This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Low herbs, our species perennial, with oblong ovate ovate-lanceolate or linear soft leaves, sessile or very short-petioled, and small white flowers solitary in the axils or in terminal cymes. Sepals and petals 4 or 5. Stamens 8 or 10. Capsule oblong or ellipsoid, few-seeded. Seeds mostly smooth and shining, appendaged at the hilum by a membranous broad strophiole. [In honor of P. H. G. Moehring, naturalist of Danzig.]
About 20 species, natives of the northern hemisphere. Only the following are known to occur in North America. Type species: Moehringia muscosa L.
Leaves oblong or oval, usually obtuse; sepals obtuse or acute, shorter than the petals.
Leaves lanceolate, usually acute; sepals acuminate, longer than the petals.
Arenaria lateriflora L. Sp. Pl. 423. 1753.
Moehringia lateriflora Fenzl, Verbr. Alsin. table, p. 18. 1833.
Stems erect or ascending, simple or at length sparingly branched, finely pubescent throughout, 4'-12' high. Leaves thin, oval or oblong, 1/2'-1' long, obtuse, spreading, the margins and nerves ciliate; cymes lateral and terminal, few-flowered or flowers sometimes solitary; flowers 3"-4" broad, their parts in 4's or 5's; sepals oblong, obtuse or acute, half as long as the nearly entire petals; ovary at first 3-celled; capsule ovoid, nearly twice as long as the calyx, dehiscent by 3 2-cleft valves.
In moist places and on shores, southern New York and New Jersey to Missouri, north to Newfoundland and Alaska, extending south in the Rocky Mountains to New Mexico. Also in Oregon and British Columbia and in northern Europe and Asia. Showy-sandwort. May-July.
Arenaria macrophylla Hook. Fl. Bor. Am. 1: 102. pl. 37. 1830.
Moehringia macrophylla Torr. Bot. Wilkes' Exp. 246. 1874.
Stems decumbent, puberulent, usually branched, 6'-15' long. Leaves lanceolate, acute or acuminate (rarely obtusish) at the apex, narrowed at the base, 1-3' long, 2"-5" wide; cymes terminal or becoming axillary by the elongation of the stem, 1-5-flowered; flowers about 3" broad; sepals lanceolate or ovate-lanceolate, long-acuminate, longer than the small petals; capsule rather shorter than the calyx, 3-valved, the valves 2-cleft.
On shores and banks, Labrador to Connecticut, Lake Superior, Idaho and British Columbia, south to California. May-Aug.