The families of flowering plants
Habit and leaf form. Microphyllous shrubs (with long- and short-shoots). 0.3–1.2 m high. Leptocaul. Xerophytic. Leaves small (721 mm long); alternate; spiral (on the long-shoots, clustered on the short-shoots); flat; leathery to fleshy (subcoriaceous, rather thick, fleshy); shortly petiolate to subsessile; non-sheathing; simple; epulvinate. Lamina entire; lanceolate, or oblong, or ovate (ovate to broadly oblong-lanceolate); (when cleared) pinnately veined to palmately veined; rounded at the base (and abruptly contracted into the peglike petiole). Leaves exstipulate. Lamina margins entire; flat.
Leaf anatomy. The leaf lamina dorsiventral to bifacial (with adaxial and abaxial palisades). Stomata on both surfaces; anomocytic. Hairs present (the leaves canescent-strigose pubescent, the hairs T-shaped, Malpighian type); eglandular; unicellular (though embedded in multicellular bases). Complex hairs absent.
Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow (all uniseriate). The axial xylem with vessels (these mostly solitary).
The wood semi-ring porous to diffuse porous. The vessel end-walls simple. The vessels without vestured pits. The axial xylem with fibre tracheids; with libriform fibres. The parenchyma apotracheal and paratracheal (mainly paratracheal); wood not storied.
Reproductive type, pollination. Plants hermaphrodite. Floral nectaries absent (?).
Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary (near the ends of the branchlets, on 3–5 mm pedicels); ebracteate?; ebracteolate? neither bracts nor bracteoles mentioned by Iltis et al; medium-sized to large (4–5 cm in diameter, showy); calyptrate (via the calyx); regular; 5–7 merous. Floral receptacle developing an androphore and developing a gynophore (the androphore short, the gynophore well developed). Free hypanthium absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla; 10, or 12, or 14; 2 whorled; isomerous. Calyx 5, or 6, or 7; 1 whorled; gamosepalous (calyptrate); entire; regular; persistent to not persistent; non-accrescent; calyptrate (ultimately splitting basipetally into one or two reflexed, semi-persistent flaps); valvate (or thus interpretable). Corolla 5, or 6, or 7; 1 whorled; polypetalous; imbricate; regular; bright blue (to lilac or violet); deciduous; non-accrescent. Petals clawed (ovate-spathulate); entire.
Androecium (40–)60–76. Androecial members unbranched (in obscure fascicles); maturing centrifugally; free of the perianth; markedly unequal; obscurely coherent, or free of one another (ostensibly only); 5 adelphous, or 6 adelphous, or 7 adelphous (the stamens ostensibly randomly arranged, but on close examination resolvable into 5, 6 or 7 fascicles, each comprising a radially-arranged row of pairs of stamens). The androecial bundles alternating with the corolla members. Androecium exclusively of fertile stamens. Stamens (40–)60–76; polystemonous; filantherous. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse; bilocular; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colpate.
Gynoecium 3 carpelled. Carpels reduced in number relative to the perianth. The pistil 3 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 3 locular; stipitate. Gynoecium stylate. Styles 1, or 3 (the style trifurcating above); if considered three, partially joined; attenuate from the ovary; apical. Stigmas 3. Placentation axile. Ovules 10–14 per locule; funicled; biseriate; anatropous; bitegmic.
Fruit non-fleshy; dehiscent; deeply trisulcate, a capsule, or a siliqua (i.e., on a short gynophore, with three valves dehiscing from a thin placental column, cf. two cruciferous valves separating from a replum?). Capsules valvular. Dispersal unit the seed. Fruit 6–30 seeded. Seeds non-endospermic (the endosperm one-layered, obsolete); small to medium sized (7–11 mm long); winged (at the cotyledonar end, and straight, by contrast with the reniform seeds otherwise characteristic of the order). Cotyledons 2. Embryo straight (large, flat, spathulate).
Seedling. Germination phanerocotylar.
Physiology, phytochemistry. Mustard-oils present.
Geography, cytology. Neotropical. Mexico.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Violiflorae; Capparales. Cronquists Subclass Dilleniidae; Capparales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Brassicales.
Species 1. Genera 1; the monotypic genus, Setchellanthus.
General remarks. Long uncomfortably referred to Capparidaceae; promoted to family rank on seemingly good morphological grounds, and with the support of data from nucleic acid sequencing, by Iltis et al. (1999).
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: 12th September 2017. delta-intkey.com/angio’.