Ixerbaceae Griseb. ex Doweld & Reveal
~ Strasburgeriaceae (APG), formerly Brexiaceae, Escalloniaceae, etc.
Habit and leaf form. Small, glabrous trees (to about 15 m high); non-laticiferous and without coloured juice. Mesophytic (in hilly forests). Leaves evergreen; medium-sized (about 6–15 cm long); mostly sub- opposite, or whorled; flat; somewhat leathery; petiolate; not gland-dotted; simple. Lamina entire; linear to lanceolate (glabrous, acute or sub-acute); pinnately veined; attenuate at the base. Leaves exstipulate. Lamina margins obtusely serrate to dentate (the teeth gland-tipped). Leaves without a persistent basal meristem.
Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles. The ultimate inflorescence unit cymose. Inflorescences few-flowered, axillary. Flowers medium-sized; regular; 5 merous; tetracyclic. Free hypanthium present to absent. Hypogynous disk present; of separate members to annular (in the form of a 5-lobed disk alternating with the stamens).
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; shortly gamosepalous; 5- toothed. Calyx lobes markedly longer than the tube. Calyx regular; not persistent (the lobes deciduous); imbricate. Corolla 5; polypetalous (inserted beneath the obscurely 5-lobed perigynous disk); imbricate; regular; white. Petals obovate, shortly clawed; entire.
Androecium 5. Androecial members free of the perianth; all equal; free of one another; 1 whorled. Stamens 5; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments filiform). Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse.
Gynoecium 5 carpelled. Carpels isomerous with the perianth. The pistil 5 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 5 locular; sessile. Gynoecium stylate. Styles 1 (the style subulate, twisted and 5-furrowed); attenuate from the ovary; apical. Stigmas 1. Placentation axile. Ovules 2 per locule; funicled; horizontal; collateral; non-arillate; anatropous (?).
Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal (loculicidally 5 valved, the valves extending through the style, ultimately recurved, cohering below, bipartite above). Dispersal unit the seed. Fruit about 4–10 seeded. Seeds endospermic to non-endospermic (i.e., almost exalbuminous). Endosperm oily. Seeds quite large, oblong, compressed, shining. Embryo well differentiated (large). Cotyledons 2. Embryo straight.
Geography, cytology. Antarctic. Temperate. Endemic to New Zealand, North Island.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Saxifragales. Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Crossosomatales (as a synonym of Strasburgeriaceae).
Species 1. Genera 1; Ixerba (I. brexioides).
Economic uses, etc. A valued source of honey.
• Ixerba brexioides: Hook. Ic. Pl. 1843).
• Technical details: Ixerba (with Brexia).
Miscellaneous. This draft description by LW (2009) lacks information on embryology, anther development, pollen and phytochemistry.