The families of flowering plants

L. Watson and M.J. Dallwitz

Plagiopteraceae Airy Shaw

~ Celastraceae, Flacourtiaceae.

Habit and leaf form. Lianas (of combretaceous or malpighiaceous aspect, shortly ferrugineously stellate-pubescent); laticiferous. Climbing. Leaves opposite; membranous; simple. Lamina entire. Leaves exstipulate. Vernation conduplicate.

General anatomy. Plants with laticifers (their contents rubberlike). The laticifers in leaves and in stems.

Leaf anatomy. Hairs present. Complex hairs present; ferrugineous, stellate.

Axial (stem, wood) anatomy. The vessels with vestured pits (the vestures ‘rudimentary', Jansen et al. (2000)).

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in umbels and in panicles. The ultimate inflorescence units cymose. Inflorescences many-flowered, sub-umbelliform aggregates of thyrsiform groups. Flowers small; very fragrant; regular. Free hypanthium absent.

Perianth with distinct calyx and corolla; 6, or 8, or 10; 2 whorled; isomerous. Calyx (3–)4(–5); 1 whorled; gamosepalous (small, shortly united below); regular; open in bud. Corolla (3–)4(–5); 1 whorled; polypetalous; valvate (externally pubescent); regular (and revolute).

Androecium 30–100 (‘many’). Androecial members maturing centrifugally; free of the perianth; free of one another; 2 whorled (‘biseriate’). Androecium exclusively of fertile stamens. Stamens 30–100 (‘many’); polystemonous; filantherous (the filaments filiform-subclavate). Anthers small, more or less horizontal; dehiscing transversely; four locular; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer; of the ‘dicot’ type. Tapetum glandular (the cells becoming 2–4 nucleate). Pollen grains 3-celled.

Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 3 locular; sessile. Gynoecium stylate. Styles 1 (elongate, subulate); apical. Stigmas 3 (‘style slightly three-lobed’). Placentation basal to axile. Ovules 2 per locule; ascending; collateral; anatropous; bitegmic (inner and outer integuments 3 and 4 cells thick, respectively); weakly crassinucellate (parietal tissue one-layered). Outer integument contributing to the micropyle. Endothelium differentiated (nucellar tissue disintegrating early). Embryo-sac development Polygonum-type. Antipodal cells formed; proliferating (to 15–20 cells); ephemeral. Synergids pear-shaped. Hypostase absent.

Fruit non-fleshy; dehiscent; a capsule (turbinate). Capsules with three apical, spathulate wings, finally septicidal. Micropyle zigzag.

Geography, cytology. Paleotropical. Tropical. Burma.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Malvales. Cronquist’s Subclass Dilleniidae; Violales. APG III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Malpighiales (as a synonym of Celastraceae).

Species 1 (Plagiopteron suaveolens). Genera 1; only genus, Plagiopteron.

General remarks. This description is rather inadequate, save for Ya Tang’s (1994) account of the embryology. It differs conspicuously from that of Celastraceae (q.v.) in the polystemony and septicidal capsules, seemingly also in the zigzag seed micropyle.

Illustrations. • Plagiopteron suaveolens: guang xi zhi wu zhi (2005).

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: 15th April 2018.’.