White prairie or white or cream or yellowish or pale gentian

Dasystephana flavida (A. Gray) Britton

Herbs perennial, 3–10 dm, glabrous. Stems 1–10, terminal from caudex, decumbent to erect. Leaves cauline, ± evenly spaced; blade lanceolate to ovate, 5–15 cm × 15–50 mm, apex acuminate. Inflorescences dense 1–20-flowered cymes, often also with additional clusters at 1 or 2 nodes. Flowers: calyx 10–30 mm, lobes spreading, with bracketlike keels, lanceolate to ovate-triangular, 3–15 mm, margins not ciliate; corolla white, sometimes with yellowish or greenish tinge (drying yellowish), with veins outlined in green, tubular, loosely closed or slightly open, 30–55 mm, lobes incurved to nearly erect, widely ovate-triangular, 4–6 mm, free portions of plicae obliquely triangular, erose to shallowly lacerate, with minute, deflexed second segment; anthers connate or some sooner or later distinct. Seeds winged. 2n = 26.

Flowering late summer–fall. Mesic prairies and savannas, calcareous soils; 100–800 m; Ont.; Ark., Ill., Ind., Iowa, Kans., Ky., Mich., Minn., Mo., Nebr., Ohio, Okla., Pa., W.Va., Wis.

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).

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.).

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.