The families of flowering plants

L. Watson and M. J. Dallwitz

Rhoipteleaceae Hand.-Mazz.

~ Juglandaceae.

Habit and leaf form. Herbs; probably bearing essential oils; resinous. Leaves deciduous; alternate; petiolate; non-sheathing; aromatic; compound; impari- pinnate. Lamina pinnately veined; cross-venulate. Leaves stipulate. Stipules small, caducous. Lamina margins denticulate.

Leaf anatomy. Stomata present; anomocytic. Hairs present; eglandular and glandular. Complex hairs present; basally embedded, glandular, peltate. Lamina without secretory cavities. The mesophyll without etherial oil cells.

Axial (stem, wood) anatomy. Secretory cavities absent. Cork cambium present. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. The axial xylem with vessels.

The vessel end-walls oblique; scalariform. The axial xylem with fibre tracheids. The parenchyma mostly paratracheal (vasicentric). ‘Included’ phloem absent.

Reproductive type, pollination. Plants hermaphrodite, or gynomonoecious (the flowers hermaphrodite and female (?), hermaphrodite and sterile, or the reduced members abortive). Pollination anemophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in catkins. The ultimate inflorescence units cymose (the flowers in bracteate dichasial triplets, the central member of each triplet hermaphrodite, the laterals pistillate but (usually or always?) sterile, or abortive). Inflorescences aments of dichasial triplets, clustered into large, nodding, terminal panicles. Flowers small (and inconspicuous). Free hypanthium absent. Hypogynous disk absent.

Perianth of the perfect flowers sepaline (the corolla absent); 4; 2 whorled (2+2); isomerous; persistent. Calyx 4; 2 whorled (2+2); polysepalous (the sepals small, scarious); persistent; non-accrescent; imbricate.

Androecium of the hermaphrodite flowers 6. Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens 6; shortly filantherous (the filaments persistent). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; bilocular; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; 3(–4) aperturate; colporate (with short colpi and large pores).

Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; synovarious; superior. Ovary 2 locular (below, but unilocular above, the partition falling short of the top). Gynoecium stylate. Styles 2; free; apical. Stylar canal present. Stigmas 2. Placentation axile. Ovules 1 per locule (but in only one locule of each pair, the other being sterile); ascending; hemianatropous to anatropous; bitegmic; crassinucellate. Endosperm formation nuclear.

Fruit non-fleshy; indehiscent; a samara (a two-winged, samaroid nut); 1 seeded. Seeds non-endospermic. Embryo well differentiated. Cotyledons 2 (thick, oily). Embryo straight.

Physiology, phytochemistry. Aluminium accumulation not found.

Geography, cytology. Paleotropical. Sub-tropical to tropical. Southern China, Indochina.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Juglandales (?). Cronquist’s Subclass Hamamelidae; Juglandales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Fagales (as a synonym of Juglandaceae).

Species 1. Genera 1; only genus, Rhoiptelea.

General remarks. The data compiled here show this species differing from Juglandaceae in numerous conspicuous features of vegetative, inflorescence and floral morphology, as well as in pollen morphology and the bitegmic, non-orthotropous ovules.

Illustrations. • Technical details: Rhoiptelea (Hutchinson).

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.’.