geranium is also the botanical name and common name of a separate genus of related plants, also known as cranesbills. Both genera belong to the family Geraniaceae. Carl Linnaeus originally included all the species in one genus, Geranium, and they were later separated into two genera by Charles Louis L'Héritier de Brutelle in 1789.

While Geranium species are mostly temperate herbaceous plants, dying down in winter, Pelargonium species are evergreen perennials indigenous to warm temperate and tropical regions of the world, with many species in southern Africa. They are drought and heat tolerant, but can tolerate only minor frosts. Some species are extremely popular garden plants, grown as houseplants and bedding plants in temperate regions. They have a long flowering period, with flowers mostly in red, orange, or white; but intensive breeding has produced a huge array of cultivars with great variety in size, flower colour, leaf form and aromatic foliage.
Etymology
One of hundreds of garden and houseplant cultivars

The name Pelargonium is derived from the Greek πελαργός, pelargós (stork), because the seed head looks like a stork's beak. Dillenius originally suggested the name 'stork', because Geranium was named after a crane — "a πελαργός, ciconia, sicuti vocamus Gerania, γερανός, grus" (from pelargos, stork, as we call the Gerania, geranos, crane).[6][7]
Description

Pelargonium occurs in a large number of growth forms, including herbaceous annuals, shrubs, subshrubs, stem succulents and geophytes.[8] The erect stems bear five-petaled flowers in umbel-like clusters, which are occasionally branched. Because not all flowers appear simultaneously, but open from the centre outwards, this is a form of inflorescence is referred to as pseudoumbels.

The flower has a single symmetry plane (zygomorphic), which distinguishes it from the Geranium flower, which has radial symmetry (actinomorphic). Thus the lower three (anterior) petals are differentiated from the upper two (posterior) petals. The posterior sepal is fused with the pedicel to form a hypanthium (nectary tube). The nectary tube varies from only a few millimeters, up to several centimeters, and is an important floral characteristic in morphological classification. Stamens vary from 2 to 7, and their number, position relative to staminodes, and curvature are used to identify individual species. There are five stigmata in the style.[9] For the considerable diversity in flower morphology, see figure 1 of Röschenbleck et al. (2014)[8]

Leaves are usually alternate, and palmately lobed or pinnate, often on long stalks, and sometimes with light or dark patterns. The leaves of Pelargonium peltatum (Ivy-leaved Geranium), have a thick cuticle better adapting them for drought tolerance.[10]
ways to reproduce
Rosageranium.grows in water.
Rosageranium flourish in water

Pelargonium are easy to reproduce, just need to cut a part of the plant and put it in water to grow new roots and can be planted again. It can also be propagated by seeds, but the best option is cuttings.
Taxonomy
Dillenius' introduction of the term 'Pelargonium' in Hortus Elthamensis 1732
Pelargonium inquinans, (Geranium Afric. arborescens), Hortus Elthamensis

Pelargonium is the second largest genus (after Geranium) within the family Geraniaceae, within which it is sister to the remaining genera of the family in its strict sense,[11] Erodium, Geranium, and Monsonia including Sarcocaulon. The Geraniaceae have a number of genetic features unique amongst angiosperms, including highly rearranged plastid genomes differing in gene content, order and expansion of the inverted repeat.[8]
Genus history

The name Pelargonium was first proposed by Dillenius in 1732,[12] who described and illustrated seven species of geraniums from South Africa that are now classified as Pelargonium.[13][14] Dillenius, who referred to these seven species with apparent unique characteristics as Geranium Africanum (African Geranium)[15] suggested "Possent ergo ii, quibus novi generis cupido est, ea, quorum flores inaequales vel et irrregulares sunt, Pelargonia vocare" (Those who wish a new genus can therefore call those, whose flowers are unequal or irregular, ‘Pelargonia’).[7] The name was then formally introduced by Johannes Burman in 1738. However Carl Linnaeus who first formally described these plants in 1753 did not recognise Pelargonium and grouped together in the same genus (Geranium) the three similar genera Erodium, Geranium, and Pelargonium.[16] Linnaeus' reputation prevented further differentiation for forty years.[14] The eventual distinction between them was made by Charles L’Héritier based on the number of stamens or anthers, seven in the case of Pelargonium. In 1774, P. cordatum, P. crispum, P. quercifolium and P. radula were introduced, followed by P. capitatum in 1790.[17][13]
Circumscription

Pelargonium is distinguished from the other genera in the family Geraniaceae by the presence of a hypanthium, which consists of an adnate nectar spur with one nectary, as well as a generally zygomorphic floral symmetry.[8]
Subdivision

De Candolle first proposed dividing the genus into 12 sections in 1824, based on the diversity of growth forms.[18] Traditionally the large number of Pelargonium species have been treated as sixteen sections,[9][19] based on the classification of Knuth (1912) who described 15 sections,[20] as modified by van der Walt et al. (1977-1997) who added Chorisma, Reniformia and Subsucculentia.

These are as follows;

section Campylia (Lindley ex Sweet) de Candolle
section Chorisma (Lindley ex Sweet) de Candolle
section Ciconium (Sweet) Harvey
section Cortusina (DC.) Harvey
section Glaucophyllum Harvey
section Hoarea (Sweet) de Candolle
section Isopetalum (Sweet) de Candolle
section Jenkinsonia (Sweet) de Candolle
section Ligularia (Sweet) Harvey
section Myrrhidium de Candolle
section Otidia (Lindley ex Sweet) de Candolle
section Pelargonium (Sweet) Harvey
section Peristera de Candolle
section Polyactium de Candolle
section Reniformia (Knuth) Dreyer
section Subsucculentia J.J.A. van der Walt

Phylogenetic analyses

All subdivision classifications had depended primarily on morphological differences till the era of phylogenetic analyses (Price and Palmer 1993).[11] However phylogenetic analysis shows only three distinct clades, labelled A, B and C.[21] In this analysis not all sections were monophyletic although some were strongly supported including Chorisma, Myrrhidium and Jenkinsonia, while other sections were more paraphyletic. This in turn has led to a proposal, informal at this stage of a reformulation of the infrageneric subdivision of Pelargonium.

