The World Flora Online

Subshrubs, shrubs, trees, or vines [herbs], evergreen or deciduous. Leaves usually opposite, sometimes whorled [alternate], simple; stipules absent; petiole present or absent; blade sometimes palmately lobed, margins entire, serrate, serrulate, dentate, denticulate, or crenate; venation pinnate or acrodromous (Fendlera, Fendlerella, Philadelphus, Whipplea). Inflorescences terminal or axillary, cymes, panicles, racemes, or corymbs, or flowers solitary. Flowers bisexual [unisexual], or sometimes marginal ones sterile, radially symmetric (bisexual ones) or bilaterally symmetric with enlarged petaloid sepals (sterile ones); perianth and androecium nearly hypogynous, perigynous, or epigynous; hypanthium completely adnate to ovary or adnate to ovary proximally, free distally; sepals 4–12, distinct or connate basally; petals 4–12, connate basally [entirely, then calyptrate]; nectary usually present, rarely absent; stamens 8–200, usually distinct, sometimes connate proximally, free; anthers dehiscing by longitudinal slits; pistil 1, 2–12-carpellate, ovary less than 1/2 inferior, 1/2 inferior, or completely inferior, 1–12-locular, placentation usually axile proximally, parietal distally, rarely strictly axile or parietal; ovules 1–50 per locule, anatropous; styles 1–12, distinct or connate proximally to most of length; stigmas (1–)2–12. Fruits capsules [berries], dehiscence septicidal, loculicidal, interstylar, or intercostal. Seeds 1–50 per locule, funicular appendage present (Fendlerella, Whipplea) or absent.

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Fls borne in complex, basically cymose infls, perfect and regular (or the marginal ones often neutral and irregular, with enlarged, petaloid sep), mostly half to fully epigynous with an only shortly or scarcely prolonged hypanthium, but hypogynous or nearly so in some extralimital small genera; cal-lobes 4–5(–12); pet 4–5(–12), distinct; stamens mostly 8–many; filaments distinct or only slightly connate at base; carpels (2)3–5(–12), united to form a compound ovary, the styles in most genera distinct or shortly connate below, often stigmatic for much of their length; ovules mostly several or many on each of the axile or intruded parietal placentas; fr a capsule, or seldom a berry; seeds with a straight, linear, dicotyledonous embryo embedded in the endosperm; mostly shrubs or woody vines or small trees with opposite (rarely whorled), exstipulate, simple (sometimes lobed) lvs. 17/170.

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SELECTED REFERENCES De Smet, Y. et al. 2015. Molecular phylogenetics and new (infra)generic classification to alleviate polyphyly in tribe Hydrangeeae (Cornales: Hydrangeaceae). Taxon 64: 741–752. Hufford, L. 1995. Seed morphology of Hydrangeaceae and its phylogenetic implications. Int. J. Plant Sci. 156: 555–580. Hufford, L. 1997. A phylogenetic analysis of Hydrangeaceae based on morphological data. Int. J. Plant Sci. 158: 652–672. Hufford, L. 1998. Early development of androecia in polystemonous Hydrangeaceae. Amer. J. Bot. 85: 1057–1067. Hufford, L. 2004. Hydrangeaceae. In: K. Kubitzki et al., eds. 1990+. The Families and Genera of Vascular Plants. 10+ vols. Berlin etc. Vol. 6, pp. 202–215. Hufford, L., M. L. Moody, and D. E. Soltis. 2001. A phylogenetic analysis of Hydrangeaceae based on sequences of the plastid gene matK and their combination with rbcL and morphological data. Int. J. Plant Sci. 162: 835–846. Small, J. K. and P. A. Rydberg. 1905. Hydrangeaceae. In: N. L. Britton et al., eds. North American Flora.... 1905+. New York. 47+ vols. Vol. 22, pp. 159–178. Soltis, D. E., Xiang Q. Y., and L. Hufford. 1995. Relationships and evolution of Hydrangeaceae based on rbcL sequence data. Amer. J. Bot. 82: 504–514. Spongberg, S. A. 1972. The genera of Saxifragaceae in the southeastern United States. J. Arnold Arbor. 53: 409–498.

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