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The families of flowering plants

L. Watson and M.J. Dallwitz

Byblidaceae Domin

~ Lentibulariaceae.

Excluding Roridulaceae.

Habit and leaf form. Sub- shrubs, or herbs. Plants carnivorous. Trapping mechanism passive. The traps consisting of the sticky-glandular, non-irritable (flypaper-like) leaves. Perennial. Leaves alternate; spiral; non-sheathing; simple; epulvinate. Lamina entire; distally linear. Leaves exstipulate. Vernation coiled inwards from the tip; circinnate.

Leaf anatomy. The leaf lamina triangular in transverse section, becoming cylindrical towards the apex. Stomata present; paracytic. Hairs present; glandular (stalked and sessile glands with umbrella-shaped heads on all parts of the plants, secreting abundant mucilage).

Axial (stem, wood) anatomy. Primary vascular tissues comprising a ring of bundles (comprising about 9 bundles); collateral (to centric). Secondary thickening absent.

The vessel end-walls simple. The axial xylem with tracheids.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; ebracteate; regular; 5 merous; cyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous (basally). Calyx lobes markedly longer than the tube. Calyx regular; persistent; imbricate. Corolla 5; 1 whorled; gamopetalous (the petals cuneate, shortly connate basally). Corolla lobes markedly longer than the tube. Corolla imbricate, or contorted; regular. Petals apically fringed, or entire (B. gigantea).

Androecium 5. Androecial members free of the perianth, or adnate (to the base of the corolla tube); all equal, or markedly unequal (sometimes declinate); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; inserted when epipetalous, near the base of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members; erect in bud, or inflexed in bud. Anthers connivent; basifixed; non-versatile; dehiscing via pores, or dehiscing via short slits (the openings confluent over the anther tip); tetrasporangiate. Pollen grains aperturate; 3 aperturate, or 3–4 aperturate, or 6 aperturate; colporate (tri-), or colpate (3–4), or rugate (4- or 6-).

Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 2 locular. Styles 1. Stigmas 1; capitate. Placentation axile. Ovules 10–50 per locule (? — ‘many’); anatropous; unitegmic (sic — ab initio, Lang 1901); tenuinucellate. Outer integument not contributing to the micropyle. Endothelium differentiated. Endosperm formation probably cellular. Endosperm haustoria present; chalazal and micropylar.

Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Dispersal unit the seed. Seeds endospermic. Cotyledons 2. Embryo straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Not cyanogenic. Iridoids detected (? — see Gibbs 1974). Proanthocyanidins absent. Aluminium accumulation not found.

Geography, cytology. Temperate to sub-tropical. Northern and South-western Australia, New Guinea.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Araliiflorae, or Corniflorae (?); Cornales (?). Cronquist’s Subclass Rosidae; Rosales. APG III core angiosperms; core eudicot; Superorder Asteranae; lamiid. APG IV Order Lamiales.

Species 3. Genera 1; only genus, Byblis.

General remarks. Dahlgren presented Byblis in the Araliiflorae, but the presence of iridoids suggests it was misplaced there. This plant exemplifies the long-standing difficulties in distributing certain Dicot families between Dahlgren’s Araliiflorae and Corniflorae, but in this case referral to the Tenuinucelli seems unambiguous.

Illustrations. • Byblis gigantea: Bot. Mag. 128 (1902). • Byblis gigantea (Hutchinson).

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: 15th April 2018.’.