Piper L.

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

A pantropical genus of 1000–1500 species, with the centre of diversity in the Neotropics. Depending on the species limits used, New Guinea has c. 20–60 native species, many of which are climbers (see Gardner 2013). Non-native species which are found in New Guinea include the economically important Piper betle L. (the leaf and inflorescence are used when chewing betel nut) as well as the widespread invasive species, P. aduncum L.

Morphology General Habit

Herbs, climbers, shrubs and trees to 8 m tall, stems often thickened at the nodes

Morphology General Indumentum

Indumentum when present of simple hairs

Morphology Leaves Stipules

Stipules minute, adnate to petiole, amplexicaul or absent

Morphology Leaves

Leaves simple, alternate, distichous, often aromatic, petioles present, sometimes sheathing stem, membranous to coriaceous, base rounded or cordate, sometimes unequal, margins entire, venation usually acrodromous or camptodromous. Inflorescences leaf-opposed, spikate, often pendulous

Morphology Reproductive morphology Flowers

Flowers unisexual and plants monoecious or dioecious, lacking perianth, minute, each subtended by a bract; stamens 2–6, free; ovary superior, unilocular, 1 ovule per locule, placentation basal, style simple, stigmas 2–5

Morphology Reproductive morphology Fruits

Fruits drupaceous, sometimes enclosed by the floral bract or the fleshy inflorescence axis

Ecology

Piper are often pioneer species of disturbed or open habitats and are found in New Guinea from sea level to subalpine habitats above 3500 m. The ubiquitous betel leaf (P. betle) is a climber. The invasive shrubby species P. aduncum was probably introduced in World War II and is common throughout New Guinea, particularly in early successional or disturbed areas and old garden sites, but does not seem to be able to colonise primary rain forests. It is widespread in New Guinea from sea level to about 2000 m.

Recognition

The genus can be recognised by the thickened nodes, the alternate, distichous leaves and the leaf-opposed, spicate inflorescences of minute flowers.

Piperaceae, M.A. Diniz. Flora Zambesiaca 9:2. 1997

Morphology General Habit

Erect, scandent or climbing shrubs, or sometimes lianes.

Morphology Stem

Stems often hollow, jointed at the nodes.

Morphology Leaves

Leaves alternate, sometimes asymmetrical at the base, membranous or coriaceous.

Morphology Leaves Stipules

Stipules adnate to the petiole, soon caducous.

Morphology Reproductive morphology Inflorescences

Inflorescences axillary or leaf-opposed, pedunculate, with flowers in dense cylindrical spikes, rarely racemose.

Morphology Reproductive morphology Flowers

Flowers hermaphrodite or unisexual; plants monoecious or dioecious.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 2–4(6) in the Flora Zambesiaca area; filaments short; anthers basifixed with the thecae usually distinct.

Morphology Reproductive morphology Flowers Gynoecium Pistil

Ovary ± ovoid to subglobose; stigmas 2–4(5), erect or recurved, sessile or on a short style.

Morphology Reproductive morphology Fruits

Fruit a ± globose 1-seeded drupe, sessile, rarely pedunculate.

Morphology Reproductive morphology Seeds

Seed sub-globose; testa thin; endosperm and perisperm hard.

George R. Proctor (2012). Flora of the Cayman Isands (Second Edition). Royal Botanic Gardens, Kew

Morphology General Habit

Shrubs or small trees (rarely vines), with the branches often jointed at the nodes

Morphology Leaves

Leaves alternate, often unequal-sided at the base, sometimes with pellucid dots, the venation pinnate or palmate

Morphology Reproductive morphology Inflorescences

Spikes opposite the leaves, typically solitary and simple

Morphology Reproductive morphology Flowers

Flowers usually perfect, numerous; stamens 2–6; ovary sessile; stigmas 2–4, sessile or on a short and thick style

Morphology Reproductive morphology Fruits

Fruit variable, usually small.

Distribution

A vast genus of more than 1,000 species.

Ecology

The chief economic species is the black pepper, Piper nigrum, a subwoody vine. Often numerically important in the understory of tropical vegetation, a few weedy species ubiquitous in clearings of many areas, chiefly where rainfall is high.