The first information about this genus goes back to the 17th century. The Cape pelargoniums attracted the attention of many travellers during the time of early explorations along the coast. From 1660 the Cape of Good Hope offered shelter to vessels heading for the Far East.

Here they could stock up with water and provisions for the long journey. The crew often included a naturalist in charge of scientific exploration collecting botanical and zoological specimens for museum and botanical gardens. The first Pelargonium to arrive in Europe was probably P. triste brought by the English botanist John de Tradescant. It was described in 1633 by Thomas Johnson as "geranium indicum noctu odoratum" ( an Indian Geranium that is nocturnally scented) ,though it was a typical South African species (it was probably first taken from there via India on the voyage to England). In 1652 the Duch East India Company founded a colony at Table Bay. In the following years they played an important role in bringing many Pelargonium species to our continent, among these P. peltatum and P. zonale, progenitors of many current varieties, and P. cucullatum. Soon these plants became noticed by many European plantsmen and inspired lively interest amongst artists and botanists of the time. Botanical gardens and wealthy garden owners began to encourage these African species. In 1732 the botanist J. H. Dillenius described and illustrated some "African Geraniums" in his work Hortus Elthamensis. He mentioned P. inquinans, P. vitifolium, P. carnosum, P. papilionaceum, P. cucullatum, P. fulgidum and P. odoratissimum. Other descriptions can be found in the work Rariorum Africanorum plantarum (1738) by the Dutch botanist J. Burman, illustrated by H. Cladius who painted these plants during his travels in the Cape. (v.d. Walt, 1977; Esser, 1977; Pizzetti, 1988).

It is interesting to note that during the 18th century up till the time of Linnaeus, all these species were included in the genus Geranium; not till 1789 did the French botanist Charles-Louis L'Héritier de Brutelle, in his manuscript "Compendium Generalogium" use the name Pelargonium, describing about 80 species (v.d. Walt, 1977).

In 1802 the Cape Colony became English and from that moment a great number of examples were brought to Great Britain, by then they were much in demand because they were beginning to be cultivated in protected places and new hybrids created. Pelargoniums reached the height of their popularity in the Victorian era and this lasted until the start of the First World War when it was forbidden to cultivate ornamental plants in greenhouses in England. In the rest of Europe there was also interest in these plants especially in France, where many varieties were introduced by Lemoine and Bruant, and in Germany thanks to the work of Burger and Faiss (Pizzetti, 1998).

Today, Pelargonium, besides being a very popular ornamental plant also has other uses: P. radens, P. graveolens, P. capitatum and P. odoratissimum are used for the production of essential oils (geraniol and citronello) often as a substitute for the much more expensive version obtained from roses. Others species such as P. triste and P.antidysentericum have long been recognised for their healing property against dysentery and ulcers (v.d. Walt, 1977; Grieve, 1944).

Pelargoniums show remarkable morphological differences between the various species ( such as the insertion and the shape of the leaves.); this has therefore often created difficulties in the description and classification of these plants. In his work "Geraniaceae" (1820-1830) R. Sweet distinguished the genera Geranium, Erodium, Monsonia, Sarcocaulon and Pelargonium, breaking down the last genus into the sections Campylia, Hoarea, Jenkinsonia.

In 1824 the first volume of "Prodromus systematis naturalis regni vegetabilis" by A.P. De Candolle was published, in which the Swiss botanist divided the genus Pelargonium into 12 sections. Another contribution came from C.F. Ecklon and K.L.Zeyher who in their work "Enumeratio plantarum Africae Australis" (1835), described many new species of Pelargonium. In 1842 the botanists W.H.Harvey and O.W.Sonder published their first volume of "Flora Capensis" in which the Geraniaceae family was dealt with; they described 163 species of Pelargonium in 15 sections (some of them already singled out by Sweet): Hoarea, Seymouria, Polyactium, Otidia, Ligularia, Jenkinsonia, Myrrhidium, Peristera, Campylia, Dibrachya, Eumorpha, Glaucophyllum, ciconium, Cortusina and Pelargium.

They used the physionomy of the plants and the characteristics of the leaves and flowers as a means of diagnosis. These criteria of classification was adopted by the German botanist R.Knuth: his work on Geraniaceae were published by Engler in 1912 "Das Pflanzenreich" (v.d. Walt, 1977).

