Family Austrobaileyaceae

Austrobaileyaceae (Croiz.) Croiz.

Habit and leaf form. Lianas; bearing essential oils. Perennial. Climbing. Leaves evergreen; opposite (to sub-opposite); leathery; petiolate; simple. Lamina pinnately veined; cross-venulate. Leaves stipulate. Stipules intrapetiolar; caducous (small). Lamina margins entire.

Leaf anatomy. The mesophyll with spherical etherial oil cells, or without etherial oil cells (?).

Stem anatomy. Nodes unilacunar (with two traces). Secondary thickening developing from a conventional cambial ring. Xylem with tracheids; with fibre tracheids (i.e. in addition to tracheids). Vessel end-walls scalariform. Sieve-tube plastids S-type.

Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous; probably via diptera.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; bracteate; bracteolate; large; malodorous; regular; acyclic. The perianth acyclic, the androecium acyclic, and the gynoecium acyclic.

Perianth sequentially intergrading from sepals to petals; (9–)12(–14); free (imbricate).

Androecium 12–25. Androecial members maturing centripetally; free of the perianth; free of one another. Androecium including staminodes. Staminodes 6–12; internal to the fertile stamens (the inner members of the spiral reduced and sterile); petaloid. Stamens 6–20 (?); laminar, petaloid, and filantherous. Anthers adnate (the thecae adaxial); non-versatile; dehiscing via longitudinal slits; introrse (the thecae adaxial). Pollen grains aperturate; 1 aperturate; sulcate.

Gynoecium (6–)9(–12) carpelled; apocarpous (spiralled); eu-apocarpous; superior. Carpel 8–14 ovuled. Placentation marginal (biseriate). Ovules collateral; anatropous; bitegmic; crassinucellate.

Fruit ‘berry-like’; an aggregate (?—the descriptions seen not safely interpretable). The fruiting carpel indehiscent; baccate. Seeds endospermic. Endosperm ruminate.

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Not cyanogenic. Alkaloids absent. Iridoids doubtfully present. Proanthocyanidins present. Saponins/sapogenins absent.

Geography, cytology. Tropical. Queensland.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Laurales. Cronquist’s Subclass Magnoliidae; Magnoliales. APG (1998) oddment family. APG 3 (2009) Order: Austrobaileyales.

Species 2. Genera 1; only genus, Austrobaileya.

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