Louisiana blue-star

Stems erect, 30–41(–78) cm, glabrous or sparsely pubescent; branches borne on distal portion of stem, much exceeding infruc­tescence (occasionally absent). Leaves: petiole (3–)4–5(–6) mm, moderately to densely (sparsely) pubescent; blades not hetero­morphic; stem leaf blades lan­ceolate, elliptic, or ovate (narrowly elliptic, broadly elliptic, or oblong-lanceolate), (4–)4.8–7.4(–9.5) cm × (10–)12–40(–45) mm, margins entire, not revolute, moderately to densely ciliate, apex acuminate (acute), surfaces densely (to moderately) tomentose abaxially, glabrous adaxially; branch leaf blades similar to stem leaf blades. Flowers: sepals deltate, 0.8–1.1 mm; corolla tube purplish, greenish above, 7–8 mm, lobes blue, 6–8 mm, outer surface of corolla with 5 patches of long trichomes at corolla lobe bases and distal part of tube, less often glabrous. Follicles erect, (6.5–)8.5–10 cm × (2–)3–4 mm, apex acuminate, pubescent at least distally or glabrous. Seeds 9–13 × 1.7–2 mm. 2n = 22.

Flowering spring(–early summer); fruiting summer. Low, wet woods, riparian areas, roadbanks, ditches; elevation range unreported, often apparently low (0–100 m); Ga., La., Miss., Tex.

Amsonia ludoviciana is distinguishable from A. tabernaemontana by its tomentose leaf indument and sometimes distally pubescent follicles, but its distinctiveness has been questioned by some. Almost all of its range is in Louisiana, where it appears to be uncommon yet relatively widespread. Very few collections are known from north-central Georgia, extreme eastern Texas, and southwestern Mississippi (where it is suspected of having been extirpated; no recent collections were seen).