In the proposed scheme of Weng et al. there would be two subgenera, based on clades A+B, and C respectively and seven sections based on subclades. Subsequent analysis with an expanded taxa set confirmed this infrageneric subdivision into two groups which also correspond to chromosome length (<1.5 μ, 1.5-3.0μ),[8] but also two subclades within each major clade, suggesting the presence of four subgenera, these correspond to clades A, B, C1 and C2 of the earlier analysis, A being by far the largest clade with 141 taxa. As before the internal structure of the clades supported monophyly of some sections (Myrrhidium, Chorisma, Reniformia, Pelargonium, Ligularia and Hoarea) but paraphyly in others (Jenkinsonia, Ciconium, Peristera). A distinct clade could be identified within the paraphyletic Polyactium, designated section Magnistipulacea. As a result, Polyactium has been split up to provide this new section, which in itself contains two subsections, Magnistipulacea and Schizopetala, following Knuth's original treatment of Polyactium as having four subsections.[8]
Subgenus Magnipetala section Chorisma: P. tetragonum
Subgenus Parvulipetala section Isopetalum: P. cotyledonis
Subgenus Paucisignata section Ciconium: P. acetosum
Subgenus Pelargonium section Campylia: P. tricolor
Subgenus Pelargonium section Otidia: P. crithmifolium

Thus Röschenbleck et al. (2014) provide a complete revision of the subgeneric classification of Pelargonium based on four subgenera corresponding to their major clades (A, B, C1, C2);

subgenus Magnipetala Roeschenbl. & F. Albers Type: Pelargonium praemorsum (Andrews) F Dietrich
subgenus Parvulipetala Roeschenbl. & F. Albers Type: Pelargonium hypoleucum Turczaninow
subgenus Paucisignata Roeschenbl. & F. Albers Type: Pelargonium zonale (L.) L'Hér. in Aiton
subgenus Pelargonium L'Hér. Type: Pelargonium cucullatum (L.) Aiton[8]

Sixteen sections were then assigned to the new subgenera as follows, although many species remained only assigned to subgenera at this stage

subgenus Magnipetala 3 sections
section Chorisma (Lindley ex Sweet) de Candolle - 4 species
section Jenkinsonia (Sweet) de Candolle - 11 species
section Myrrhidium de Candolle - 8 species
subgenus Parvulipetala 3 sections
section Isopetalum (Sweet) de Candolle - 1 species (Pelargonium cotyledonis (L.) L'Hér.)
section Peristera de Candolle - 30 species
section Reniformia (Knuth) Dreyer - 8 species
subgenus Paucisignata 2 sections
section Ciconium (Sweet) Harvey - 16 species
section Subsucculentia J.J.A. van der Walt - 3 species
subgenus Pelargonium 8 sections
section Campylia (Lindley ex Sweet) de Candolle - 9 species
section Cortusina (DC.) Harvey - 7 species
section Hoarea (Sweet) de Candolle - 72 species
section Ligularia (Sweet) Harvey - 10 species
section Magnistipulacea Roeschenbl. & F. Albers Type: Pelargonium schlecteri Knuth - 2 subsections
subsection Magnistipulacea Roeschenbl. & F. Albers Type: Pelargonium schlecteri Knuth - 2 species (P. schlecteri & P. luridum)
subsection Schizopetala (Knuth) Roeschenbl. & F. Albers Type: Pelargonium caffrum (Eckl. & Zeyh.) Steudel - 3 species (P. caffrum, P. bowkeri, P. schizopetalum)
section Otidia (Lindley ex Sweet) de Candolle - 14 species
section Pelargonium L'Hér. - 34 species
section Polyactium de Candolle - 2 subsections
subsection Caulescentia Knuth - 1 species (Pelargonium gibbosum)
subsection Polyactium de Candolle - 7 species

Subgenera

Subgenus Magnipetala: Corresponds to clade C1, with 24 species. Perennial to short lived, spreading subshrubs, rarely herbaceous annuals. Petals five, but may be four, colour mainly white. Mainly winter rainfall region of South Africa, spreading into summer rainfall region. One species in northern Namibia and Botswana. Two species in East Africa and Ethiopia. Chromosomes x=11 and 9.

Subgenus Parvulipetala: Corresponds to clade B, with 39-42 species. Perennials, partly annuals. Petals five and equal, colour white or pink to deep purplish red. Mainly South Africa, but also other southern hemisphere except South America. a few species in East Africa and Ethiopia. Chromosomes x=7-19.

Subgenus Paucisignata: Corresponds to clade C2, with 25-27 species. Erect sometimes trailing shrubs or subshrubs, rarely geophytes or semi-geophytes. Petals five and equal, colour pink to red sometimes white. Summer rainfall region of South Africa, spreading into winter rainfall region and northern Namibia, with a few species in tropical Africa, Ethiopia, Somalia, Madagascar, the Arabian Peninsula and Asia Minor. Chromosomes x=mainly 9 or 10, but from 4-18.

Subgenus Pelargonium: Corresponds to clade A, with 167 species. Frequently xerophytic deciduous perennials with many geophytes and succulent subshrubs, less frequently woody evergreen shrubs or annual herbs. Petals five, colour shades of pink to purple or yellow. Winter rainfall region of South Africa and adjacent Namibia, spreading to summer rainfall area, and two species in tropical Africa. Chromosomes x=11, may be 8-10.[8]
Species
Main article: List of Pelargonium species

Pelargonium has around 280 species.[4][21] Röschenbleck et al lists 281 taxa.[8] There is considerable confusion as to which Pelargonium are true species, and which are cultivars or hybrids. The nomenclature has changed considerably since the first plants were introduced to Europe in the 17th century.[22]
Distribution

Pelargonium is a large genus within the family Geraniaceae, which has a worldwide distribution in temperate to subtropical zones with some 800 mostly herbaceous species.[8] Pelargonium itself is native to southern Africa (including Namibia) and Australia. Southern Africa contains 90% of the genus, with only about 30 species found elsewhere, predominantly the East African rift valley (about 20 species) and southern Australia, including Tasmania.[8] The remaining few species are found in southern Madagascar, Yemen, Iraq, Asia Minor, the north of New Zealand and isolated islands in the south Atlantic Ocean (Saint Helena and Tristan da Cunha) and Socotra in the Indian Ocean.[8] The centre of diversity is in southwestern South Africa where rainfall is confined to the winter, unlike the rest of the country where rainfall is predominantly in the summer months.[8] Most of the Pelargonium plants cultivated in Europe and North America have their origins in South Africa.[22]
Ecology

Pelargonium species are eaten by the caterpillars of some Lepidoptera species, including the noctuid moth angle shades, Phlogophora meticulosa. The diurnal butterflies Cacyreus marshalli and C. tespis (Lycaenidae), native to southern Africa, also feed on Geranium and Pelargonium.[23] C. marshallii has been introduced to Europe and can develop into a pest on cultivated Pelargoniums. It has naturalised along the Mediterranean, but does not survive the winter in Westen Europe.[24]

