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..
Perennial herbs, with alternate membranous leaves, and rather large blue or bluish flowers, in terminal thyrsoid or corymbose cymes. Calyx 5-parted, the segments narrow, acuminate. Corolla mostly salverform, the tube cylindric, but somewhat dilated at the summit, villous within. Stamens inserted on the throat of the corolla, included; anthers ovate or oblong. Disk none. Ovary of 2 carpels, connected at the top by the filiform style; ovules in 2 rows in each cavity, numerous; stigma appendaged by a reflexed membrane. Fruit of 2 cylindric several-seeded follicles. Seeds cylindric or oblong, obliquely truncate at each end, not appendaged. [Named for Charles Amson of South Carolina.]
About 8 species, natives of North America and eastern Asia. Besides the following, 5 others occur in the southern and southwestern United States. Type species: Amsonia Tabernaemontana Walt.
Tabernaemontana Amsonia L. Sp. Pl. Ed. 2, 308.
Glabrous or nearly so, simple, or branched above, 2°-4° high. Leaves ovate, ovate-lanceolate or lanceolate, entire, acuminate at the apex, narrowed at the base, sometimes pubescent beneath, 2'-4' long, i-2'wide; petioles 2"-4" long; flowers numerous; pedicels bracteolate at the base; calyx about 1" long, its segments subulate; corolla 6"- 9" long, beaked by the convolute limb in the bud, its lobes linear and about as long as the tube; follicles 2'-4' long, about 2" thick, attenuate at the apex, glabrous, divergent or ascending; seeds papillose.
In moist soil. New Jersey to Illinois, Kentucky, Missouri, Florida and Texas. Consists of several races, differing in leaf-form. April-July.
2. ViNCA L. Sp. Pl. 209. 1753. Erect or trailing herbs, some species slightly woody, with opposite leaves, and large solitary blue pink or white axillary flowers. Calyx 5-parted, the segments narrow, acuminate. Corolla salverform, the tube cylindric, or expanded above, pubescent within, the lobes convolute, at least in the bud, oblique. Stamens included. Disk of 2 glands, alternate with the 2 carpels. Ovules several in each carpel; style filiform; stigma annular, its apex penicillate. Follicles 2, erect or spreading, cylindric, several-seeded. Seeds oblong-cylindric, truncate at each end, not appendaged. [The Latin name.]
About 12 species, natives of the Old World. Type species: Vinca major L.
Vinca minor L. Sp. Pl. 209. 1753.
Perennial, trailing, glabrous; stems 6'-2° long. Leaves oblong to ovate, entire, firm, green both sides, obtuse or acutish at the apex, narrowed at the base, short-petioled, 1-21/2' long, 1/2-1' wide; flowers not numerous, solitary in some of the axils, blue,9"-15" broad; peduncles slender, 1/2'-1 1/2 long; calyx very deeply parted, the segments subulate-lanceolate, glabrous, about 1 1/2' long; corolla-tube expanded above, as long as or slightly longer than the obovate, nearly truncate lobes; anther-sacs with a broad connective; follicles few-seeded.