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.)

The name Gentiana linearis var. lanceolata A. Gray was applied originally to plants referable to G. linearis, although the name G. rubricaulis was cited in synonymy. The name G. linearis var. latifolia was applied originally only to G. rubricaulis, but both of these names were applied subsequently to both that species and relatively wide-leaved specimens of G. linearis. This confusion has been responsible in some cases for the rejection of specific status for G. rubricaulis, and for erroneous reports of G. rubricaulis in New York and Vermont. Reports from Nebraska were based on an old misidentification of G. puberulenta. Reports from Saskatchewan were also based on misidentified specimens. Reports of G. rubricaulis in Maine and New Brunswick are correct, although these populations are disjunct by about 775 km from the easternmost populations in Ontario.

In marked contrast to all other species of Gentiana in eastern and central North America, including G. linearis, the involucral leaves of this species are strongly ascending and somewhat conduplicate as well as being wider, and envelop the proximal portion of the flower cluster.

In the vicinity of Lake Superior, where the ranges of Gentiana rubricaulis and G. linearis overlap, these species maintain their distinctness, with G. rubricaulis occurring in calcareous soils and G. linearis in granitic and similar strongly acid soils (J. S. Pringle 1968). A few hybrids of G. rubricaulis with G. andrewsii, which is likewise a calciphile, are known. These hybrids have been designated G. × grandilacustris J. S. Pringle.

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