The Japanese beetle, an important agricultural insect pest, becomes rapidly paralyzed after consuming flower petals of the garden hybrids known as "zonal geraniums" (P. × hortorum). The phenomenon was first described in 1920, and subsequently confirmed.[25][26][27][28] Research conducted by Dr. Christopher Ranger with the USDA Agricultural Research Service and other collaborating scientists have demonstrated the excitatory amino acid called quisqualic acid present within the flower petals is responsible for causing paralysis of the Japanese beetle.[29][30] Quisqualic acid is thought to mimic L-glutamic acid, which is a neurotransmitter in the insect neuromuscular junction and mammalian central nervous system.[31]

A study by the Laboratory of Apiculture & Social Insects group at the University of Sussex on the attractiveness of common garden plants to pollinators found that a cultivar of Pelargonium × hortorum was unattractive to pollinators in comparison to other selected garden plants such as Lavandula (lavender) and Origanum.[32]
Pests and diseases
Main articles: List of geranium diseases, Pelargonium flower break virus, and Pelargonium line pattern virus

The geranium bronze butterfly is a pest of Pelargonium species. The larvae of the geranium bronze bore into the stem of the host plant, causing the stem to typically turn black and die soon after. Geranium bronze are currently listed as an A2 quarantine pest by the European and Mediterranean Plant Protection Organization and can cause significant damage to Pelargonium species.[33]
Cultivation
Pelargonium triste, the first species of its genus to be cultivated, here shown in its native habitat in Cape Town

Various types of Pelargonium are regular participants in flower shows and competitive events, with numerous societies devoted exclusively to their cultivation. They are easy to propagate vegetatively from cuttings.[34][35][36] Zonal geraniums grow in U.S. Department of Agriculture hardiness zones 9 through 12. Zonal geraniums are basically tropical perennials. Although they are often grown as annuals, they may overwinter in zones as cool as zone 7.[37]
Cultivation history

The first species of Pelargonium known to be cultivated was P. triste, a native of South Africa. It was probably brought to the Botanical Garden in Leiden before 1600 on ships which had stopped at the Cape of Good Hope. In 1631, the English gardener John Tradescant the elder bought seeds from Rene Morin in Paris and introduced the plant to England. By 1724, P. inquinans, P. odoratissimum, P. peltatum, P. vitifolium, and P. zonale had been introduced to Europe.[17]
Cultivars
Zonal pelargonium

There was little attempt at any rational grouping of Pelargonium cultivars, the growing of which was revived in the mid-twentieth century, and the origins of many if not most were lost in obscurity. In 1916 the American botanist Liberty Hyde Bailey (1858–1954) introduced two new terms for zonal and regal pelargoniums. Those pelargoniums which were largely derived from P. zonale he referred to as P. × hortorum (i.e. from the garden), while those from P. cucullatum he named P. × domesticum (i.e. from the home).[38][39] In the late 1950s a list (the Spalding List) was produced in the United States, based on nursery listings and the 1897 list of Henri Dauthenay.[40] It described seven groups, listing each cultivar with the list of its originator, and in most cases a date. These were Species, Zonals, Variegated-Leaved, Domesticum (Regals), Ivy-Leaved, Scented-Leaved and Old. In the 1970s the British Pelargonium and Geranium Society produced a checklist and the Australian Geranium Society started to produce a register but it was not completed till its author, Jean Llewellyn's death in 1999. None of these were published. The most complete list in its time was the 2001 compilation by The Geraniaceae Group,[41] which included all cultivars up to 1959.[42]

Registration of cultivars is the responsibility of the Pelargonium & Geranium Society (PAGS: formed in 2009 from the British Pelargonium and Geranium Society and the British and European Geranium Society)[43] which administers the International Register of Pelargonium Cultivars.[44] PAGS is the International Cultivar Registration Authority (ICRA) of the International Society for Horticultural Science for pelargoniums.[45]
Contrasting leaves: Ivy-leaved Group (Left) Zonal Group (Right)

Cultivated pelargoniums are commonly divided into six groups[46] in addition to species pelargoniums and primary hybrids. The following list is ordered by position in the PAGS classification.[47] Abbreviations indicate Royal Horticultural Society usage.[48]

A. Zonal (Z)
B. Ivy-leaved (I)
C. Regal (R)
D. Angel (A)
E. Unique (U)
F. Scented-leaved (Sc)
G. Species
H. Primary hybrids

Of these, A, U and Sc groups are sometimes lumped together as Species Derived (Sppd). This term implies that they are closely related to a species from which they were derived, and do not fit into the R, I or Z groups.[49]

In addition to the primary groups, additional descriptors are used. The Royal Horticultural Society has created description codes. These include;[48]

Cactus (Ca)
Coloured foliage (C)
Decorative (Dec)
Double (d)
Dwarf (Dw)
Dwarf Ivy-leaved (Dwl)
Frutetorum (Fr)
Miniature (Min)
Miniature Ivy-leaved (MinI)
Stellar (St)
Tulip (T)
Variegated (v)

These may then be combined to form the code, e.g. Pelargonium 'Chelsea Gem' (Z/d/v), indicating Zonal Double with variegated foliage.[50] Crosses between groups are indicated with an ×, e.g. Pelargonium 'Hindoo' (R × U), indicating a Regal × Unique cross.[51]
A. Zonal pelargoniums (Pelargonium × hortorum Bailey)
Pelargonium × hortorum (Zonal)

These are known as zonal geraniums because many have zones or patterns in the center of the leaves,[36] this is the contribution of the Pelargonium zonale parent. Common names include storksbill, fish or horseshoe geraniums.[49] They are also referred to as Pelargonium × hortorum Bailey. Zonal pelargoniums are tetraploid, mostly derived from P. inquinans and P. zonale,[52] together with P. scandens and P. frutetorum.[36][46]

Zonal pelargoniums are mostly bush-type plants with succulent stems grown for the beauty of their flowers, traditionally red, salmon, violet, white or pink.[36] The scarlet colouring is attributed to the contribution of P. inquinans.[17] Flowers may be double or single. They are the pelargoniums most often confused with genus Geranium, particularly in summer bedding arrangements. This incorrect nomenclature is widely used in horticulture, particularly in North America.[17]

Zonals include a variety of plant types along with genetic hybrids such as hybrid ivy-leaved varieties that display little or no ivy leaf characteristics (the Deacons varieties), or the Stellar varieties. Hybrid zonals are crosses between zonals and either a species or species-derived pelargonium.[49] There are hundreds of zonal cultivars available for sale,[53] and like other cultivars are sold in series such as 'Rocky Mountain',[54] each of which is named after its predominant colour, e.g. 'Rocky Mountain Orange', 'White', 'Dark Red', etc.[55]
'Rocky Mountain Orange' (Zonal)

