1. Gentiana alba Muhl. ex Nutt. (pale gentian, white gentian, yellowish gentian)

Gentiana flavida A. Gray

Pl. 419 d; Map 1871

Stems 30–90 cm long, erect or nearly so, glabrous. Leaves glabrous, ovate to lanceolate-ovate, oblong in reduced lower leaves, widest near the bases, 3–10 cm long; leaf margins sometimes minutely denticulate, but not ciliate. Calyces 11–21 mm long, the lobes ovate to lanceolate-ovate, as long as the tube. Corollas white to greenish or yellowish tinged, rarely pale lilac in upper half, open at maturity, narrowly funnelform, 3.5–4.7 cm long. Free portion of the corolla lobes broadly ovate, erect to somewhat incurved, longer than the appendages, 3–6 mm long. Anthers more or less fused to one another. 2n=26. August–October.

Scattered nearly throughout the state (eastern and midwestern U.S.; Ontario). Upland prairies, glades, and openings of mesic upland forests.

A detailed nomenclatural history of this species was presented by Wilbur (1988), but subsequent bibiographic research by James Pringle and others has revealed the existence of an earlier valid combination for the name G. alba than was known to Wilbur.

Gentiana ×pallidocyanea J.F. Pringle, the rare hybrid between this species and G. andrewsii, has been found in several counties, mostly in northeastern Missouri. Its corollas are variable, but generally intermediate in color and relative appendage length between those of its parents. Another hybrid, G. ×curtisii J.F. Pringle (G. alba × G. puberulenta), was documented recently from an upland prairie in Adair county, and also occurs spontaneously at a site in Franklin County where both parental species have become naturalized from seedings a number of years ago.