[For Emanuel Sweert, ca. 1552–1612, Dutch gardener and illustrator]

James S. Pringle

Herbs perennial [monocarpic], chlorophyllous, glabrous [stems and leaves puberulent]. Leaves basal and cauline, opposite or all or distal leaves subopposite or alternate. Inflorescences thyrses or verticillasters, occasionally racemoid [flowers solitary or few]. Flowers 4- or 5-merous; calyx lobed nearly to base, lobes lanceolate; corolla violet-blue or pale green to white, usually with violet-blue markings and/or suffusions [rarely brownish red], rotate or nearly so, lobes much longer than tube, entire, plicae between lobes absent; stamens inserted near base of corolla tube, usually connected by corona consisting of low ridge from which trichomes [scales] arise between filaments; anthers distinct; ovary sessile [short-stipitate]; style persistent, erect, short [absent]; stigmas 2; nectaries in [1] 2 foveae per corolla lobe, rim of openings raised [rarely scarcely so], fringed. Capsules compressed-cylindric to ovoid. x = [7, 8, 9, 10, 12, 13] 14.

Species ca. 120 as commonly circumscribed (1 in the flora): North America, Eurasia, Africa, Pacific Islands (New Zealand); temperate to high-altitude tropical regions.

There are differences of opinion about the appropriate circumscription of Swertia. Some, for example, V. V. Zuev (1990) and J. Shah (1984), included all of the taxa treated here as Swertia and Frasera, along with many Asian and African species, within a broad concept of Swertia. Others, provisionally followed in this flora, segregate all of the species endemic to North America, including Mexico, as Frasera, but retain many Asian species similar in morphology in Swertia. Still others, for example, H. Toyokuni (1963), emphasizing chromosome numbers, advocated the restriction of Swertia to S. perennis, broadly circumscribed, this being the only species in the complex known to have n = 14 or any multiple of 7. This topic is further discussed under 11. Frasera.

SELECTED REFERENCES St. John, H. 1941. Revision of the genus Swertia (Gentianaceae) and the reduction of Frasera. Amer. Midl. Naturalist 26: 1–29. Shah, J. 1984. Taxonomic Studies in the Genus Swertia (Gentianaceae). Ph.D. thesis. University of Aberdeen.

Lower Taxon

• Swertia perennis Linnaeus