The families of flowering plants
Habit and leaf form. Small trees, or shrubs. Switch-plants; with the principal photosynthesizing function transferred to stems (and the green, striate branches ending in spines). Leaves much reduced (represented by minute, deltoid scales, above each of which is a conspicuous, black, triangular gland field). Xerophytic. Leaves minute; alternate; membranous.
Axial (stem, wood) anatomy. Internal phloem absent. Secondary thickening developing from a conventional cambial ring.
The parenchyma apotracheal. Included phloem absent.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in cymes. The ultimate inflorescence units cymose. Inflorescences lateral; short, 37 flowered cymes. Flowers minutely bracteate; regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent.
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5 (small, minutely glandular-fringed); 1 whorled; gamosepalous (connate basally); regular; persistent; imbricate. Corolla 5; 1 whorled; polypetalous; imbricate; regular; thickish, carinate within; deciduous.
Androecium 5. Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments subulate, persistent). Anthers apically introrse.
Gynoecium 5 carpelled. Carpels isomerous with the perianth. The pistil 5 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 5 locular. Gynoecium stylate. Styles 1; apical (thick, persistent). Stigmas 1; 5 lobed. Placentation axile. Ovules (3–)6 per locule; horizontal; biseriate; amphitropous.
Fruit non-fleshy (woody); dehiscent; a capsule. Capsules septicidal and loculicidal (partially loculicidal from the top). Seeds endospermic (the endosperm thin, fleshy); ascending, 12 per loculus; winged (the wing basal, membranous). Embryo straight.
Geography, cytology. Holarctic. Temperate to sub-tropical. Southwest U.S.A.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Santaliflorae (?); Celastrales (?). Cronquists Subclass Rosidae; Celastrales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Celastrales (as a synonm of Celastraceae).
Species 2. Genera 2; Acanthothamnus, Canotia.
General remarks. Differing somewhat unconvincingly from Celastraceae sensu stricto (q.v.) only in the single stigma and the horizontal, amphitropous ovules.
Illustrations. • Canotia holacantha: Nat. Pflanzenfam. II (1897).
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: 13th March 2017. delta-intkey.com/angio’.