1. Eustoma exaltatum (Linnaeus) Salisbury ex G. Don, Gen. Hist. 4: 211. 1837.
[F]
Gentiana exaltata Linnaeus, Sp. Pl. ed. 2, 1: 331. 1762
Herbs 1.5–10 dm. Leaves glaucous; basal blades spatulate-obovate to elliptic-oblong, 2–10 cm × 5–20 mm, apex obtuse; cauline blades elliptic-oblong to lanceolate or narrowly ovate, 1.5–9(–14) cm × 4–30(–50) mm, distal blades with apices acute to acuminate. Inflorescences: pedicels 3–10 cm. Flowers: calyx 10–25 mm, lobes subulate to linear, apex acuminate; corolla predominantly pale to deep violet-blue or rarely rose-violet, with successive zones of greenish yellow, darker and paler shades of the predominant color in the throat, or rarely white or pale yellow, 1.8–7 cm, lobes elliptic to obovate, apex rounded to subacute, often mucronate.
Subpecies 2 (2 in the flora): United States, Mexico, West Indies, Central America; introduced in n South America and Pacific Islands (Guam).
Whether plants of Eustoma exaltatum are annual, biennial, or perennial depends on the amount and distribution of rain during the growing season.
Although the two subspecies recognized here have often been treated as distinct species, observations and measurements in studies for this flora indicate that variation in plant size, leaf shape, flower size, and corolla-lobe shape is essentially continuous and exhibits less correlation with geographic distribution than has been indicated in some publications. Many specimens from New Mexico and Oklahoma, especially, are intermediate in morphology.
