Family Byblidaceae

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. Leaves alternate; spiral; non-sheathing; simple; epulvinate. Lamina entire; linear. Leaves exstipulate. Vernation circinnate; circinnate.

Leaf anatomy. Stomata present; paracytic. Hairs present; glandular.

Stem anatomy. Secondary thickening absent. Xylem with tracheids. Vessel end-walls scalariform, or simple.

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, biochemistry. 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 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Lamiales.

Species 3. Genera 1; only genus, Byblis.

Dahlgren presented Byblis in the Araliiflorae, but the presence of iridoids suggests it is misplaced there. Byblis exemplifies the well known difficulties in distributing certain Dicot families between Dahlgren’s Araliiflorae and Corniflorae, but in this case referral to the Tenuinucelli seems unambiguous.