Flora of North America species comparison

Gentiana puberulenta is evidently extirpated from Ontario, Louisiana, Maryland, and New York, where outlying prairie communities have largely been eliminated by agricultural and urban expansion.

The name Gentiana puberula Michaux 1803, not Franchet 1890, and the homotypic synonym Dasystephana puberula (Michaux) Small have long and often been misapplied to this species but are typified by a specimen of G. saponaria.

Some small plants of Gentiana puberulenta appear similar to G. affinis var. affinis, but only a few specimens appear actually to be hybrids between these species. Where their ranges approach each other, the flowers of G. affinis are generally much smaller than those of G. puberulenta, and the corolla lobes of G. affinis are generally less than twice as long as the free portions of the plicae, whereas those of G. puberulenta are more than twice as long. The flower size of G. affinis var. ovata more closely approaches that of G. puberulenta, but in that variety, the range of which does not overlap that of G. puberulenta, the leaves are usually ovate to elliptic rather than narrowly oblong-lanceolate, and the distal internodes are often about as long as or longer than the leaves, in contrast to the proportionately shorter internodes of G. puberulenta. For further guidance in distinguishing between G. puberulenta and G. affinis, see discussion under 13. G. affinis.

Hybrids of Gentiana puberulenta with the strikingly dissimilar G. andrewsii, constituting G. × billingtonii Farwell (as species), and with G. flavida, constituting G. × curtisii J. S. Pringle, occur in the tall-grass prairies. Hybrids with G. saponaria formerly occurred in western Maryland.

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

Because of the relatively late recognition of Gentiana austromontana as a distinct species, specimens of this species have been identified both as G. clausa and as G. decora. Gentiana austromontana is distinguished from G. andrewsii, G. clausa, and G. latidens by the combination of puberulent stems and calyx tubes with free portions of the corolla plicae that are about as long as the lobes and about twice as wide, divided into two more or less triangular segments each similar to a true lobe in size and shape. Because of its puberulence, it has been confused with G. decora, which differs in its more open, generally paler corollas with longer lobes and plicae, and usually narrowly linear calyx lobes.

Both Gentiana austromontana and G. decora occur in the higher elevations of eastern Tennessee and western North Carolina, although G. decora tends to occur in shadier habitats. These species are usually distinctly dissimilar, in each case bearing a greater resemblance to other species than to each other, but populations of plants variously intermediate between the two occur relatively frequently, especially in Greene and Unicoi counties, Tennessee. Plants otherwise typical of G. austromontana but with narrowly open corollas have been found in Mount Jefferson State Natural Area, Ashe County, North Carolina, and may be derived from introgression of genetic material from G. decora. Gentiana austromontana also hybridizes occasionally with G. clausa.

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