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. Leaves without a persistent basal meristem.
Leaf anatomy. Stomata present; on both surfaces; paracytic.
Stem anatomy. Secondary thickening developing from a conventional cambial ring. Xylem with libriform fibres. Wood partially storied (VPI).
Reproductive type, pollination. 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 unit 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 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Fabales (as a synonym of Surianaceae).
Species 2. Genera 1; only genus, Stylobasium.
Note that 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.