Flora of North America species comparison

Varieties 2+ (1 in the flora).

Gentiana prostrata is variously divided into subspecies and/or varieties. At least two, perhaps more, varieties seem appropriately recognized at that rank (one in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)