(i) Basic plants – Mature plants with foliage normally exceeding 180 mm (7 in) in height above the rim of the pot. For exhibition these should be grown in a pot exceeding 120 mm (4+3⁄4 in) in diameter but not normally exceeding 165 mm (6+1⁄2 in).
(ii) Dwarf plants – Smaller than basic. Mature plants with foliage more than 125 mm (5 in) above the rim of the pot, but not normally more than 180 mm (7 in). For exhibition should be grown in a pot exceeding 90 mm (3+1⁄2 in) but not exceeding 120 mm (4+3⁄4 in). They should not exceed 200 mm in height, grown in an 11 cm pot.[49]
(iii) Miniature plants – Slowly growing pelargoniums. Mature plants with foliage normally less than 125 mm (5 in) above the rim of the pot. For exhibition should be grown in a pot not exceeding 90 mm (3+1⁄2 in). They should not exceed 125 mm in height, grown in a 9 cm pot.[49]
(iv) Micro-miniature plants – Smaller and more slowly growing than miniature pelargoniums. Mature plants with foliage normally less than 100 mm (4 in) above the rim of the pot. They should not exceed 75 mm in height, grown in a 6 cm pot.[49] Usually no separate classes for these in exhibition and will therefore normally be shown as Miniature Zonals.
(v) Deacon varieties –Genetic hybrid similar to a large Dwarf. For exhibition (when shown in a separate class), usually grown in a pot not exceeding 125 mm (5 in), otherwise as for Dwarf Zonals.
(vi) Stellar varieties – A relatively modern genetic hybrid originating from the work done by the Australian hybridiser Ted Both in the late 1950s and 1960s from crosses between Australian species and Zonal types. Easily identifiable by their distinctive half-star-shaped leaves and slim-petalled blooms which create an impression of being star shaped (or five fingered). Single varieties tend to have larger elongated triangular petals whereas doubles tend to have thin feathered petals that are tightly packed together. For exhibition purposes there is a separate class for 'Stellar' varieties, but being Zonals could be shown in an open class for Basic, Dwarf or Miniature Zonals (unless otherwise stated). Also known as "The Five-fingered Geraniums", "Staphysagroides", "Both’s Staphs", "Both’s Hybrid Staphs", "Fingered Flowers" and "Bodey’s Formosum Hybrids".[49]

Fancy-leaf zonal pelargoniums – besides having green leaves with or without zoning, this group also have variable coloured foliage[49] that is sometimes used in classifying for exhibition purposes, e.g. ‘Bicolour’, ‘Tricolour’, ‘Bronze’ or ‘Gold’. Other foliage types are: ‘Black’ or ‘Butterfly’. There are an increasing number of these plants with showy blooms;

(a) Bicolour – includes those with white or cream veined leaves or those with two distinct colours with clearly defined edges, other than the basic zone.
(b) Tricolour – (May be Silver Tricolour (usually called a Silver Leaf) or a Gold Tricolour).
(i) Gold Tricolour – Leaves of many colours including red and gold, but usually with clearly defined edges of golden yellow and having a leaf zone, usually red or bronze, that overlays two or more of the other distinct leaf colours, so that the zone itself appears as two or more distinct colours.
(ii) Silver Tricolour or Silver Leaf – These tend to resemble a normal bi-colour leaf plant with two distinct colours usually of green and pale cream or white; the third colour is usually made up of bronze zoning. When this zoning overlays the green part of the leaf it is deemed to represent a silver colour.
(c) Bronze Leaved – Leaves of Green or Golden/Green with a heavy bronze or chestnut coloured centre zone which is known as a medallion. For exhibition purposes, when exhibited in specific ‘Bronze’ Leaf class – Must have over 50% of leaf surface bronze coloured. The dwarf plant ‘Overchurch’ which has a heavy bronze medallion.
(d) Gold Leaved – Leaves coloured golden/yellow or green/yellow but not showing a tendency to green. For exhibition purposes, when exhibited in specific ‘Gold’ Leaf class – Must have over 50% of leaf surface gold coloured.
(e) Black Leaved – Leaves coloured black, purple-black or with distinct large dark zones or centre markings on green.
(f) Butterfly Leaved – Leaves with a butterfly marking of distinct tone or hue in centre of leaf. This can be encompassed in many of the coloured leaf varieties.

Zonal pelargoniums have many flower types, as follows:[49]

(a) Single flowered (S) – each flower pip normally having no more than five petals. This is the standard flower set for all Pelargoniums.
(b) Semi-double flowered (SD) – each flower pip normally having between six and nine petals.
(c) Double flowered (D)– each flower pip composed of more than nine petals (i.e. double the standard flower set) but not ‘hearted’ like the bud of a rose, e.g. the dwarf ‘Dovepoint’ which has full double blooms.
(d) Rosebud (or noisette) flowered – each bloom fully double and ‘hearted’. The middle petals are so numerous that they remain unopened like the bud of a rose.[49]
(e) Tulip flowered – having semi-double blooms that never fully open. The large cup shaped petals open just sufficiently to resemble a miniature tulip.
(f) Bird's-egg group – having blooms with petals that have spots in a darker shade than the base colour, like many birds eggs.[49]
(g) Speckled flowered group – having petals that are marked with splashes and flecks of another colour, e.g. ‘Vectis Embers’.
(h) Quilled (or cactus-flowered group, or poinsettia in USA) – having petals twisted and furled like a quill.[49]

“Zonquil” pelargoniums result from a cross between Zonal pelargonium cultivars and P. quinquelobatum.[49]
B. Ivy-leaved pelargoniums (derived from Pelargonium peltatum)
Pelargonium peltatum (Ivy-leaved)

Also known as "ivy geraniums".[49]Usually of lax growth (trailing), mainly due to the long thin stems, with thick, waxy ivy-shaped stiff fleshy evergreen leaves developed by the species P. peltatum to retain moisture during periods of drought. Much used for hanging pots, tubs and basket cultivation. In the UK the bulbous double-headed types are preferred whilst on the European continent the balcon single types for large-scale hanging floral displays are favoured. Ivy-leaved pelargoniums embrace all such growth size types including small-leaved varieties and genetic hybrid crosses, which display little or no zonal characteristics. May have bicolour leaves and may have flowers that are single, double or rosette. Ivy pelargoniums are often sold as series such as 'Great Balls of Fire', in a variety of colours such as 'Great Balls of Fire Burgundy'.

