Pelargonium, a genus of plants of the natural order Geraniaceæ, including many of the most favourite greenhouse flowers, to which the old generic name Geranium is often popularly given. The characters which distinguish pelargonium from geranium, as now restricted by botanists, are given in the article GERANIUM. The species are numerous, and mostly natives of the Cape of Good Hope, of certain other parts of South Africa, and a few are natives of the Canary Islands. Some of them are herbaceous and some are stemless; most of them are half-shrubby. Some have tuberous root-stocks. The leaves exhibit great variety in form, division, &c. The flowers always adhere to a certain type in form, but with great variety in size, colour, &c.; they are always in stalked umbels, which arise from the axils of the leaves, or in the stemless kinds from the midst of the leaves. In no genus has the art of the gardener produced more striking results than in this; and the number of beautiful hybrids and varieties is very great, some of them excelling in beauty any of the original species. Some species not possessing much beauty of flower are cultivated for the grateful odour of their leaves, which in some resembles that of roses, in others that of apples, lemons, &c.; whilst that of many species is rather unpleasant. The cultivation of pelargoniums is similar to that of other Geraniaceæ (see GERANIUM). A few of the species endure the open air in the south of England; many are planted out in summer even in Scotland. Water must be liberally supplied to pelargoniums during the time of flowering; but no plants more strongly require a period of rest, and water must then be very sparingly given.
The shrubby and sub-shrubby kinds are easily increased by cuttings either of the branches or the roots, stout pieces of the latter being the most fit for the purpose. Sandy soil and very moderate supplies of water are requisite till the cuttings are rooted, when richer soil and a more liberal supply of water are needed. The tuberous-rooted species are increased by cuttings of the roots and by seed.