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..
[Solea Spreng. in Schrad. Journ. Bot. 4: 192. 1800.] [Ionidium Vent. Hort. Malm. pl. 27. 1803.] Herbs, rarely shrubs, with mostly opposite leaves, and axillary or racemose flowers. Sepals somewhat unequal, not prolonged posteriorly. Petals unequal, the lower one longest, gibbous or saccate at the base, the two upper shorter than the lateral ones. Filaments distinct, the lower spurred or glandular; anthers connivent, not united. Capsule elastically 3-valved. Seeds ovoid-globose, with hard seed-coats. [Latin, slipper-like.]
A genus of about 60 species, mainly natives of tropical America, a few in Asia and Australia. Type species: Viola Calceolaria L.
Viola verticillata Ort. Dec. Pl. 4: 50. 1797. Ionidium polygalaefolium Vent. Jard. Malm. pl. 27. 1803. Ionidium lineare Torr. Ann. Lye. N. Y. 2: 168. 1827. Calceolaria verticillata Kuntze, Rev. Gen. Pl. 41. 1891.
Somewhat pubescent or nearly glabrous, tufted from a woody base; stems erect or ascending, 4'-15' high, simple or branched. Leaves alernate, or the lower sometimes opposite, linear, oblong or oblanceolate, entire, obtuse, 9"-20" long, 1"-4" wide, often with smaller ones fascicled in their axils, and thus appearing verticillate; stipules subulate or foliaceous; flowers white, axillary, solitary, nodding, 2"-3' long; pedicels slender or filiform, 3"-7" long; capsule obovoid, 2" long; seeds nearly 1" long.
In dry soil, Kansas to Texas, Mexico, Colorado and New Mexico. April-July.