Habit and leaf form. Glandular herbs. Perennial (occasionally stemless); rhizomatous, or tuberous. Leaves simple, or compound; when compound, pinnate. Lamina when simple, dissected; when dissected, pinnatifid; pinnately veined; cross-venulate. Leaves stipulate.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in panicles; regular; 5 merous; cyclic.
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous; regular; imbricate. Corolla 5; 1 whorled; polypetalous; contorted; deciduous. Petals clawed, or sessile.
Androecium 10, or 15 (if the five glands alternating with the petals are interpreted as staminodes). Androecial members free of the perianth; coherent; 1 adelphous (the filaments very shortly connate basally); 2 whorled, or 3 whorled (?). Androecium including staminodes. Staminodes 5; external to the fertile stamens; non-petaloid (represented by a whorl of glands, alternating with the petals). Stamens 10; diplostemonous; alternisepalous; both alternating with and opposite the corolla members. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse. Pollen grains aperturate; 2 aperturate; colporate.
Gynoecium 5 carpelled. Carpels isomerous with the perianth. The pistil 5 celled. Gynoecium syncarpous; synovarious; superior. Ovary 5 locular (deeply lobed). Gynoecium stylate. Styles 5; ‘styles arising from the base of the lobes and connate into a capitate stigma’. Placentation apical. Ovules 1 per locule; pendulous; anatropous to campylotropous (‘anacampylotropus’, the seed not or scarcely becoming campylotropous); bitegmic; crassinucellate.
Fruit non-fleshy; a schizocarp (with no persistent central column). Mericarps 5; of indehiscent, one-seeded mericarps. Seeds non-endospermic. Embryo curved.
Geography, cytology. Temperate to sub-tropical. South-east Europe to central Asia. X=5.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Geraniales. Cronquist’s Subclass Rosidae; Geraniales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid II. APG 3 (2009) Order: Sapindales.
Species 5. Genera 1; only genus, Biebersteinia.
Bakker et al. (1998) infer from rbcL and atpB sequencing that Biebersteinia merits family recognition, and that its relationships lie with Sapindales rather than Geraniales. The above description is very inadequate, e.g. re. the androecium.