Genus: 1; Piper; 450 species.
Region: Neotropics.
Habitat: open sites, along roads and forest edges, some in understory.
Botany: medium-size shrubs, mostly self-supporting, some herbaceous or lianescent shrubs.
Leaves: membranaceous, plinerved or sometimes pinnately nerved, basally unequal, different levels of pubescence, rarely glabrous.
Inflorescences: terminal, erect; tightly arranged, forming banding patterns; some species distally curved at anthesis curved as in
Piper aduncum.
Flowers 4 stamens.
TaxonomyMiquel described
Raduloideae as part of Artanthe clade. Most subsequent classifications like de Candolle and Trelease and Yuncker of Piper did not recognize
Raduloideae. Callejas included Radula within a much larger Steffensia clade. Tebbs recognized Radula as a distinct section of Piper. Molecular sequence data presented here provide strong support for the monophyly of Radula.
A number of subclades can be distinguished within Radula: Isophyllon and the Piper filistilum complex
Isophyllon subclade are medium- sized shrubs, self-supporting or sarmentose. Leaves are oblong or lanceolate, more or less coriaceous, pinnately nerved throughout, and basally obtuse or acute. Flowers are tightly arranged in the inflorescences, forming banding patterns. Inflorescences are erect and apiculate. Fruits are concrescent with the rachis. The Isophyllon clade has ∼120 species and it is most diverse in the Atlantic Forest and also in Central America.
Miquel described Isophyllon as a section of the Artanthe clade.
The Piper filistilum clade were previously included in the genus Trianaeopiper by Trelease. The clade has axillary inflorescences. The leaves are similar to Radula species, but with reduced axillary, sympodial branches that appear to be axillary inflorescences. Inflorescences do not have the typical banded pattern of Radula. The Piper filistilum complex is restricted to the Chocó Region in northwestern South America.
The Peltobryon clade has ± 90 species and is widespread in South America, especially the western Amazon and the eastern Andean slopes in Bolivia, Ecuador, and Perú. Peltobryon was first described as a genus by Miquel. They are shrubs or treelets in the forest understory. They occur from sea level to 2000 m in elevation. Leaves are pinnately nerved, secondary veins arise throughout the entire lamina, which is marginally ciliate, and often strongly glandular dotted. Leaves are glabrous or pubescent and then with branched hairs. Inflorescences are mostly erect, thick, and greenish in fruit. The anthers often exhibit prominent connectives protruding above the thecae and are glandular dotted. Floral bracts are marginally fimbriated with a central portion strongly glandular dotted. A banded pattern is apparent in some species. Fruits are oblong, exerted, sessile, fleshy and glandularly dotted, seeds are obovoid and apically depressed. Many species display large stylar projections and prominente stigmatic lobes.