Hydrangeaceae Dumort.
Herbs or softly woody shrubs, rarely climbers. Lvs usually opposite, rarely alternate, simple; stipules 0. Fls in cymes, panicles or corymbs, regular, 4-5-merous, usually ⚥, sometimes sterile with enlarged petal-like sepals. Calyx 5-merous; tube ± adnate to ovary; sepals imbricate. Petals 4-5, free, contorted or valvate. Stamens twice as many as petals or numerous; anthers basi- or medifixed, 2-locular. Ovary 2-6-locular or incompletely so, 1/2 to fully inferior; styles as many as loculi, free or partly connate; ovules numerous on axile or intrusive parietal placentas, anatropous. Fr. a loculicidal capsule; seeds numerous, small, sometimes winged and reticulate.
c. 10 genera, 115 spp., N. temperate and tropical, extending to S. Chile.
Along with several other families, the Hydrangeaceae is sometimes united within the Saxifragaceae as subfamily Hydrangeoideae.
