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..
Annual branched herbs, with subulate stipulate leaves, much fascicled in the axils, and terminal cymes of white flowers. Sepals and petals 5. Stamens 10 or 5. Styles 5, alternate with the sepals. Capsule 5-valved, the valves opposite the sepals. Seeds compressed, acute-margined or winged. [Latin (from spergo), to scatter.]
Two or three species, natives of the Old World. The following typical species is widely distributed as a weed.
Spergula arvensis L. Sp. Pl. 440. 1753.
Slender, glabrous or sparingly pubescent, branching at or near the base, erect or ascending, 6'-18' high. Leaves narrowly linear or subulate, 1'-2' long, clustered at the nodes in two opposite sets of 6-8 together, appearing verticillate; stipules small, connate; flowers 2"-3" broad, numerous in loose terminal cymes; pedicels slender, divaricate; sepals ovate, 1 1/2"-2" 'long, slightly longer than the petals; stamens 10 or 5 in flowers on the same plant; capsule ovoid, longer than the calyx; seeds papillose.
In fields and waste places, frequent as a weed throughout eastern Canada and the Eastern and Middle States, south to South Carolina, west to California. Adventive or naturalized from Europe. Sandweed. Pick-purse. Yarr. Cow-quake. Summer.
Spergula sativa Boenn, which differs in being viscid, and with dotted but not papillose seeds, has been collected in New England and in Ontario. Native of Europe.