At present the sections of the genus Pelargonium still mainly reflect their origin from Sweet and Harvey and Sonder; but modificatios have been made in the light of palynology, biochemistry and cromosone studies. (Kuhlman, 1998).

Section Campylia (Sweet) DC
The species found in this section are generally geophytic and creep horizontally underground. The leaves are oval or lanceolate, their stalks are much longer than the lamina with fleshy stipules at their base. The flowers have obovate upper petal much longer than the lower ones. Found in: P.capillare (Cav.) Willd., P. coronopifolium Jacq., P. elegans (Andr.) Willd., P. oenothera (L.f.) Jacq., P. ovale (Burm. F.) L'Hérit., P. tricolor Curt..

Section Chorisma Albers.
This section which has recently been described includes (on the basis of the karyotype and DNA sequencing ) some species that formally appeared under Ligularia and Jenkinsonia, amongst which P. exhibens Vorster and P. tetragonum (L.f.) L'Hérit. (Albers, 1995; Kuhlman, 1998).

Section Ciconium (Sweet) Harv.
This section includes shrubs or subshrubs species with thick fleshy stems. The leaves are usually ovate, cordate or reniform with evident veins. The flowers have five petals of uniform colours. The section includes the species from which zonal and ivy-leaved pelargoniums are derived. Some of the species were originally classified in the section Eumorpha, now abolished. We find: P. acraeum R.A. Dyer, P. alchemilloides (L.) L'Hérit. (ex sect. Eumorpha), present not only in South Africa but also in Lesotho, Zimbabwe, Tanzania, Kenya, Ethiopia and Somalia, P. inquinans (L.) L'Hérit., P. peltatum (L.) L'Hérit., P. transvaalense Knuth, P. zonale (L.) L'Hérit..

Section Cortusina DC.
The species in this section are subshrubs with rather short succulent stems, often covered in persistent stipule giving the impression of thoms. The leaves are cordate, palmate, lobate or reniform and nearly always very tomentose; the flowers produce five petals of which the two upper are bigger than the lower. Some species of this section are included in a separate section Reniformia. We find: P. crassicaule L'Hérit., P. echinatum Curt., P. magenteum J.J. v.d. Walt.

Section Glaucophyllum Harv.
In this section we find subshrubby species with simple fleshy or trilobate leaves with persistent often spiny stalks. The flowers have five enequal petals. We find: P. fruticosum (Cav.) Willd., P. grandiflorum (Andr.) Willd., P. laevigatum (L.F.) Willd., P. lanceolatum (Cav.) Kern., P. patulum Jacq., P. ternatum (L.f.) Jacq.

Section Hoarea DC.
This is named in honour of Sir R. Colt Hoare. It includes about 40 species. They are acaulescent in habit with 1-3 oval or cylindrical tubers. The flowers usually have five petals and five fertile stamens. The species are very decorative but difficult to propagate and they have a long period of dormancy. The section includes Seymouria (now abolished). Those of major interest are: P. appendiculatum (L.f.) Willd., a protected and very rare species, P. asarifolium (Sweet) G. Don (ex sect. Seymouria), P. auritum (L.) Willd., P. incrassatum (Andr.) Sims., P. leipoldtii Knuth, P. namaquense Knuth, P. oblongatum E. Mey. Ex Harv..

 Section Isopetalum (Sweet) DC.
At the moment this section has only one species: P. cotyledonis (L.) L'Hérit, endemic to the island of St Helena.

Section Jenkinsonia (Sweet) Harv.
The species in this section are subshrubby with the stems being woody or succulent at the base. The leaves are usually palmate and the flowers have four or five petals. The two upper petals are much bigger and more striking than the lower. Examples: P. antidysentericum (Eckl. & Zeyh.) Costel., P. praemorsum (Andr.) Dietr..

Section Ligularia (Sweet) Harv.
Many of the species included in this section are succulents, they have branched stems, usually woody at the base; the leaves are pinnate and the flowers have five enequal petals. There are substantial differences between the species depending firstly on their habitat, those in areas where there is only winter rainfall or areas where the rain is more evenly spread; secondly on their flowering period which can be just in winter or summer or prolonged up to 10 months of the year. From the species of South Africa are: P. articulatum (Cav.) Willd., P. barklyi Scott Elliot, P. crassipes Harv., P. desertorum Vorster, P. fulgidum (L.) L'Hérit. (included before in section Polyactium), P. hystrix Harv., P. oreophillum Schelechter, P. sericifolium v.d. Walt, P. stipulaceum (L.f.) Willd., P. tenuicaule Knuth, P. xerophyton Schlechter ex Knuth.

