8. Gentianella quinquefolia (Linnaeus) Small, Fl. S.E. U.S. 929. 1903.
[E F]
Stiff gentian, ague-weed, gentiane de cinq feuilles
Gentiana quinquefolia Linnaeus, Sp. Pl. 1: 230. 1753; G. quinqueflora Hill; Aloitis quinqueflora (Hill) Rafinesque
Herbs annual or biennial, 2–80 cm. Stems erect, usually branched distally but without long branches near base. Leaves: basal usually withered by flowering, blades spatulate to oblanceolate, 5–35 × 2–12 mm; cauline blades ovate, 5–60(–80) × 2–35(–45) mm. Inflorescences terminal and often axillary, dichasial or partly umbelloid cymes; pedicels 1–17 mm. Flowers 5-merous; calyx 2–15 mm, lobes subulate to lanceolate or linear-oblong, usually subequal, (1–)2–8(–10) mm; corolla violet, violet-blue, blue, or occasionally pale yellow or white, narrowly funnelform, opening narrowly, 10–25 mm, lobes incurved, ovate-triangular, 3–8 mm, apex short-attenuate, without adaxial scales or fringes; ovary stipitate.
According to C. T. Mason and H. H. Iltis (1966) Gentianella quinquefolia is at least sometimes a biennial in Wisconsin, whereas elsewhere it has been reported to be an annual. Of the many flowers often present on a single plant, only a few may have open corollas at any one time.
Subspecies 2 (2 in the flora): c, e North America.
The differences between the subspecies of Gentianella quinquefolia often have been overstated. Although the subspecies are largely separated geographically, plants intermediate in morphology are common throughout much of the range of the species. To some degree, the extremes probably represent phenotypic responses to local environmental conditions.
