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The families of flowering plants

L. Watson and M.J. Dallwitz

Simmondsiaceae (Pax) Van Tiegh.

Habit and leaf form. Rigid, divaricately branching shrubs. Xerophytic. Leaves persistent; small (about 2 cm long); opposite (and decussate); flat; leathery; shortly petiolate; simple (but jointed at the base). Lamina entire; oblong, or ovate; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire; flat.

Leaf anatomy. The leaf lamina bifacial (with mesophyll entirely composed of palisade cells). Stomata on both surfaces (and equally numerous); somewhat depressed, anomocytic. Hairs present; eglandular, or eglandular and glandular (?); multicellular. Multicellular hairs quite long, uniseriate; simple (with one or two relatively thin walled terminal cells which may be glandular). Complex hairs absent. The mesophyll containing crystals. The crystals druses and solitary-prismatic.

Axial (stem, wood) anatomy. Cork cambium present; initially deep-seated (in the pericycle). Primary vascular tissues collateral. Internal phloem absent. Secondary thickening anomalous. The anomalous secondary thickening via concentric cambia (resulting in successive rings of xylem and phloem, separated from one another by narrow circles of lignified paranchyma).

The vessel end-walls simple. The vessels with spiral thickening. The axial xylem with tracheids; with fibre tracheids. The parenchyma apotracheal (very rare, except for conjunctive tissue associated with the anomalous structure). ‘Included’ phloem present.

Reproductive type, pollination. Plants dioecious.

Inflorescence, floral, fruit and seed morphology. Flowers solitary (female, sometimes), or aggregated in ‘inflorescences’; when aggregated, in racemes (female), or in heads (male). Inflorescences and solitary female flowers axillary; in pedunculate, cernuous capitate clusters (male), or in pendulous 2–7 flowered racemes or the flowers solitary (female). Flowers small; regular; (4–)5(–6) merous; cyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth sepaline; (4–)5(–6); 1 whorled. Calyx (4–)5(–6); 1 whorled; polysepalous; regular; of female flowers, persistent; accrescent (foliaceous); imbricate (fringed).

Androecium (8–)10(–12). Androecial members free of the perianth; all equal; free of one another (more or less distant on the flat receptacle). Androecium exclusively of fertile stamens. Stamens (8–)10(–12); diplostemonous; filantherous (the filaments short and stout). Anthers basifixed (or ventrifixed); dehiscing via longitudinal slits; conspicuously extrorse (the outer more so than the inner); tetrasporangiate. Microsporogenesis simultaneous. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colpate to porate (the apertures poorly defined); 2-celled.

Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil 3 celled. Gynoecium syncarpous; synovarious; superior. Ovary 3 locular. Gynoecium stylate. Styles 3; free; apical. Stigmas papillate. Placentation axile to apical. Ovules 1 per locule; pendulous; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Endosperm formation nuclear.

Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Fruit 1 seeded (two of the locules empty). Seeds non-endospermic; large; glandular and conspicuously hairy. Embryo well differentiated. Cotyledons 2 (fleshy, thickened, containing a cyanogenic glycoside and liquid wax instead of the more usual storage compounds). Embryo straight.

Physiology, phytochemistry. At least the seeds cyanogenic. Alkaloids absent. Iridoids not detected. Betalains absent. Proanthocyanidins present.

Geography, cytology. Holarctic and Neotropical. Warm temperate. California.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Euphorbiales. Cronquist’s Subclass Rosidae; Euphorbiales. APG III core angiosperms; core eudicot; Superorder Caryophyllanae. APG IV Order Caryophyllales.

Species 2 (Simmonsia cajifornica, S. chinensis). Genera 1; Simmondsia.

Illustrations. • Le Maout and Decaisne: Simmondsia chinensis. • Simmondsia californica: Nat. Pflanzenfam. III (1896).

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.’.