Stems erect, (35–)52–130 cm, glabrous; branches borne on distal portion of stem, much exceeding infructescence. Leaves: petiole 0–3(–4) mm, glabrous; blades slightly heteromorphic; stem leaf blades linear, (5–)7.5–11 cm × 2–3.2(–4.2) mm, margins entire, revolute, not ciliate, apex narrowly acute, surfaces glabrous or sparsely short-pubescent on midrib and veins adaxially; branch leaf blades linear, 5–10.5 cm × (0.8–)1–1.8(–2.4) mm. Flowers: sepals deltate to narrowly deltate, 0.7–1.5 mm; corolla tube blue (to purplish), 6–8 mm, lobes blue (to white, purplish), (4.5–)5.4–7.8 mm, outer surface of corolla glabrous. Follicles pendulous or erect, 7.5–13.8 cm × 2.5–3.4 mm, apex acute, glabrous. Seeds 7.5–11 × 1.6–2.2 mm.
Phenology: Flowering spring; fruiting summer.
Habitat: Stream banks, bottoms, shaley creek beds, gravel bars and spits, moist glades.
Elevation: 100–400 m.
Discussion
Amsonia hubrichtii resembles A. ciliata var. filifolia but is a much larger plant, with longer, adaxially lustrous leaves, and with narrower ecological preferences. It is confined to central and western Arkansas and southeastern Oklahoma.
Selected References
None.