The families of flowering plants
~ Rafflesiaceae sensu lato.
Habit and leaf form. Very peculiar endoparasitic herbs. Plants of very peculiar vegetative form; the vegetative parts filamentous, or fungoid. Leaves much reduced (at the bases of flowering stems, or beneath the flower), or absent (depending on interpretation). Plants rootless; totally parasitic (permeating the host tissues, with only the flowering stems exserted). Parasitic on roots of the host. Leaves (if the scales beneath the flowers are so interpreted,) alternate, or opposite, or whorled (usually); membranous (scales).
Leaf anatomy. Stomata absent.
Axial (stem, wood) anatomy. Secondary thickening absent (the vascular system vestigial or absent). The axial xylem when present, without vessels.
Reproductive type, pollination. Plants monoecious, or dioecious (?). Pollination entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences. Inflorescences spicate. Flowers small to medium-sized; malodorous (often), or odourless; regular; cyclic. Floral receptacle developing an androphore, or developing a gynophore, or with neither androphore nor gynophore (depending on interpretation of the floral columns).
Perianth sepaline, or petaline, or of tepals (depending on interpretation); 4 (always?); joined (forming a tube), or free (?); 1 whorled (preceded by numerous scales); somewhat fleshy, or non-fleshy (?).
Androecium of male flowers 15–100 (to many). Androecial members free of the perianth; united with the gynoecium, or free of the gynoecium (depending on morphological interpretation of the central column); free of one another (the elongate, sessile anthers arranged in a ring around the swollen head of the central column); 1 whorled. Androecium exclusively of fertile stamens. Stamens 15–100 (to many); with sessile anthers. Anthers dehiscing via longitudinal slits; extrorse; unilocular, or bilocular (?); tetrasporangiate. Microsporogenesis simultaneous. Pollen shed as single grains. Pollen grains aperturate; 2–3(–4) aperturate; colpate, or porate.
Gynoecium (in female flowers) 4–8 carpelled (? - several). The pistil 4–8 celled (?). Gynoecium syncarpous; synstylovarious, or eu-syncarpous (the stout, columnar style clavate); inferior. Ovary 4–8 locular (by deep intrusion of the placentas). Gynoecium stylate. Styles 1; apical. Stigmas truncate. Placentation parietal (or with the very minute ovules covering the inner surfaces of the partitions). Ovules 25–100 per locule (very numerous, and very minute); non-arillate; orthotropous; bitegmic; tenuinucellate. Outer integument not contributing to the micropyle.
Fruit fleshy; indehiscent; a berry; many. Seeds non-endospermic; minute. Embryo rudimentary at the time of seed release.
Physiology, phytochemistry. Sieve-tube plastids when present, lacking both protein and starch.
Geography, cytology. Temperate (warm), sub-tropical to tropical. Mediterranean, Africa and Madagascar.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgrens Superorder Santaliflorae; Santalales (cf. Hydnoraceae). Cronquists Subclass Rosidae; Rafflesiales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Malvales.
Species about 10. Genera 2; Bdallophytum, Cytinus.
General remarks. Differing from Rafflesiaceae in six characters involving inflorescence, perianth, pollen, ovule and seed.
Illustrations. • Le Maout and Decaisne: Cytinus. • Le Maout and Decaisne: Cytinus, with Rafflesia (Rafflesiaceae). • Cytinus sanguineus, as C. dioicus: Hook. Ic. Pl. 4 (1841). • Cytinus hypocistis. • Bdallophytum andrieuxii: Eichler, Bot. Zeitung 30 (1872).
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: 9th January 2018. delta-intkey.com/angio’.