Downy or prairie gentian

Herbs perennial, 1–6 dm, puberulent on stems and abaxially on midveins of leaves and primary veins of calyx tubes. Stems 1–5(–20), terminal from caudex, erect or nearly so. Leaves cauline, ± evenly spaced; blade narrowly oblong-lanceolate, 1.5–7 cm × 4–18 mm, apex obtuse to acute. Inflorescences 1–6-flowered dense cymes or heads, sometimes with additional flowers at 1–3 nodes or on short branches. Flowers: calyx 11–36 mm, lobes linear, 4–18(–25) mm, margins ciliate; corolla deep blue or rarely rose-violet, narrowly campanulate, open, (30–)35–60 mm, lobes spreading or ± recurved, ovate, 6–15 mm, free portions of plicae divided less than 1/2 their length into 2 ± triangular, lacerate segments; anthers distinct. Seeds winged. 2n = 26.

Flowering late summer–fall. Mesic to ± dry savannas and prairies, calcareous soils; 100–1300 m; Man.; Ark., Ill., Ind., Iowa, Kans., Ky., Mich., Minn., Mo., Nebr., N.Dak., Ohio, Okla., S.Dak., Tenn., Wis.

Gentiana puberulenta is evidently extirpated from Ontario, Louisiana, Maryland, and New York, where outlying prairie communities have largely been elimi­nated by agricultural and urban expansion.

The name Gentiana puberula Michaux 1803, not Franchet 1890, and the homotypic synonym Dasystephana puberula (Michaux) Small have long and often been misapplied to this species but are typified by a specimen of G. saponaria.

Some small plants of Gentiana puberulenta appear similar to G. affinis var. affinis, but only a few specimens appear actually to be hybrids between these species. Where their ranges approach each other, the flowers of G. affinis are generally much smaller than those of G. puberulenta, and the corolla lobes of G. affinis are generally less than twice as long as the free portions of the plicae, whereas those of G. puberulenta are more than twice as long. The flower size of G. affinis var. ovata more closely approaches that of G. puberulenta, but in that variety, the range of which does not overlap that of G. puberulenta, the leaves are usually ovate to elliptic rather than narrowly oblong-lanceolate, and the distal internodes are often about as long as or longer than the leaves, in contrast to the proportionately shorter internodes of G. puberulenta. For further guidance in distinguishing between G. puberulenta and G. affinis, see discussion under 13. G. affinis.

Hybrids of Gentiana puberulenta with the strikingly dissimilar G. andrewsii, constituting G. × billingtonii Farwell (as species), and with G. flavida, constituting G. × curtisii J. S. Pringle, occur in the tall-grass prairies. Hybrids with G. saponaria formerly occurred in western Maryland.