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..
Herbs, mostly annual or biennial, with sessile or amplexicaul leaves, and small or middle sized, commonly numerous, pink, white or yellow flowers in cymes or spikes. Calyx tubular, 5-4-lobed or -divided, the lobes or segments narrow, keeled. Corolla salverform, 5-4- lobed, the tube long or short, the lobes spreading, contorted, convolute in the bud. Stamens 5 or 4, inserted on the corolla-tube; filaments short-filiform; anthers linear or oblong, becoming spirally twisted. Ovary 1-celled, the placentae sometimes intruded; style filiform; stigma 2-lobed. Capsule oblong-ovoid or fusiform, 2-valved. Seed-coat reticulated. [Latin, 100 gold pieces, with reference to its supposed medicinal value.)
About 25 species, natives of the Old World, western North and South America, and in the West Indies. Besides the following, about 8 others occur in the western and southwestern parts of the United States. Type species: Gentiana Centaurium L.
1. C. spicatum.
Flowers cymose or cymose-paniculate. Basal leaves tufted. No tuft of basal leaves.
Corolla-lobes 1 1/2"-2 1/2" long.
2. C. Centaurium.
Flowers short-pedicelled; naturalized species.
3. C. pulchellum.
Flowers slender-pedicelled; native western species. Leaves oblong to linear-oblong.
4. C. exaltatum.
Upper leaves mere subulate bracts.
5. C. texcnie.
Corolla-lobes 31/2" -5" long.
6. C. calycosum.
Gentiana spicata L. Sp. Pl. 230. 1753. Erythraea spicata Pers. Syn. 1: 283. 1805. Centaurium spicatum Fernald, Rhodora 10: 54. 1908.
Annual, glabrous, erect, strict, usually branched, 6'-18' high. Leaves oblong or lanceolate-oblong, sessile, obtusish at the apex, clasping at the base, 1/2'-1 1/2' long, 2"-7" wide; flowers pink, sessile, distant and spicate-racemose on the mostly simple and leafless branches, about 8" long; tube of the corolla somewhat longer than the subulate calyx-segments, 2-3 times as long as the linear-oblong lobes; capsule 4"-5" long.
Coast of Nantucket, and at Portsmouth, Va. Naturalized from Europe. May-Sept.
Gentiana Centaurium L. Sp. Pl. 229. 1753.
Erythraea Centaurium Pers. Syn. 1: 283. 1805.
Annual, glabrous, erect, usually branched, 6'-15' high. Leaves oblong, apex obtuse, the base narrowed; the lower forming a basal tuft, l'-2 1/2' long, s"-6" wide; stem leaves smaller, distant, rounded at the sessile or slightly clasping base; flowers numerous, 6"-8" long, nearly sessile, in compound terminal mostly dense bracteolate cymes; corolla-lobes obtuse, 2 1/2"-3" long, about as long as the calyx-segments and one-third to one-half as long as the corolla-tube; stigmas oval.
In waste places, Nova Scotia and Quebec to Massachusetts, Illinois and Michigan. Naturalized from Europe. Earth-gall. Sanctuary. June-Sept.