1. Hibiscus - The Genus

Malvaceac, a family of plants noted both for its economic and horticultural importance, includes such genera as Gossypium (the cottons), Althaea (the hollyhocks), Abutilons (Chinese lanterns) and of course Hibiscus

Probably the largest and certainly the most variable with respect to its vegetative and floral expression, as well as its adaptation to diverse habitats, the genus Hibiscus contains plants that vary front small annual or perennial herbs, undershrubs and shrubs to small trees. Hibiscus is derived from an ancient Greek word hibiskos which Dioscorides, a Greek physician of the first century, used for the plant commonly known as marsh-mallow, In 1735 when Carl Linnaeus described the marsh-mallow, instead of using the old name he chose a different name – Althea. Later, in 1737, he gave the name Hibiscus to a close relative to the marsh-mallow

The leaves of the hibiscus are simple and alternate. Their shape and size vary greatly, often even on the same branch. They can be entire, but more often they are lobed or deeply divided The floral structure of five petals surrounding a central staminal column is interesting. As well as the five petals, each flower has five sepals, an ovary consisting of five carpels, and numerous stamens. For most of their length the filaments of the stamens are joined together to form the staminal column, through the centre of which passes the single style. The style in turn ends in five stylar branches with stigmas at their tips, one for each of the five carpels in the ovary. These branches project from the end of the column in most exotic garden hibiscus. However, in Australian native hibiscus the stylar branches lie close together and do not spread as wide.

Hibiscus are distributed primarily through tropical and sub-tropical regions of the world, but a few species are found in temperate zones. Their habitats may range from mangrove swamps to coastal and inland marshes, desert, savannah or woodlands The number of species in the genus is difficult to estimate. The most recent comprehensive treatment of the genus recognised 197 species in twelve sections. This was by Hochreutiner in 1900. Taxonomic concepts have changed considerably since then and some species Hochreutiner placed in synonymy are now considered distinct, suggesting that 250 is not an unreasonable estimate of the number of species of hibiscus.

With such a large number of showy flowered species available it may seem surprising that more species of hibiscus are not encountered in cultivation, but this is understandable as the majority of the species in the genus are tender shrubs suitable for cultivation in tropical and sub tropical areas only. We shall deal only with the popular species grown commercially and encountered by most gardeners, beginning with the most important group of all, Hibiscus rosa sinensis.