Araujia Brot.

Scientific Description

Common name. Mothplant. Family Asclepiadaceae.

Sometimes included in Apocynaceae. Subfamily Asclepiadoideae, Tribe Asclepiadeae.

Habit and leaf form. Lianas; laticiferous (with white latex). ‘Normal’ plants. Plants with roots (fibrous). Perennial. Leaves cauline. Young stems cylindrical. Climbing. Mesophytic. Leaves medium-sized; not fasciculate; opposite; not decurrent on the stems; ‘herbaceous’; not imbricate; petiolate. Petioles wingless. Leaves simple; epulvinate. Leaf blades dorsiventral (markedly discolorous); entire; flat; ovate; pinnately veined; cross-venulate; truncate. Leaf blade margins entire; flat.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes (in ‘fascicles’). Inflorescences simple; axillary; of 2–4 fascicles. Flowers pedicellate; medium-sized; regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; polysepalous (rarely), or gamosepalous; lobed; lobulate. Calyx lobes markedly longer than the tube. Calyx spreading; imbricate, or valvate; exceeded by the corolla; regular. Epicalyx absent. Corolla present; 5; 1 -whorled; appendiculate (with a corolline corona of 5 discrete lobes); gamopetalous; lobed; lobulate. Corolla lobes markedly longer than the tube. Corolla tubular (salverform); regular; cream to pink. Corolla lobes ovate (valvate). Androecium present. Androecial members definite in number. Androecium 5. Androecial members adnate (epipetalous); united with the gynoecium; all equal; coherent (connate); 1 -whorled. Stamens 5; all more or less similar in shape (not markedly capitate); isomerous with the perianth. Filaments appendiculate; connate into a tube, adnate to stigma. Anthers all alike; appendaged. The anther appendages apical. Pollen shed in aggregates; in tetrads. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; synstylous; superior. Ovary plurilocular; 2 locular. Gynoecium stylate. Styles partially joined (at the stylehead); apical. Stigmas 1; elongate-rostrate. Placentation axile. Ovules 30–50 per locule (‘many’); pendulous.

Fruit and seed features. Fruit 70–100 mm long; dehiscent; 1 locular (in 2 follicles, with one often aborting). Dispersal unit the seed. Seeds endospermic. Endosperm oily. Seeds compressed; conspicuously hairy (comose at micropylar end); with a tuft of hairs. Cotyledons 2.

Geography, cytology, number of species. World distribution: pantropical. Adventive. Australian states and territories: Western Australia, South Australia, Queensland, New South Wales, and Australian Capital Territory. 1 species naturalised in Australia. A genus of 3 species; A. sericifera Brot. Moth Vine; 0 endemic to Western Australia.

Additional comments. Named for A. de Araujo, a Prince of Portugal.

Additional characters Calyx with colleters (secreting mucilage) (at sinus bases). Annular corona absent. Corolline corona present; adnate to gynostegium (consisting of 5 discrete lobes adnate to base of staminal column and sides of corolla tube). Gynostegial corona absent. Corpusculum oblong, with flap of clear tissue at apex. Caudicles not winged; not geniculate. Pollinia in the anther locule pendulous; pellucid germinating mouth of pollinia absent. Pollen tetrads linear. Mature leaf blades bearing colleters (2 at lamina base).

Etymology. After A. de Araujo, a Prince of Portugal.