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.)

In contrast to the deep green stems and leaves of Gentiana prostrata, the vegetative parts of G. fremontii are much paler. G. Engelmann (1879) described plants of G. fremontii as having a pale, sickly appearance, and J. A. Ewan annotated specimens as having been yellowish when seen in the field, reminiscent of a fungus or broomrape (Aphyllon or Orobanche). This suggests that mycorrhizal symbiosis is especially significant in this species, but its trophic ecology has not been studied.

Gentiana fremontii differs further from G. prostrata in having obovoid capsules less than twice as long as wide, generally not fully exserted from the marcescent corolla, narrowly winged distally along the sutures, with valves that eventually separate nearly to the base, whereas the capsules of G. prostrata are compressed-cylindric, more than twice as long as wide, often fully exserted at maturity, not winged, with the valves separating only above the middle. Also, although both species vary in this respect, G. fremontii more often has the flower parts in fives.

The names Gentiana aquatica Linnaeus and Chondrophylla aquatica (Linnaeus) W. A. Weber have often been applied to this species. Gentiana fremontii, although similar to the Siberian and Chinese G. aquatica, appears to differ consistently in the wider, more conspicuous white margins of its leaves, longer and proportionately narrower mid-cauline leaves, usually white rather than blue corollas, and corolla plicae that generally have jagged rather than entire summits. The illegitimate name G. humilis Steven 1812, not Salisbury 1796, has also been applied to G. fremontii, but the North American plants are not now considered conspecific with the type from Azerbaijan.

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