Amsonia salicifolia Pursh, Fl. Amer. Sept. 1: 184. 1813; A. tabernaemontana var. gattingeri Woodson

Stems erect, 41–94 cm. Leaves: petiole 2–6(–9) mm, glabrous or sparsely pubescent; stem leaf blades narrowly lanceolate to lanceolate (or narrowly elliptic when young), (4–)6.5–10(–11.5) cm × 10–22(–25) mm, margins entire, sometimes irregular, often somewhat revolute, sometimes ciliate, apex acuminate to narrowly acute, surfaces glabrous (sparsely pubescent abaxially and rarely adaxially). Flowers: sepals deltate (narrowly deltate), (0.4–)0.6–1.1(–1.6) mm, glabrous; corolla tube (6.5–)7–8(–8.8) mm, lobes (5–)6–9.5(–12) mm. Follicles erect (rarely spreading), (5–)7–12.5 cm × 2.5–3.5 mm. Seeds 8–10.8 × 1.8–2.4 mm.

Flowering spring(–early summer); fruiting summer(–fall). Woods, prairies and meadows, flood plains, creek beds and gravel bars, roadsides; 30–600 m; Ala., Ark., Ga., Ill., Ind., Kans., Ky., La., Miss., Mo., N.C., Ohio, Okla., S.C., Tenn., Tex., Va.

Variety salicifolia is found in much of the same range as the broad-leaved var. tabernaemontana, which likewise has short, glabrous sepals. Although the ranges of leaf breadth in those two varieties do overlap to some extent, there is (for the most part) an apparent discontinuity between narrow-leaved and broad-leaved populations. In addition, the leaves of var. salicifolia are more often glabrous and more likely to have revolute margins, and the flowers on average are longer than those of var. tabernaemontana; therefore, continued recognition of two varieties seems appropriate. Variety salicifolia strongly resembles var. illustris, which like­wise often has long, narrow leaves; var. illustris has typically longer, pubescent sepals, and its range is much narrower. All varieties may be dubiously distinct where they occur sympatrically.

Variety gattingeri was named by Woodson to include plants with pubescent leaves, especially on the midrib adaxially, although becoming glabrate in maturity. The variety putatively ranges from Indiana to Kansas and south to Tennessee, Arkansas, and Texas. It is not clearly distinguished from var. salicifolia.