Flora of North America species comparison

The name Gentiana alba Muhlenberg has often been applied to this species. Uncertainty had long persisted, first as to whether the name G. alba was validly published by G. H. E. Muhlenberg in 1813, then, after that publication had been deemed invalid, whether it was validated by T. Nuttall in 1818. A group of nomenclatural authorities considered this issue on behalf of this flora and concluded that neither of those publications of the name G. alba had been valid, and that G. flavida A. Gray was the earliest validly published name for this species (K. N. Gandhi, pers. comm.).

Outlying eastern populations of Gentiana flavida in North Carolina, Pennsylvania, and West Virginia are no longer extant, and the continued existence of other peripheral populations in isolated prairie remnants is precarious. Reports from Manitoba have been based on misidentified G. rubricaulis. A report from Maryland was based on the misreading of a label of a specimen actually from Indiana (studies for this flora).

In contrast to those of the other species of Gentiana in the flora area, with the exceptions of G. clausa and G. latidens, the calyx lobes of G. flavida spread widely, with keels like shelf brackets decurrent on the tube.

Morphological variation in Gentiana flavida should be given further study. According to J. T. Curtis (1959), plants of this species from the northern part of its range, as seen in the field, appear distinctly different in inflorescence form from plants native farther south.

In the tall-grass prairies, Gentiana flavida hybridizes with G. andrewsii, producing G. × pallidocyanea J. S. Pringle, and G. puberulenta, producing G. × curtisii J. S. Pringle. Reports of G. flavida with the corollas distally lilac have been based on plants derived from such hybridization, probably through backcrossing.

(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.)