| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Stylobasiaceae J.G. Agardh

~ Rosaceae, Surianaceae, Chrysobalanaceae.

Habit and leaf form. Shrubs; leptocaul. Xerophytic. Leaves small to medium-sized; alternate; leathery; petiolate; non-sheathing; simple. Lamina entire; linear, or oblong, or oblanceolate; pinnately veined; cross-venulate. Leaves stipulate (then the stipules minute), or exstipulate. Lamina margins entire. Leaf development not ‘graminaceous’.

Leaf anatomy. Stomata present; on both surfaces; paracytic.

Axial (stem, wood) anatomy. Secondary thickening developing from a conventional cambial ring.

The axial xylem with libriform fibres. The wood partially storied (VPI).

Reproductive type, pollination. Unisexual flowers present, or absent. Plants hermaphrodite, or polygamomonoecious. Female flowers with staminodes (these long, filiform). Gynoecium of male flowers pistillodial. Pollination anemophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence units racemose. Inflorescences axillary; axillary leafy racemes. Flowers bracteolate; small to medium-sized; regular; tetracyclic. Floral receptacle not markedly hollowed. Free hypanthium absent. Hypogynous disk absent.

Perianth sepaline (the corolla absent); 5; 1 whorled. Calyx 5; 1 whorled; gamosepalous; campanulate; regular; persistent; imbricate; with the median member posterior.

Androecium 5. Androecial members free of the perianth; all equal; free of one another; 2 whorled. Androecium of male and hermaphrodite flowers exclusively of fertile stamens. Stamens 5; diplostemonous; filantherous (the filaments filiform). Anthers basifixed (long, exserted); dehiscing via longitudinal slits; extrorse.

Gynoecium 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel stylate; with a gynobasic style; 2 ovuled. Placentation basal. Ovules ascending; non-arillate; anatropous; crassinucellate.

Fruit non-fleshy. The fruiting carpel indehiscent; nucular, or drupaceous (surrounded by the enlarged calyx). Fruit 1 seeded. Seeds very sparsely endospermic.

Seedling. Germination phanerocotylar.

Geography, cytology. Temperate. Southwest Australia.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae, or Rosiflorae (cf. Fernando et al 1993); if Rosidae, Rosales (or near Polygalales); (if Rutiflorae) Rutales. Cronquist’s Subclass Rosidae; Rosales. APG III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Fabales (as a synonym of Surianaceae).

Species 2. Genera 1; only genus, Stylobasium.

General remarks. Satisfactory representation of recent notions on the proper dispositions of several genera previously referred to Simaroubaceae will necessitate thorough overhaul of the descriptions presented in this package (cf. Irvingiaceae, Kirkiaceae, Picramniaceae, Simaroubaceae, Surianaceae. Meanwhile, the present compilation of data has Stylobasiaceae differing conspicuously from Surianaceae (q.v.) in numerous characters (racemes, no corolla, equal stamens with basifixed, extrorse anthers, dry fruits, endospermic seeds), as well as in anatomical characters depending on limited sampling (paracytic stomata, partially storied wood).

Illustrations. • Stylobasium lineare, as Macrostigma australe: Hook. Ic. Pl. 5–6 (1842–3). • Stylobasium spathulatum, LS flower: Nat. Pflanzenfam. III (1894), with Chrysobalanaceae.

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: 8th June 2026. delta-intkey.com’.

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