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.)

Gentiana catesbaei is believed to be extirpated from New Jersey and Pennsylvania. Specimens from Alabama have been reidentified as G. saponaria as all such specimens seen in studies for this flora had the elliptic leaves and short calyx lobes typical of G. saponaria rather than the ovate leaves and much longer calyx lobes that characterize G. catesbaei.

From the more widely distributed Gentiana saponaria, G. catesbaei differs most conspicuously in its ovate rather than elliptic leaves, widest proximal to rather than near mid-length; calyx lobes widest near mid-length and usually 1.5–3 times as long as the tube; and generally with spreading rather than incurved corolla lobes.

Gentiana catesbaei is almost entirely restricted to the Atlantic coastal plain, where it displaces the closely related G. saponaria south of northeastern North Carolina. In the northern part of its range, where the ranges of these species overlap, they generally remain distinct, although a few plants apparently of hybrid origin have been found. A hybrid with the much less similar G. villosa is also known.

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