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The families of flowering plants

L. Watson and M.J. Dallwitz

Austrobaileyaceae (Croiz.) Croiz.

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

Leaf anatomy. Stomata on both surfaces (but more abaxially); anomocytic. The mesophyll with spherical etherial oil cells, or without etherial oil cells (?).

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Nodes unilacunar (with two traces). Primary vascular tissues in a cylinder, without separate bundles; collateral. Secondary thickening developing from a conventional cambial ring.

The wood diffuse porous. The vessels large; solitary. The vessel end-walls scalariform. The vessels with spiral thickening. The axial xylem with tracheids; with fibre tracheids (i.e. in addition to tracheids); without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal (terminal only).

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, phytochemistry. Not cyanogenic. Alkaloids absent. Iridoids doubtfully present. Saponins/sapogenins absent. Proanthocyanidins present. Sieve-tube plastids S-type.

Geography, cytology. Tropical. Queensland.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Laurales. Cronquist’s Subclass Magnoliidae; Magnoliales. APG III peripheral angiosperms; Superorder Austrobaileyanae. APG IV Order Austrobaileyales.

Species 1 (Austrobaileya scandens). Genera 1; only genus, Austrobaileya.

Illustrations. • Austrobaileya scandens, as A. maculata (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: 5th March 2018.’.