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The families of flowering plants

L. Watson and M.J. Dallwitz

Drosophyllaceae Chrtek, Slaviková & Studnicka

Habit and leaf form. Shrubs, or herbs (somewhat woody). Plants carnivorous. Trapping mechanism active. The traps constituted by sticky leaf glands, associated with subsequent, slow enclosure of the prey by movement of the blade (with stalked and sessile glands secreting digestive ferment, cf. those of Drosera, but in this plant the stalked ones have no power of movement). Perennial; with a basal aggregation of leaves; rhizomatous. Mesophytic to xerophytic (growing in dry, alkaline soils). Leaves marcescent; small to medium-sized; crowded, alternate; spiral; non-sheathing; simple. Lamina entire; linear (linear-elongate, basally and apically attenuate). Leaf development not ‘graminaceous’. Vernation coiled inwards from the tip; outwardly circinnate (seemingly a unique condition, and contrasting with the inwardly circinate leaves of Drosera spp.).

Axial (stem, wood) anatomy. Secondary thickening absent.

Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in corymbs. The ultimate inflorescence units racemose. Inflorescences wide corymbs. Flowers medium-sized to large (to 4 cm in diameter); regular; 5 merous; cyclic; tetracyclic, or pentacyclic (? - depending whether there are two whorls of stamens). Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; shortly gamosepalous. Calyx lobes markedly longer than the tube (acute). Calyx regular; persistent; imbricate. Corolla 5; 1 whorled; polypetalous; regular; yellow.

Androecium 10–20. Androecial members free of the perianth; all equal; free of one another; 1 whorled, or 2 whorled (?). Androecium exclusively of fertile stamens. Stamens 10–20; isomerous with the perianth, or diplostemonous; filantherous (the filaments basally compressed). Anthers dehiscing via longitudinal slits; extrorse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with one middle layer; of the ‘monocot’ type. Pollen shed as single grains. Pollen grains aperturate; 3-celled.

Gynoecium 5 carpelled. Carpels isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious; superior. Ovary 1 locular. Gynoecium stylate. Styles 5; free; apical. Stigmas 5; large, capitate. Placentation basal. Ovules in the single cavity 10–100 (i.e., many); ascending; non-arillate; anatropous; bitegmic. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked (with filiform apparatus). Endosperm formation nuclear.

Fruit non-fleshy; dehiscent; a capsule. Capsules papery, valvular. Dispersal unit the seed. Fruit 10–50 seeded (i.e., many-seeded). Seeds copiously endospermic; quite large, obovate, compressed and angled. Embryo well differentiated (small). Cotyledons 2. Embryo straight (?).

Physiology, phytochemistry. C3. Inulin recorded (Gibbs 1974).

Geography, cytology. Holarctic. Sub-tropical. Spain, Portugal and Morocco.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Theiflorae; Droserales. Cronquist’s Subclass Dilleniidae; Nepenthales. APG III core angiosperms; core eudicot; Superorder Caryophyllanae. APG IV Order Caryophyllales.

Species 1. Genera 1; Drosophyllum (D. lustitanicum).

General remarks. This curious, ostensibly Drosera-like carnivorous monotypic is now regarded as a caryophylloid relative of Ancistrocladaceae and Dioncophyllaceae.

Illustrations. • Drosophyllum lusitanicum: Bot. Mag. 95 (1869). • Glandular tentacle of Drosophyllum lusitanicum, with glandular hairs and enations of Drosophyllaceae (Aldrovanda, Dionaea, Drosera): (Solereder, 1908).

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: 5th March 2018.’.