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The families of flowering plants

L. Watson and M. J. Dallwitz

Peperomiaceae (Miq.) Wettst.

~ Piperaceae.

Habit and leaf form. Sub- shrubs, or herbs. Plants more or less succulent. Self supporting, or epiphytic (commonly). Mesophytic. Leaves alternate, or opposite, or whorled; when alternate, spiral; more or less fleshy; 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 exstipulate. Lamina margins entire. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral. Leaves with ‘pearl glands’ (sometimes), or without ‘pearl glands’. Hydathodes commonly present, or absent. Stomata present; usually mainly confined to one surface (abaxial); anisocytic, or cyclocytic. Hairs present (but never forming a dense covering); eglandular and glandular; mostly multicellular. Multicellular hairs multiseriate. Adaxial hypodermis present, or absent. Lamina with secretory cavities, or without secretory cavities (?). Secretory cavities if present, containing mucilage. The mesophyll with spherical etherial oil cells (usually with secretory cells having translucent or brown, often oily contents, these sometimes appearing as transparent or opaque dots); containing crystals. The crystals druses, or solitary-prismatic (acicular). Minor leaf veins without phloem transfer cells (Peperomia).

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Nodes penta-lacunar, or multilacunar (with five or more traces). Primary vascular tissues disposed monocot-like, and consisting of scattered bundles (see illustration), or comprising two or more rings of bundles; collateral. Internal phloem absent. Medullary bundles present. Secondary thickening developing from a conventional cambial ring, or anomalous. The anomalous secondary thickening from a single cambial ring.

The vessel end-walls scalariform, or simple. The axial xylem without fibre tracheids; with libriform fibres; including septate fibres, or without septate fibres.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in spikes (and spadices). Inflorescences terminal, or axillary, or leaf-opposed; with flowers aggregated into spikes or spadices. Flowers bracteate (the bracts succulent); minute to small.

Perianth absent.

Androecium 2. Androecial members united with the gynoecium (adnate to its base), or free of the gynoecium; all equal; free of one another to coherent; often more or less 1 adelphous (the filaments joined at the base). Androecium exclusively of fertile stamens. Stamens 2. Anthers dehiscing via longitudinal slits (via one slit); extrorse; bilocular, or unilocular (by confluence); bisporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. Anther wall initially with one middle layer, or initially with more than one middle layer (1–2); of the ‘monocot’ type. Tapetum glandular. Pollen grains aperturate to nonaperturate; when detectably aperturate, 1 aperturate; sulcate; 2-celled.

Gynoecium 1 carpelled. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel 1 ovuled. Placentation basal. Stigmas dry type; non-papillate; Group II type. Ovules orthotropous; unitegmic; crassinucellate. Embryo-sac development Peperomia-type. Polar nuclei fusing prior to fertilization. Endosperm formation cellular. Embryogeny piperad.

Fruit fleshy to non-fleshy. The fruiting carpel indehiscent; drupaceous, or baccate. Gynoecia of adjoining flowers combining to form a multiple fruit, or not forming a multiple fruit. Fruit 1 seeded. Seeds scantily endospermic. Perisperm present (copious). Embryo rudimentary at the time of seed release.

Physiology, phytochemistry. CAM. CAM recorded directly in Peperomia. Ellagic acid absent (Peperomia). Sieve-tube plastids S-type.

Geography, cytology. Temperate to tropical. Pantropical, subtropical and warm temperate. X = 11(?).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Nymphaeiflorae; Piperales. Cronquist’s Subclass Magnoliidae; Piperales. APG 3 core angiosperms; Superorder Magnolianae; Order Piperales (as a synonym of Piperaceae).

Species 1000. Genera 4; Manekia, Peperomia, Piperanthera, Verhuellia.

General remarks. Distinguishable from Piperaceae sensu stricto (q.v.) by exstipulate leaves, bisporangiate anthers and monomerous gynoecium with unitegmic ovules, and the compiled data also suggest differences in stigma structure and the pattern of embryo sac development.

Illustrations. • Peperomia resediflora: Bot. Mag. 108 (1882). • Peperomia argyreia (as arifolia var.): Bot. Mag. 93 (1867). • Technical details: Peperomia. • Transverse leaf sections and hydathodes of P. incana and P. pereskiaefolia, with pearl gland of Artanthe (= Piper, Piperaceae): Solereder, 1908. • TS stem of Peperomia incana, with scattered vascular bundles (with stems of Piperaceae spp.); Solereder, 1908.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 19th October 2016.’.