Section Myrrhidium DC.
The name of this section is derived from the similiarity of the plants to Commiphora myrrha ( Burseraceae) from which myrrh is obtained. Subshrubby species as well as annuals are included, they have pinnate leaves and flowers with four or five petals of which the upper two are much bigger than the lower. The calyx has very evident veins on the sepals. Examples: P. longicaule Jacq. var. angustipetalum Boucher, P. longicaule Jacq. var. longicaule, P. multicalule Jacq. subsp. multicaule, P. multicaule Jacq. subsp. subherbaceum (Knuth) v.d. Walt, P. myrrifolium (L.) L'Hérit var coriandrifolium (L.) Harv., P. suburbanum Clifford ex Boucher subsp. bipinnatifidum (Harv.) Boucher, P. suburbanum Clifford ex Boucher subsp. suburbanum.

Section Otidia (Lindl.) Harv.
This section's name is derived from the characteristic shape of the flowers in which the upper flower produces a sort of ear at its base. The species in this section produce dense succulent stems often gnarled; the leaves are fleshy and pennati-partite. The majority of these species are found on the edge of the River Orange, on the border with Namibia, where there are long periods of drought and only winter rains. Recorded in: P. alternans Wendl., P. carnosum (L.) L'Hérit, P. crithmifolium J.E. Smith, P. klinghardtense Knuth, P. laxum (Sweet) G. Don.

Section Pelargonium (DC.) Harvey
This section, originally wrongly named Pelargium, contains shrubby and subshrubby species with very branched stems. The leaves are usually palmately lobate or cordate often tomentose and perfumed; the flowers produce five petals of which the two upper are more showy than the lower. Recorded in: P. capitatum (L.) L'Hérit., P. cordifolium (Cav.) Curt., P. cucullatum (L.) L'Hérit. subsp. cucullatum (L.) L'Hérit. subsp. strigifolium Volschenk, P. cucullatum (L.) L'Hérit. subsp. tabulare Volschenk, P. glutinosum (Jacq.) L'Hérit., P. greytonense v.d. Walt, P. hermannifolium (Berg.) Jacq., P. hispidum (L.f.) Willd., P. pseudoglutinosum Knuth, P. radens H.E.Moore, P. ribifolium Jacq., P. scabrum (Burm. F.) L'Hérit.

Section Peristera DC
The majority of the species in this section are annuals. Their habit is similar to Geranium and Erodium; the leaves are palmate or pinnate, the flowers are small with petals and sepals of equal size. Examples: P. grossularioides (L.) L'Hérit..

Section Polyactium (Eckl. & Zeyh.) DC.
The name of this section refers to the star shaped inflorescences. The flowers are usually strongly scented by night. Their petals are characterised by a long spur. The majority of the species produce underground tubers and lobed or pinnately divided leaves. The section includes about twenty species some of which are: P. bowkerii Harv., P. gibbosum (L.) L'Hérit., P. lobatum (Burm. F.) L'Hérit., P. luridum (Andr.) Sweet, P. pulverulentum Colv. ex Sweet, P. schizopetalum Sweet, P. triste (L.f.) L'Hérit.

Section Reniformia (Knuth) Dreyer
The characteristic that unites the species of this section, many of which were previously included in other sections, is the reniform shape of the leaves; other common characteristics are the form of the stipule and the long persistent stalks and the branch like inflorescences. The plants usually have a caespitose appearance. Examples: P. abrotanifolium (L.f.) Jacq. (ex sect. Ligularia), P. album v.d. Walt, P. dichondrifolium DC. (ex sect. Cortusina), P. fragrans Willd. (ex sect. Cortusina), P. ionidiflorum (Eckl. & Zeyh.) Steudel (ex sect. Ligularia), P. odoratissimum (L.) L'Hérit. (ex sect. Cortusina), P. reniforme Curt. (ex sect. Cortusina), P. sidoides DC. (ex sect. Cortusina).

Section Subsucculentia v.d. Walt.
As in the case of section Chorisma, some species previously included in section Ligularia are now included in this section. Examples: P. grandicalcatum Knuth, P. otaviense Knuth, P. karooicum Compton & Barnes, P. spinosum Willd. (initially included in the section Glaucophyllum) (v.d. Walt, 1995; Kuhlman, 1998).