Family Simmondsiaceae

Simmondsiaceae (Pax) Van Tiegh.

Habit and leaf form. Rigid, divaricately branching shrubs. Xerophytic. Leaves evergreen; small (about 2 cm long); opposite; 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. Stomata on both surfaces (and equally numerous); anomocytic.

The mesophyll containing calcium oxalate crystals. The mesophyll crystals druses and solitary-prismatic.

Stem anatomy. Cork cambium present; initially deep-seated (in the pericycle). Internal phloem absent. Secondary thickening anomalous; via concentric cambia. ‘Included’ phloem present. Xylem with tracheids. Vessel end-walls simple. Wood parenchyma apotracheal (very rare, except for conjunctive tissue associated with the anomalous structure).

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; conspicuously hairy (and glandular). Embryo well differentiated. Cotyledons 2 (fleshy, thickened, containing a cyanogenic glycoside and liquid wax instead of the more usual storage compounds). Embryo straight.

Physiology, biochemistry. Not cyanogenic. Alkaloids absent. Iridoids not detected. Proanthocyanidins present.

Geography, cytology. Holarctic and Neotropical. Temperate (warm). California.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Euphorbiales. Cronquist’s Subclass Rosidae; Euphorbiales. APG 3 core angiosperms; core eudicot; Superorder Caryophyllanae; Order Caryophyllales.

Species 1. Genera 1; Simmondsia chinensis.

Illustrations.
• Technical details: Simmondsia.