SAXIFRAGACEAE

Saxifragaceae is a family of herbaceous perennial flowering plants within the core eudicot order Saxifragales. The taxonomy has been greatly revised and the scope of the family much reduced in the era of molecular phylogenetic analysis. The family is divided into ten clades, with about 640 known species in about 35 accepted genera. About half of these consist of a single species, but about 400 of the species are in the type genus Saxifraga. The family is predominantly distributed in the northern hemisphere, but also in the Andes in South America.

Herbaceous perennials (rarely annual or biennial), sometimes succulent or xerophytic, often with perennating rhizomes. Leaves usually basally aggregated in alternate rosettes, sometimes on inflorescence stems. They are usually simple, rarely pinnately or palmately compound. Their margins may be entire, deeply lobed, cleft, crenate or dentate and petiolate with stipules.

Inflorescences are bracteate racemes or cymes. Flowers are hermaphroditic (bisexual), rarely unisexual (androdioecious), actinomorphic (rarely zygomorphic). The perianth is placed on a hypanthium that may be free or may be partly fused with the ovary (which is then semi-inferior). Sepals usually 5 but may be 3–10 and fused with hypanthium, occasionally petaloid. Petals are clawed, sometimes cleft at the tip or finely dissected. Stamens 5–10, free and opposite petals, anthers usually basifixed and opening by lengthwise slits. Ovary inferior to semi-inferior with two (sometimes three) carpels usually fused at the base, sometimes free, each topped with stylodium and capitate stigma. Ovules few to many, placentation axile or parietal, styles 2–3. Fruit usually septicidal capsule or follicle, with numerous small seeds.

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