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Herbs biennial or annual, 0.1–1.5(–2.5) dm, glabrous. Stems generally 1, decumbent, from a tap root. Leaves basal and cauline, all ± similar; cauline leaves spreading, gradually more widely spaced distally; blade spatulate-obovate to widely oblanceolate or distal blades ovate, 0.2–1.2 cm × 1–4 mm, obscurely or not white-margined, apex mucronate. Inflorescences solitary flowers at ends of branches. Flowers usually 4-, occasionally 5-merous; calyx 3–15 mm, lobes triangular, 1–2.5 mm, margins not ciliate; corolla medium to deep blue or occasionally white, nearly salverform, open, 7–25 mm, lobes spread­ing, ovate, 2–6 mm, free portions of plicae triangular, entire or shallowly erose-serrate; anthers distinct. Seeds not winged. 2n = 36.

Phenology: Flowering summer.
Habitat: Moist to wet alpine and arctic tundra, meadows and heathland, wet ledges, lake and stream banks, along animal trails.
Elevation: 0–3900 m.

Distribution

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Alta., B.C., N.W.T., Yukon, Alaska, Calif., Colo., Idaho, Mont., Oreg., Utah, Wyo., restricted to high elevations southward, Eurasia (Alps, Caucasus e to Afghanistan).

Discussion

Because of its restriction to high altitudes in much of its range, populations of Gentiana prostrata are widely scattered. Reports of G. prostrata from Nevada, New Mexico, and elsewhere in North America outside the range given here have been based on circumscriptions of the species that included G. fremontii.

Molecular phylogenetic studies have indicated that the North American plants here included in Gentiana prostrata should perhaps be treated as a species distinct from European G. prostrata (A. Favre, pers. comm.). The North American plants have been said to differ from the European plants in having four-merous rather than five-merous flowers, but four-merous and five-merous flowers occur both in Europe and in North America.

Plants exhibiting the morphological extremes alleged to distinguish the taxa nutans and prostrata in the narrow sense frequently occur within the same population, along with intermediates, especially in the northern parts of the range of Gentiana prostrata in North America, but occasionally as far south as Colorado and Wyoming. The character states alleged to distinguish these taxa are not consistently associated in syndromes (studies for this flora, especially specimens at A). What appear to be nodding flowers are often late-stage buds, with the flowers on the same plants becoming erect at anthesis. The relationship between floral orientation in this spe­cies and the time of day or cloudiness has not been stud­ied but may also be relevant. The length of the gyno­phore at maturity, emphasized by W. A. Weber and R. C. Wittmann (1985) in distinguishing G. nutans Bunge from G. prostrata, varies greatly within G. prostrata. No correlation between gynophore length and other traits alleged to distinguish G. nutans were observed in studies for this flora.

The corollas of Gentiana prostrata and G. fremontii close not only at night and in cloudy weather but also when the flower is touched or the stem is jarred.

Selected References

None.

Lower Taxa

None.