1. Comastoma tenellum (Rottbøll) Toyokuni, Bot. Mag. (Tokyo). 74: 198. 1961.
[F]
Samiland or Danes’ or slender or one-flowered gentian, spæd ensian, gentiane délicate
Gentiana tenella Rottbøll, Skr. Kiøbenhavnske Selsk. Laerd. Elsk. 10: 436, plate 2, fig. 6. 1770; G. tenella var. monantha (A. Nelson) J. Rousseau & Raymond; Gentianella tenella (Rottbøll) Börner; G. tenella subsp. pribilofii J. M. Gillett; Lomatogonium tenellum (Rottbøll) Á. Löve & D. Löve
Herbs 1–15(–26) cm. Stems decumbent to erect, solitary or clustered, simple or branched from base or throughout. Leaves: basal blades elliptic-oblong to spatulate, 3–20 × 1–5 mm; cauline blades elliptic to ovate or lanceolate, 4–9 × 1–3 mm. Inflorescences: solitary flowers at ends of main stem and branches (if any); peduncles 2–10 cm. Flowers: calyx 4–11 mm, base minutely saccate, 2 outer lobes ovate-triangular to lanceolate, inner lobes lanceolate, shorter; corolla pale violet-blue to white or greenish white, 6–17 mm, lobes spreading, ovate-oblong, 2–4.5 mm, apex obtuse, with 2 short scales deeply fringed. 2n = 10, also reported from Eurasia.
Flowering summer–early fall. Sea and lakeshores, tundra, dry to wet, rocky montane to alpine meadows; 0–3900 m; Greenland; N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo., restricted to high elevations southward; Eurasia.
A report of Comastoma tenellum from British Columbia was based on a collection reidentified as Gentianella amarella subsp. acuta in studies for this flora. Other reports from that province remain unsubstantiated.
Plants from the Pribilof Islands in the Bering Strait were distinguished as Gentianella tenella subsp. pribilofii on the basis of more branching, shorter internodes, and wider outer calyx lobes rounded to truncate at the base rather than cuneate or more narrowly rounded. However, in studies for this flora, similar specimens have been seen from interior Alaska, the Yukon Territory, Banks Island (Northwest Territories), and elsewhere. Some plants from the Rocky Mountains have more slender calyces than those of plants from the arctic coasts, with the sepals less strongly unequal, but many specimens from interior localities show no such tendencies or are intermediate in morphology. Other alleged differences between interior and coastal North American populations, or between North American and Eurasian populations, have not been substantiated in this study.