The families of flowering plants
~ Euphorbiaceae, Picrodendraceae
Habit and leaf form. Trees (poplar-like in habit, with decussate branching); leptocaul. Leaves opposite; petiolate; simple, or compound; when simple, somewhat peltate; when compound, ternate, or palmate (37 foliolate); stipulate. Stipules intrapetiolar; concrescent; ochreate (forming an oblong, flattened sheath enclosing the terminal bud).
Axial (stem, wood) anatomy. Secondary thickening developing from a conventional cambial ring (?).
Reproductive type, pollination. Plants dioecious. Female flowers without staminodes.
Inflorescence, floral, fruit and seed morphology. Flowers solitary (when female), or aggregated in inflorescences (amentiform, cernuous, in shortly pedunculate triads when male); when solitary/female, axillary; in catkins (when male); small; acyclic (male), or cyclic (female). The perianth acyclic and the androecium acyclic (spiralled, in male flowers). Free hypanthium absent. Hypogynous disk absent (in both male and female flowers).
Perianth sepaline; 2–3 (in lateral members of the male triads), or 5 (in the terminal male flower), or 5–6 (in female flowers). Calyx 2–3 (in lateral members of the male triads), or 5 (in the terminal male flower), or 5–6 (in female flowers); polysepalous; more or less imbricate.
Androecium in male flowers 20–100 (?many, spiralled on an elongated axis). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens 20–100 (?many); polystemonous; filantherous (the filaments very short). Anthers apiculate. Pollen grains aperturate; 4–12 aperturate; (oligo-) foraminate.
Gynoecium in female flower, 3(–5) carpelled. The pistil 3(–5) celled. Gynoecium syncarpous; synstylovarious; superior. Ovary 3(–5) locular. Gynoecium stylate. Styles 3(–5); apical. Stigmas 3(–5). Placentation apical. Ovules 2 per locule; pendulous; non-arillate; crassinucellate.
Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal and loculicidal. Seeds endospermic.
Geography, cytology. Tropical. Southeast tropical Africa, Madagascar.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Malviflorae (?); Euphorbiales (?). Cronquists Subclass Rosidae; Euphorbiales. APG 3 core angiosperms; core eudicot; Superorder Santalanae; Order Santalales (as a synonym of Euphorbiaceae).
Species 1 (A. johnsonii, with several segregates reduced to synonymy). Genera 1; only genus, Androstachys.
General remarks. Exhibiting very peculiar inflorescences and male floral morphology, but seemingly otherwise separable from Euphorbiaceae only via the impressive ochreate stipules. The source of Airy Shaws 1973 reference to anatomical evidence being against inclusion in Euphorbiaceae has not been located.
Illustrations. • Androstachys johnsonii: Leandri in Flore de Madagascar (1958).
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: 9th January 2018. delta-intkey.com/angio’.