Additional descriptive terms include;[49]

Hybrid Ivy — the result of ivy × zonal crosses, but still more closely resemble ivy-leaved pelargoniums.
Fancy leaf — leaves with marked color variation, together with or other than green.
Miniature — miniature leaves and flowers, stems with short nodes, and compact growth. e.g. 'Sugar Baby'[56] listed as Dwarf Ivy (DwI) by RHS.[48]

C. Regal pelargoniums (Pelargonium × domesticum Bailey)
'Karl Offenstein' (Regal)

These are large bush-type floriferous evergreen pelargoniums. In addition to "Regals" they are also known as “Show Pelargoniums”. In the United States they are often known as the "Martha Washington" or ‘"Lady Washington" pelargoniums. They are grown primarily for the beauty and richness of their flower heads, which are large. Most of those cultivars grown currently are the result of hybridization over the last 50 years. They are very short-jointed and compact, which results in their requiring very little work in order to create a floriforous and well-rounded plant.[49][47] Flowers are single, rarely double, in mauve, pink, purple or white. They have rounded, sometimes lobed or partially toothed (serrated) leaves, unlike the Zonal groups, without any type of zoning.

Additional descriptive terms include;[49]

Fancy leaf – Leaves with marked variations in colour
Decorative pelargoniums (Decoratives) – Descendants of older, less compact, smaller-flowered varieties that are more suited to outdoor conditions. These have smaller flowers than Regal, but are otherwise similar. e.g. ‘Royal Ascot’
Miniature – Flowers and leaves similar to Regal, but miniature in form, with compact growth. Other terms include “Pansy Geraniums” or “Pansy Pelargoniums”. e.g. ‘Lara Susan’
Oriental pelargoniums – The result of crosses between Regals and members of the Angel group (see below). Some have bicolour foliage.

D. Angel pelargoniums (derived from Pelargonium crispum)
'Angeleyes Randy' (Angel)

Angel pelargoniums are similar to Regal pelargoniums but more closely resemble P. crispum in leaf shape and growth habit. The majority of Angel cultivars originate from a cross between P. crispum and a Regal variety in the early part of the 20th century. Angels have grown in popularity in the last 30 years or so due mainly to an explosion of new varieties being released by specialist nurseries resulting from the work done by dedicated amateur hybridisers. These hybrisers have managed to obtain many new flower colour breaks and tighter growth habits resulting in plants suitable for all sorts of situations. Angels basically have the appearance of a small Regal with small serrated leaves and much smaller flowers and are more compact and bushy. The group extends to include similar small-leaved and -flowered types but usually with P. crispum in their parentage. They are mostly upright bush-type plants but there are some lax varieties that can be used for basket or hanging pot cultivation. Often called "pansy-faced" in the US. Some varieties have bicolour foliage. Other terms include ‘Langley-Smith Hybrids’.[49]
E. Unique pelargoniums (derived from Pelargonium fulgidum)
'White Unique' (Unique)

Unique in sense of not fitting into any of the above categories. The parentage of Unique pelargoniums is confused and obscure. One theory being a derivation from P. fulgidum, but a derivation from an older cultivar 'Old Unique’, also known as or ‘Rollinson’s Crimson’, in the mid-19th century is also claimed.[49] Unique pelargoniums resemble upright Scented Leaf pelargoniums in being shrubby and woody evergreens. They have distinctly scented leaves, and small flowers with blotched and feathered petals. They may have bicolour foliage. Some types, popularly known in the hobby as hybrid Uniques, have been crossed with Regal pelargoniums and, as a result of this cross, are much more floriferous.

Cultivar

Fiery-flowered Stork's-bill, Scarlet Unique Scented Geranium (P. × ignescens)[57] - a P. fulgidum hybrid[58]

F. Scented-leaved pelargoniums
Pelargonium graveolens (Scented leaf)

Shrubby evergreen perennials grown chiefly for their fragrance, may be species or cultivars but all must have a clear and distinct scented foliage. Scent is emitted when the leaves are touched or bruised with some scents aromatic, others pungent and in a few cases, quite unpleasant. Several of the scented leaved pelargoniums are grown for the oil geraniol, which is extracted from the leaves and is an essential oil much used commercially in perfumery. The scent of some species growing in their natural habitat, acts as a deterrent to grazing animals who appear to dislike the emitted scent. Conversely, it also attracts other insect life to visit the bloom and pollinate the plant. The scented leaves can be used for potpourri and they also have a use as flavourings in cooking. Occasionally scented types can be found in some of the other groups mentioned; for example, the Angels, having P. crispum in their genetic makeup, can often have a strong citrus scent. Leaves are lobed, toothed, incised or variegated. Growth habit is very variable, but the flowers are less prominent than other groups, and most closely resemble the species they originated from.[49]

These include:
Pelargonium quercifolium 'Fair Ellen' (Scented leaf)
Pelargonium ionidiflorum (Scented leaf)

Almond - Pelargonium quercifolium
Apple - Pelargonium odoratissimum
Apple - Pelargonium cordifolium
Apple/Mint - Pelargonium album
Apricot/Lemon - Pelargonium scabrum
Balsam - Pelargonium panduriforme
Camphor - Pelargonium betulinum
Celery - Pelargonium ionidiflorum
Cinnamon - Pelargonium 'Ardwyck Cinnamon'
Coconut - Pelargonium grossalarioides (Pelargonium parriflorum)
Eau de Cologne - Pelargonium 'Brilliantine'
Eucalyptus - Pelargonium 'Secret Love'
Grapefruit - Pelargonium 'Poquita'
Ginger - Pelargonium 'Torrento' or 'Cola Bottles' which is a variety of Pelargonium x nervosum
Hazelnut - Pelargonium 'Odorata Hazelnut
Lavender - Pelargonium 'Lavender Lindy'
Lemon - Pelargonium crispum
Lemon - Pelargonium citronellum (Synonym - Pelargonium 'Mabel Grey')
Lemon Balm - Pelargonium x melissinum
Lime - Pelargonium x nervosum
Myrrh - Pelargonium myrrhifolium
Nutmeg - Pelargonium x fragrans
Old Spice - Variety of Pelargonium x fragrans
Orange - Pelargonium x citriodorum (Synonym - Pelargonium 'Prince of Orange')
Peach - Pelargonium 'Peaches and Cream'
Peppermint - Pelargonium tomentosum
Pine - Pelargonium denticulatum
Pineapple - Pelargonium 'Brilliant'
Raspberry - Pelargonium 'Red Raspberry'
Rose - Pelargonium graveolens (Synonym - Pelargonium roseum)
Rose - Pelargonium capitatum
Rose - Pelargonium radens
Southernwood - Pelargonium abrotanifolium
Spicy - Pelargonium exstipulatum
Strawberry - Pelargonium x scarboroviae

