Family Piperaceae

Piperaceae C.A. Agardh

Excluding Peperomiaceae

Habit and leaf form. Shrubs, or lianas, or trees (small); bearing essential oils. Plants succulent, or non-succulent. Self supporting, or climbing. Stem growth conspicuously sympodial (often), or not conspicuously sympodial. Mesophytic. Leaves alternate; spiral; ‘herbaceous’, or fleshy; petiolate; sheathing. Leaf sheaths not tubular; with free margins. Leaves gland-dotted, or not gland-dotted; aromatic; simple. Lamina entire; pinnately veined, or palmately veined (or pinnate-palmate); cross-venulate. Leaves stipulate. Stipules intrapetiolar (adnate). Lamina margins entire. Leaves without a persistent basal meristem.

Leaf anatomy. Hydathodes commonly present. Stomata present; cyclocytic, or anisocytic.

Adaxial hypodermis commonly present. Lamina dorsiventral. The mesophyll with spherical etherial oil cells.

Stem anatomy. Cork cambium present; initially superficial. Nodes tri-lacunar to multilacunar (with three to five or more traces). Primary vascular tissue in scattered bundles. Medullary bundles present. Internal phloem absent. Secondary thickening developing from a conventional cambial ring to anomalous; from a single cambial ring. ‘Included’ phloem absent. Xylem without fibre tracheids; with libriform fibres (sometimes septate). Vessel end-walls scalariform, or simple. Wood storied to not storied; parenchyma paratracheal. Sieve-tube plastids S-type.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in spadices or in spikes. Inflorescences axillary, or leaf-opposed (usually), or epiphyllous; in spikes or spadices — these simple or umbellate. Flowers bracteate; minute to small.

Perianth absent.

Androecium 1–10. Androecial members united with the gynoecium (adnate to its base), or free of the gynoecium; free of one another to coherent; often more or less 1 adelphous (the filaments joined at the base). Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, in the form of arrested stamens. Stamens 1–10. Anthers dehiscing via longitudinal slits (via two slits); extrorse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. Anther wall initially with one middle layer, or initially with more than one middle layer (1 or 2); of the ‘monocot’ type. Tapetum glandular. Pollen grains aperturate to nonaperturate; when detectably aperturate, 1 aperturate; sulcate; 2-celled.

Gynoecium (2–)4 carpelled. The pistil 1 celled. Gynoecium syncarpous; synstylovarious; superior. Ovary 1 locular. Stigmas 1–5; dry type; papillate; Group II type. Placentation basal. Ovules in the single cavity 1; ascending; orthotropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Fritillaria-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; proliferating. Synergids poorly differentiated. Endosperm formation cellular, or nuclear. Embryogeny piperad.

Fruit fleshy; indehiscent; a berry. Gynoecia of adjoining flowers combining to form a multiple fruit. Fruit 1 seeded. Seeds scantily endospermic. Perisperm present (copious). Embryo rudimentary at the time of seed release.

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Not cyanogenic. Alkaloids present (nearly always), or absent. Iridoids detected (dubiously), or not detected. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent (2 genera). Saponins/sapogenins present (?), or absent. Aluminium accumulation demonstrated, or not found. CAM. Anatomy non-C4 type (Piper).

Geography, cytology. Sub-tropical to tropical. Pantropical. X = 12(?).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Nymphaeiflorae; Piperales. Cronquist’s Subclass Magnoliidae; Piperales. APG 3 core angiosperms; Superorder Magnolianae; Order Piperales.

Species 2000. Genera 7, or 8; Circaeocarpus (= Zippelia), Lindeniopiper, Ottonia, Piper, Pothomorphe, Sarcorhachis, Trianaeopiper, Zippelia (~ Piper).

Economic uses, etc. Piper nigrum is the source of black and white peppercorns (ripe and unripe, respectively); others are widely grown as houseplants.

Illustrations.
• Technical details (Piper sensu lato).
• Technical details: Piper (Thonner).
• Piper (fruiting inflorescence).