9. Minuartia L. (sandwort)

Plants annual or perennial. Stems erect or ascending, sometimes with ascending branches from a spreading, somewhat matted branch system, usually branched, glabrous or sparsely to moderately pubescent with short, stalked glands. Leaves opposite, fused below into a usually cuplike sheath, sessile, with axillary clusters of leaves sometimes present. Stipules absent. Leaf blades narrowly linear to narrowly lanceolate and stiff or linear to oblanceolate and soft, not fleshy, tapered at the base, angled or tapered to a bluntly or sharply pointed tip, this sometimes with a short, fine, spinelike appendage, the surfaces glabrous. Flowers in terminal, open or dense panicles, the stalks erect to arched or spreading, the bracts paired and resembling small leaves, herbaceous or with thin, white to translucent margins. Epicalyx absent. Sepals 5, fused at the base, ovate to broadly lanceolate, green or sometimes purplish-tinged at the tip, narrowly angled or tapered to a sharply pointed tip, not appearing hooded or awned, the margins thin and white. Petals 5, obovate to oblong-obovate, tapered but not to a stalklike base, rounded to more or less truncate or notched at the tip, white, lacking appendages. Stamens 10, the filaments distinct, attached to the calyx tube. Staminodes absent. Pistil with 1 locule, sessile. Styles 3, distinct, each with a stigmatic area along the inner surface. Fruits capsules, dehiscing apically by 3 incurved to recurved valves or teeth. Seeds 1–25, nearly globose, the surface tuberculate or with papillae, sometimes appearing pebbled, brown or black, lacking wings or appendages. About 175 species, North America, Europe, Asia.

Steyermark (1963) and many earlier North American authors included the species of Minuartia in a broadly circumscribed concept of Arenaria. McNeill (1962, 1980) presented compelling morphological evidence to support the recognition of two genera and published many of the new combinations necessary to transfer species into Minuartia.