Cultivars

'Attar of Roses' - a cultivar of P. capitatum
'Crowfoot Rose' - a cultivar of P. radens
'Dr. Livingston' - a cultivar of P. radens
'Grey Lady Plymouth' - a cultivar of P. graveolens
'Prince Rupert' - a cultivar of P. crispum

G. Species pelargoniums

The species are the forefathers of all the cultivar groups listed above. In general, the definition of a species is that it breeds true, and is to be found doing this in the "wild". Species pelargoniums have a large diversity of characteristics in habit, shape, size and colour, which probably accounts for them having retained their popularity for more than 300 years.
H. Primary hybrids

A primary hybrid is recognised as being the resultant plant from a first-time cross between two different known species. Examples are P. × ardens – from P. lobatum × P. fulgidum (1810). P. × glauciifolium – from P. gibbosum × P. lobatum (1822). Usually, but not always, primary hybrids are sterile.
List of AGM pelargoniums
'Attar of Roses'
'Lady Plymouth'
'Mabel Gray'

The following is a selection of pelargoniums which have gained the Royal Horticultural Society's Award of Garden Merit:

'Attar of Roses' (rose scented leaves, pink flowers)[59]
'Citriodorum' (lemon scented leaves, rose pink flowers)[60]
'Dolly Varden' (variegated leaves, scarlet flowers)[61]
'Frank Headley' (cream vareigated leaves, salmon pink flowers)[62]
'Fringed Aztec' (white & purple fringed flowers)[63]
'Gemstone' (scented leaves, pink flowers)[64]
'Grace Thomas' (lemon scented leaves, pale pink flowers)[65]
'Joy' (pink & white frilled flowers)[66]
'Lady Plymouth' (P. graveolens variegata - small mauve flowers)[67]
'Lara Candy Dancer' (scented leaves, pale mauve flowers)[68]
'Lara Starshine' (aromatic leaves, lilac flowers)[69]
'L'Élégante' (ivy-leaved, trailing, white and purple flowers)[70]
'Mabel Grey' (lemon-scented leaves, mauve flowers)[71]
'Mrs Quilter' (bronze leaves, salmon pink flowers)[72]
'Radula' (lemon & rose scented leaves, pink & purple flowers)[73]
'Royal Oak' (balsam scented leaves, mauve flowers)[74]
'Spanish Angel' (lilac & magenta flowers)[75]
'Sweet Mimosa' (balsam-scented leaves, pale pink flowers)[76]
'Tip Top Duet' (pink & wine-red flowers)[77]
'Voodoo' (crimson & black flowers)[78]
P. tomentosum (peppermint-scented leaves, small white flowers)[79]

Usage
Ornamental plants

Pelargoniums rank as one of the highest number of potted flowering plants sold and also in terms of wholesale value.[36]
Scented leaf pelargoniums

Other than being grown for their beauty, species such as P. graveolens are important in the perfume industry and are cultivated and distilled for their scents. Although scented pelargoniums exist which have smells of citrus, mint, pine, spices or various fruits, the varieties with rose scents are most commercially important. Pelargonium distillates and absolutes, commonly known as "scented geranium oil" are sometimes used to supplement or adulterate expensive rose oils. The oils of the scented pelargoniums contain citronellol, geraniol, eugenol, alpha pinene and many other compounds. The edible leaves and flowers are also used as a flavouring in desserts, cakes, jellies and teas. Scented-leafed pelargoniums can be used to flavor jellies, cakes, butters, ice cream, iced tea and other dishes, The rose-, lemon- and peppermint-scents are most commonly used. Also used are those with hints of peach, cinnamon and orange. Commonly used lemon-scented culinary species include P. crispum and P. citronellum. Rose-scenteds include P. graveolens and members of the P. graveolens cultivar group. Other species and cultivars with culinary use include the lime-scented P. ‘Lime’, the lemon balm-scented P. ‘Lemon Balm’, the strawberry-lemon-scented P. ‘Lady Scarborough’ and the peppermint-scented P. tomentosum.[80]
Herbal medicine

In herbal medicine, Pelargonium has been used for intestinal problems, wounds and respiratory ailments, but Pelargonium species have also been used for fevers, kidney complaints and other conditions. Geranium (Pelargonium) oil is considered a relaxant in aromatherapy, and in recent years, respiratory/cold remedies made from P. sidoides and P. reniforme have been sold in Europe and the United States.[80] P. sidoides along with Echinacea is used for bronchitis.[81] P. odoratissimum is used for its astringent, tonic and antiseptic effects. It is used internally for debility, gastroenteritis, and hemorrhage and externally for skin complaints, injuries, and neuralgia and throat infections. The essential oil is used in aromatherapy.[82]
Chemistry

Pelargonin (pelargonidin 3,5-O-diglucoside) is a petal pigment of the scarlet pelargonium.[83]
Culture

The chemist, John Dalton, realized that he was color blind in 1794 when he heard others describe the color of the flowers of the pink Pelargonium zonale[84] as pink or red, when to him it looked either pink or blue, having no relationship to red at all.[85]
Notes

The generic description of Pelargonium in Hortus Kewensis was copied from L’Heritier’s unpublished manuscript titled Compendium Generalogium[2]

It has been stated that the choice of P. hirsutum was made arbitrarily,[3] and that Pelargonium cucullatum (L.) Aiton, designated by van der Walt[2] should be the lectotype species. Furthermore, P. hirsutum is not currently recognised as an accepted name.

