Nearly 1,500 different species of begonias exist around the world. In botanical taxonomy, a species is the simplest classification of plants sharing similar physical characteristics that can successfully inter-breed among each other. Variations among different species of begonias exist, such as flower color, leaf shape or size, but all begonias share a common flower morphology. The general phrase "Begonia species" simply implies the plant in question is a begonia, but further investigation is necessary to find its specific species identity.
Begonia species are found across much of the tropical and subtropical regions of the world at many different altitudes and habitats. They are naturally found in tropical America, sub-Saharan Africa, tropical southern and southeastern Asia. No begonias are native to tropical Australia. According to the American Begonia Society, new wild begonia species are still being discovered today.
In the late 1600s, the French botanist Charles Plumier named and illustrated six new tropical plant species in the Caribbean. Plumier decided to name this new group of plants Begonia in honor of the governor of the French Antilles from 1682 to 1685, Michel Begon. The name Begonia was adopted by Carl Linneaus himself when he published his "Species Plantarum" in 1753, according to Mark Tebbit, author of "Begonias."
Asymmetrically shaped leaves that are arranged in an alternating pattern on fleshy jointed stems and ornate flowers comprise the primary, quick characteristics to surmise the plant is a begonia species. Nature always provides examples that do not so readily conform to man-made classification systems. There is huge diversity in leaf shapes, plant forms and flower colors, although most wild begonia species naturally produce white or pink flowers, with some displaying red, orange or yellow ones. Begonia flowers are either male or female in gender. The flowers are described as having tepals rather than petals. A tepal is a modified leaf that looks indistinguishable between a petal and a sepal. Begonia flowers can have two, three, four, five tepals, but some native to South America possess as many as 11, according to "Begonias." Only female flowers yield fruited seeds, and the fruits are among the most important organs for botanists to identify begonia species.
The vast diversity of begonia species and their characteristics led horticulturists at the American Begonia Society to group begonias into eight generalized type categories. From a gardening and enjoyment standpoint, the eight categories quickly distinguish among habits or genetic origins. Cane, shrub, rhizomatous, tuberous, semperflorens-cultorum, rex-cultorum, trailing/scandent and thick-stemmed comprise the American type system. In Europe, where more hybrid begonias are grown than species, they group them into any of five types: Elatior, Lorraine, semperflorens-cultorum, tuberous and foliage.
Begonias are all members of the begonia family, Begoniaceae. One other botanical genus, with only one species is also in the begonia family: Hillebrandia sandwicensis, from Hawaii. After 2003, the genus Symbegonia with 12 plant species was reclassified and lumped into the general Begonia classification. According to "Begonias," the begonia family is closely related to the cucumber family (Cucurbitaceae); datisca family (Datiscaceae); and the tetrameles family (Tetramelaceae).