The families of flowering plants

L. Watson and M.J. Dallwitz

Apodanthaceae Van Tiegh.

~ 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, or absent (being represented only by 1-several series of floral bracts). Plants rootless; totally parasitic (permeating the host tissues, with only the flowers exserted). Parasitic on aerial parts of the host (Berlinianche and Pilostyles being stem parasites of legumes, and Apodanthes of a range of families including Salicaceae, Burseraceae and Meliaceae). Leaves if the scales are interpreted as such, membranous (scales).

Leaf anatomy. Stomata absent.

Axial (stem, wood) anatomy. Secondary thickening absent (the vascular system vestigial or absent). The axial xylem if present, without vessels.

Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Plants monoecious, or dioecious (depending on the generic identity of the host legume, in P. hamiltonii). Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; minute to small; malodorous, or odourless (?); regular; cyclic. Floral receptacle developing an androphore (in male flowers, the anthers borne in one to several rows beneath the expanded, fleshy apex of the central synandrial column), or developing a gynophore (in female flowers, which exhibit an annular stigma around the margin of the gynoecial column), or with neither androphore nor gynophore (? - depending on interpretation of the columns). Free hypanthium absent.

Perianth sepaline, or petaline, or of ‘tepals’ (depending on interpretation); 4, or 5(–10); free; 1 whorled (within the whorls of scales); petaloid (at least in Pilosanthes); white (or cream), or red (or red below and cream tipped); fleshy to non-fleshy (imbricate).

Androecium of male flowers 20–100 (numerous members). Androecial members free of the perianth; 1–4 whorled (to ‘several’ whorls). Androecium exclusively of fertile stamens. Stamens 15–100 (‘numerous’); polystemonous; with sessile anthers. Anthers dehiscing via pores; unilocular, or bilocular (?); tetrasporangiate. Pollen shed as single grains. Pollen grains nonaperturate.

Gynoecium in female flowers, 4–8 carpelled (?). The pistil 1 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous (hard to interpret, the stout, columnar style being expanded apically into a large, complex disk, with stigmatal projections); inferior. Ovary 1 locular. Styles 1; apical. Placentation parietal. Ovules in the single cavity 50–100 (‘very numerous’, and very minute); non-arillate; hemianatropous to anatropous; bitegmic (with rudimentary outer integuments); tenuinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; persistent. Synergids pear-shaped. Endosperm formation nuclear (in Pilostyles). Embryogeny caryophyllad, or solanad (?).

Fruit fleshy; indehiscent; a berry; many. Seeds endospermic; minute. Embryo rudimentary at the time of seed release.

Geography, cytology. Holarctic, Paleotropical, Neotropical, Cape, and Australian. Temperate to tropical. Tropical S. America (Apodanthes, 10 spp.) and tropical Africa (Berlinianche, 2 spp.), with Pilostyles in N. and S. America (18 spp), Iran (1 sp.), and SW Australia (2 spp.).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Santaliflorae; Santalales. Cronquist’s Subclass Rosidae; Rafflesiales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Cucurbitales (?).

Species about 35. Genera 3; Apodanthes, Berlinianche, Pilostyles.

General remarks. Closely relalated to Raffesiaceae sensu stricto (q.v.), but differing in parasitizing the aerial parts of hosts, the very small flowers, and the free androecium, as well as in geographical distribution.

Illustrations. • Technical details: Apodanthes. • Technical details: Pilostyles (Lindley). • Pilostyles berteroi, as Apodanthes: Hook. Ic. Pl. 7–8 (1844).

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.’.