References

William Aiton (1789). Hortus Kewensis. ii. London: Nicol. p. 417.
van der Walt 1979.
van der Walt & Vorster 1981.
"Pelargonium L'Hér. ex Aiton". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2 August 2020.
Sunset Western Garden Book, 1995:606–607
Dillenius 1732, De Geraniorum Differentiis.
Boddy 2013, Introduction p. 11.
Roschenbleck et al 2014.
The Pelargonium Page
Appell, Scott D. (2001). The Potted Garden: New plants and New approaches for container gardens. p. [page needed]. ISBN 978-1889538228.
Robert A. Price and Jeffrey D. Palmer. Phylogenetic Relationships of the Geraniaceae and Geraniales from rbcL Sequence Comparisons. Annals of the Missouri Botanical Garden Vol. 80, No. 3 (1993), pp. 661-671
Dillenius 1732, De Geraniorum Differentiis p. 149.
Handlos, Wayne (2013). "18th Century: Important People, Dates and Publications in the History of Pelargonium". Geraniums Online. Central Coast Geranium Society. Retrieved 3 August 2017.
Lis-Balchin 2002, Diana Miller. The taxonomy of Pelargonium species and cultivars: Classification history p. 52.
Dillenius 1732, Geranium Africanum p. 151.
Linnaeus 1753, Geranium p. 676.
Taylor 2014, Pelargonium.
A. P. de Candolle; et al. (1824–1873). "Geraniaceae: Pelargonium". Prodromus systematis naturalis regni vegetabilis sive enumeratio contracta ordinum, generum specierumque plantarum huc usque cognitarum, juxta methodi naturalis normas digesta. I. Sumptibus Sociorum Treuttel et Würtz. p. 649. (also available online at Gallica)
Handlos, Wayne (2010). "The Sections of Pelargonium". Geraniums Online. Central Coast Geranium Society. Retrieved 3 August 2017.
Knuth, R (1912). "5: Pelargonium L'Hér.". In Adolf Engler (ed.). Das Pflanzenreich: regni vegetablilis conspectus (in German). 129: Geraniaceae. Leipzig: Engelmann. p. 316. Retrieved 16 August 2014.
Weng, ML; Ruhlman, TA; Gibby, M; Jansen, RK (Sep 2012). "Phylogeny, rate variation, and genome size evolution of Pelargonium (Geraniaceae)". Mol Phylogenet Evol. 64 (3): 654–70. doi:10.1016/j.ympev.2012.05.026. PMID 22677167.
Sayre, James K. (2003). "Scented Geraniums or Pelargoniums". Bottlebrushpress.com. Archived from the original on 2011-07-08.
"Butterflies of Kwazulu-Natal" (PDF). Durban Natural Science Museum Novitates.
Peter Eeles. "Geranium bronze". UK Butterflies. Retrieved 2017-09-26.
Davis, J.J. 1920. The green Japanese beetle. New Jersey Department of Agriculture Circular. 30: 33.
Ballou, C. H. (1929). "Effects of geranium on the Japanese beetle". Journal of Economic Entomology. 22 (2): 289–293. doi:10.1093/jee/22.2.289.
Potter, D. A.; Held, D. W. (1999). "Absence of food-aversion learning by a polyphagous scarab, Popillia japonica, following intoxication by geranium, Pelargonium x hortorum". Entomologia Experimentalis et Applicata. 91: 83–88. doi:10.1046/j.1570-7458.1999.00468.x. S2CID 85069089.
Held, D. W.; Potter, D. A. (2003). "Characterizing toxicity of Pelargonium spp. and two other reputedly toxic plant species to Japanese beetles (Coleoptera: Scarabaeidae)". Environmental Entomology. 32 (4): 873–880. doi:10.1603/0046-225x-32.4.873.
Geraniums and Begonias: New Research on Old Garden Favorites (the March 2010 issue of Agricultural Research magazine.)
Ranger, C.M.; Winter, R. E.; Singh, A. P.; Reding, M. E.; Frantz, J. M.; Locke, J. C.; Krause, C. R. (2011). "Rare excitatory amino acid from flowers of zonal geranium responsible for paralyzing the Japanese beetle" (PDF). Proceedings of the National Academy of Sciences. 108 (4): 1217–1221. Bibcode:2011PNAS..108.1217R. doi:10.1073/pnas.1013497108. PMC 3029778. PMID 21205899.
Usherwood, P. N. R. (1994). "Insect glutamate receptors". Advances in Insect Physiology Volume 24. Advances in Insect Biochemistry and Physiology. Advances in Insect Physiology. 24. pp. 309–341. doi:10.1016/S0065-2806(08)60086-7. ISBN 9780120242245.
Garbuzov, Mihail; Ratnieks, Francis L. W. (2013). "Quantifying variation among garden plants in attractiveness to bees and other flower-visiting insects". Functional Ecology. 28 (2): 364–374. doi:10.1111/1365-2435.12178.
Martinou, A.F.; Papachristos, D.; Milonas, P.G. (2011). "Report of the Geranium Bronze Butter y, Cacyreus marshalli for mainland Greece". Hellenic Plant Protection Journal.
RHS A-Z encyclopedia of garden plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 978-1405332965.
"Gardening - Gardening Guides - Techniques - Taking pelargonium cuttings". BBC. 1970-01-01. Retrieved 2013-09-12.
CA grant 2704584, Hanes, Mitchell E., "Flower pigmentation in pelargonium hortorum", published October 29, 2013
Minimum Temperatures for Geranium Plants
Wilkinson 2007, p. 189.
Handlos, Wayne (2010). "Connections, Legacies, and Contributions:Liberty Hyde Bailey, Jr". Geraniums Online. Central Coast Geranium Society. Retrieved 3 August 2017.
Dauthenay 1897.
Amadio 2015.
Wilkinson 2007, Appendix 2: Horticultural Classification and Glossary.
PAGS 2015, About us.
PAGS 2015, International Register of Pelargonium Cultivars.
ISHS 2015, ICRA: Pelargonium and Geranium Society.
RHS 2015, Pelargonium (geranium).
PAGS 2015, Pelargonium Basics.
RHS 2015, Horticultural classification for Pelargonium L'Her. ex Aiton.
PAGS 2015, Horticultural symbols and terms.
"Pelargonium 'Chelsea Gem'". Royal Horticultural Society.
"Pelargonium 'Hindoo'". Royal Horticultural Society.
"Pelargonium ×hortorum". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 5 August 2017.
Hutchinson Farm: Zonal Geraniums
Hutchinson Farm: Rocky Mountain Geraniums
The University of Tennessee Gardens: Pelargonium x hortorum Rocky Mountain™ 'Dark Red'
"Pelargonium 'Sugar Baby'". Royal Horticultural Society.
Sweet 1822, Pelargonium ignescens.
Cornett, Peggy (2013). "Pelargonium fulgidum hybrid - Scarlet Unique Geranium". Monticello.org. Thomas Jefferson Encyclopedia. Retrieved 3 August 2017.
"Pelargonium 'Attar of Roses'". Royal Horticultural Society. Retrieved 25 January 2021.
"Pelargonium 'Citriodorum'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Dolly Varden'". Royal Horticultural Society. | access-date = 16 January 2021}}
"Pelargonium 'Frank Headley'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Fringed Aztec'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Gemstone'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Grace Thomas'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Joy'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Lady Plymouth'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Lara Candy Dancer'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Lara Starshine'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'L'Élégante'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Mabel Grey'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Mrs Quilter'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Radula'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Royal Oak'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Spanish Angel'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Sweet Mimosa'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Tip Top Duet'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium 'Voodoo'". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargonium tomentosum". Royal Horticultural Society. Retrieved 16 January 2021.
"Pelargoniums - An Herb Society of America Fact Sheet" (PDF). The Herb Society of America. 2006. Archived from the original (PDF) on 27 February 2012. Retrieved 20 December 2012.
"Pelargonium sidoides (African geranium)". WholeHealth Chicago. 2010-02-14.
"Apple Geranium". Natural Medicinal Herbs.
Saunders Currey, Geoffrey (1922). "The Colouring Matter of the Scarlet Pelargonium". J. Chem. Soc., Trans. 121: 319–323. doi:10.1039/CT9222100319.
Hunt, D. M.; K. S. Dulai; J. K. Bowmaker; J. D. Mollon (1995). "The chemistry of John Dalton's color blindness". Science. 267 (5200): 984–988. Bibcode:1995Sci...267..984H. doi:10.1126/science.7863342. PMID 7863342. S2CID 6764146.

