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 glabrous and glaucous erect dichotomously branching herbs, with sessile clasping ovate or lanceolate acute leaves, and rather small red or pink slender-pedicelled flowers in terminal cymes. Calyx cylindric in flower, becoming sharply 5-angled and inflated in fruit, 5-toothed, not bracted at the base. Petals much longer than the calyx, not appendaged. Stamens 10. Styles 2. Capsule 4-toothed. Seeds laterally attached; embryo curved. [Latin, cow, in allusion to its value for fodder.]
About 3 species, natives of Europe and Asia, the following typical.
Saponaria Vaccaria L. Sp. Pl. 409. 1753. Vaccaria vulgaris Host, Fl. Aust. 1: 518. 1827. Vaccaria Vaccaria Britton, in Britt. & Br. 1ll. Fl. 2: 1897.
Branching above, 1°-3° high. Leaves lanceolate or ovate-lanceolate, l' - 3' long, 1/2'-1' wide, acute, connate at the base; flowers pale red, 3"-4" broad, borne in loose corymbose cymes; calyx oblong or ovate, 5"-7" long, 5-ribbed, much inflated and wing-angled in fruit; petals crenulate, with no scale at the base of the blade.
In waste places, Ontario to British Columbia, Florida, Louisiana and California. Locally abundant. Naturalized or adventive from Europe. Cow-basil. June-Aug.