Habit and leaf form. Trees, or shrubs. Switch-plants; with the principal photosynthesizing function transferred to stems (almost leafless, with stiff, spine-tipped branches). Leaves much reduced. Xerophytic. Leaves early deciduous; minute; alternate; membranous (scalelike); simple; exstipulate.
Stem anatomy. Secretory cavities present (in the phloem); with resin. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with tracheids; with fibre tracheids; without libriform fibres. Vessel end-walls simple. Wood ring porous; parenchyma apotracheal.
Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence unit racemose. Inflorescences axillary; very short axillary racemes. Flowers bracteate (the bracts minute); regular; 4 merous; cyclic. Floral receptacle developing a gynophore (the ovary shortly stipitate). Free hypanthium absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla; 8. Calyx 4; 2 whorled (K 2+2 decussate, C 4 diagonal, cf. Cruciferae?); polysepalous (the sepals small); regular; imbricate. Corolla 4; 1 whorled; polypetalous; imbricate; regular; white; deciduous. Petals clawed.
Androecium 8. Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens 8; diplostemonous; filantherous. Anthers dehiscing via longitudinal slits; introrse; apiculate. Pollen grains aperturate; (2–)3(–4) aperturate; colporate.
Gynoecium 2–5 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 2 locular. Gynoecium stylate. Styles 1 (subulate, persistent); apical. Placentation axile. Ovules 5–50 per locule (several to many); anatropous.
Fruit fleshy; indehiscent; a berry. Seeds scantily endospermic. Embryo well differentiated. Cotyledons 2. Embryo much curved.
Physiology, biochemistry. Mustard-oils present, or absent (?).
Geography, cytology. Holarctic and Neotropical. Southern U.S.A., Mexico.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Sapindales. Cronquist’s Subclass Dilleniidae; Capparales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Brassicales.
Species 1. Genera 1; only genus, Koeberlinia.
Description inadequate, e.g. regarding floral morphology, mustard oils.