Gentiana rubricaulis
Narrat. Exp. St. Peter’s River 2: 384. 1824.
Herbs perennial, 1–8 dm, glabrous. Stems 1–5, terminal from caudex, erect. Leaves cauline, gradually more widely spaced distally; blade linear to oblong-lanceolate (proximal) or lanceolate to ovate (distal), 3–9 cm × 8–30 mm, apex acute. Inflorescences dense 1–15-flowered cymes, basally ± enveloped by ascending, conduplicate involucral leaves, rarely with additional flowers at one node. Flowers: calyx 10–26 mm, lobes oblong, 2–14 mm, margins not ciliate; corolla grayish violet to violet-blue or occasionally rose-violet or white, tubular, loosely closed or slightly open, 30–45 mm, lobes ascending, ovate-triangular, 4–8 mm, free portions of plicae obliquely triangular, erose, with minute, deflexed second segment; anthers connate. Seeds winged. 2n = 26.
Phenology: Flowering late summer–fall.
Habitat: Fens, swamps, wet meadows, stream banks, interdunal depressions, calcareous soils.
Elevation: 0–700 m.
Distribution
Man., N.B., Ont., Maine, Mich., Minn., Wis.
Discussion
The name Gentiana linearis var. lanceolata A. Gray was applied originally to plants referable to G. linearis, although the name G. rubricaulis was cited in synonymy. The name G. linearis var. latifolia was applied originally only to G. rubricaulis, but both of these names were applied subsequently to both that species and relatively wide-leaved specimens of G. linearis. This confusion has been responsible in some cases for the rejection of specific status for G. rubricaulis, and for erroneous reports of G. rubricaulis in New York and Vermont. Reports from Nebraska were based on an old misidentification of G. puberulenta. Reports from Saskatchewan were also based on misidentified specimens. Reports of G. rubricaulis in Maine and New Brunswick are correct, although these populations are disjunct by about 775 km from the easternmost populations in Ontario.
In marked contrast to all other species of Gentiana in eastern and central North America, including G. linearis, the involucral leaves of this species are strongly ascending and somewhat conduplicate as well as being wider, and envelop the proximal portion of the flower cluster.
In the vicinity of Lake Superior, where the ranges of Gentiana rubricaulis and G. linearis overlap, these species maintain their distinctness, with G. rubricaulis occurring in calcareous soils and G. linearis in granitic and similar strongly acid soils (J. S. Pringle 1968). A few hybrids of G. rubricaulis with G. andrewsii, which is likewise a calciphile, are known. These hybrids have been designated G. × grandilacustris J. S. Pringle.
Selected References
None.