This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", 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..
Erect or diffuse branching, mostly silky-pubescent or pilose, annual or perennial herbs, with small usually entire leaves, and axillary solitary, racemose or paniculate, small blue pink or white flowers. Sepals nearly equal, acute or obtuse. Corolla funnelform, campanu-late or rotate, the limb plaited, 5-angled or 5-lobed. Stamens included or exserted; filaments filiform; anthers ovate or oblong. Ovary entire, 2-celled; style 2-divided to the base, or near it, each division deeply 2-cleft; stigmas linear-filiform. Capsule 2-celled, globose to ovoid, 2-4-valved, 1-4-seeded. Seeds glabrous. [Latin, unrolling.].
About 85 species, natives of warm and tropical regions. Besides the following, some 7 others occur in the southern United States. Type species: Evolvulus nummuldrius L.
Evolvulus argenteus Pursh, Fl. Am. Sept. 187. 1814. Not R. Br. 1810.
Evolvulus pilosus Nutt. Gen. 1: 174. 1818.
Perennial, densely silky-pubescent or villous; stems ascending or erect, 3'-9' high, very leafy. Leaves sessile, oblong, lanceolate or spatulate, 3"-9" long, 1 "-3" wide, acute or obtuse at the apex, narrowed at the base; flowers solitary and nearly sessile in the axils; peduncles 2-bracted at the base, recurved in fruit, 1"-2" long; sepals lanceolate, acute or acuminate; corolla funnelform-campanu-late, purple or blue, 3"- 6" broad; capsule 1 1/2"-2" in diameter, about as long as the sepals.
On dry plains, North Dakota to Missouri, Nebraska, Mexico and Arizona. May-July.