Dalton, John (1798). "Extraordinary facts relating to the vision of colours: with observations". Memoirs of the Literary and Philosophical Society of Manchester. 5: 28–45.

Bibliography
Books

Bakker, F. T.; Culham, A. & Gibby, M. (1999). "Chapter16. Phylogenetics and diversification in Pelargonium". In Hollingsworth, P.; Bateman, R. & Gornall, R. (eds.). Molecular Systematics and Plant Evolution. CRC Press. pp. 353–374. doi:10.1201/9781439833278.ch16. ISBN 978-0-7484-0908-2.
Boddy, Kasia (2013). Geranium. London: Reaktion Books. ISBN 9781780230580. Retrieved 31 July 2015.
Butterfield, Harry Morton (1953). Geraniums and pelargoniums for the home garden. Berkeley: University of California. Retrieved 23 July 2015.
Lis-Balchin, Maria, ed. (2002). Geranium and pelargonium: the genera geranium and pelargonium. London: Taylor & Francis. ISBN 978-0-415-28487-5. Retrieved 12 July 2015.
Mabberley, David J (2013). "Pelargonium". Mabberley's Plant-Book (3 ed.). Cambridge University Press. p. 641. ISBN 978-1107782594. Retrieved 17 August 2014.
Taylor, Judith M. (2014). Visions of Loveliness: Great Flower Breeders of the Past. Ohio University Press. ISBN 9780804040624. Retrieved 23 July 2015.
van der Walt & Vorster (1971–1988). Pelargoniums of Southern Africa (3 vols). Illustrated by Ellaphie Ward-Hilhorst. Cape Town & Johannesburg: Purnell.
Wilkinson, Ann (2007). The Passion for Pelargoniums. How They Found Their Place in the Garden. Stroud: The History Press. ISBN 9780752496061. Retrieved 12 July 2015.

Historical

Dillenius, Johann Jakob (1732). Hortus Elthamensis seu Plantarum Rariorum ... (in Latin). London: Sumptibus Auctoris. Retrieved 26 July 2015.
Hortus Elthamensis on Gallica
Linnaeus, Carl (1753). Species Plantarum, ... (in Latin). Stockholm: Impensis Laurentii Salvii. doi:10.5962/bhl.title.669.
Sweet, Robert (1822). Geraniaceae: The Natural Order of Gerania. Volume I. Piccadilly: James Ridgeway. doi:10.5962/bhl.title.102247. hdl:2027/gri.ark:/13960/t61580v6m.
Dauthenay, Henri (1897). Les Géraniums (Pelargonium zonale & inquinans): description et culture ... (in French). Paris: Octave Doin. Retrieved 12 July 2015.
Bailey, L.H. (1906) [1900]. The Cyclopedia of American Horticulture (4 vols.) (5th ed.). New York: Macmillan. doi:10.5962/bhl.title.29309.
Bailey, L.H. (1919) [1900]. The Standard Cyclopedia of Horticulture (6 vols.) (3rd ed.). New York: Macmillan. doi:10.5962/bhl.title.23351.

Articles and theses

Aedo, Carlos & Garmendia, Félix Muñoz (Feb 1996). "Some Notes on the Sectional Nomenclature of Geranium (Geraniaceae)". Taxon. 45 (1): 104–106. doi:10.2307/1222593. JSTOR 1222593.
Bakker, Freek T.; Culham, Alastair; Pankhurst, Clive E. & Gibby, Mary (May 2000). "Mitochondrial and chloroplast DNA-based phylogeny of Pelargonium (Geraniaceae)". Am. J. Bot. 87 (5): 727–734. doi:10.2307/2656859. JSTOR 2656859. PMID 10811797. Retrieved 13 July 2015.
Bakker, Freek T.; Culham, Alastair; Hettiarachi, Priyani; Touloumenidou, Tasoula & Gibby, Mary (Feb 2004). "Phylogeny of Pelargonium (Geraniaceae) based on DNA sequences from three genomes". Taxon. 53 (1): 17–28. doi:10.2307/4135485. JSTOR 4135485.
Lalli, Jacqueline Yolande Yvette (2005). In Vitro Pharmacological Properties and Composition of Leaf Essential Oils and Extracts of Selected Indigenous Pelargonium (Geraniaceae) Species (PDF) (MPharm). University of the Witwatersrand. Retrieved 7 August 2017.
Röschenbleck, J; Albers, F; Müller, K; Weinl, S & Kudla, J (11 February 2014). "Phylogenetics, character evolution and a subgeneric revision of the genus Pelargonium (Geraniaceae)" (PDF). Phytotaxa. 159 (2): 31–76. doi:10.11646/phytotaxa.159.2.1.
van der Walt, J.J.A. (1979). "Notes on the nomenclature of Pelargonium Geraniaceae". Journal of South African Botany. 45: 377–380. Retrieved 14 July 2015.
van der Walt, J.J.A. & Vorster, P.J. (February 1981). "Typification of the Genus Pelargonium L'Hérit. (Fam. Geraniaceae)". Taxon. 30 (1): 307. doi:10.2307/1219408. JSTOR 1219408.

Societies

ISHS (2015). "International Society for Horticultural Science". Retrieved 13 July 2015.
RHS (2015). "Royal Horticultural Society". Retrieved 19 June 2015.
PAGS (2015). "The Pelargonium & Geranium Society". Retrieved 7 July 2015.
AGS (2014). "Australian Geranium Society". Retrieved 8 July 2015.
HSA (2015). "The Herb Society of America" (PDF). Archived from the original on 24 September 2015. Retrieved 12 July 2015.**
Amadio, Marisa (2015). "The Geraniaceae Group". Retrieved 13 July 2015.