Stems erect from vertical taproot, (15–)20–58(–90) cm, glabrous; branches often borne below midpoint of stem as well as distally, uppermost often exceeding infructescence, often terminated by small inflores­cences. Leaves: petiole 0–1.2 mm, glabrous; blades moder­ately heteromorphic; stem leaf blades ligulate to narrowly oblong-elliptic or narrowly lanceolate, 3.2–7.3(–9.3) cm × 3–7(–9) mm, margins entire, not (slightly) revolute, not ciliate, apex acute, surfaces glabrous; branch leaf blades linear to very narrowly oblong or lanceolate, 4.1–6.4(–7.4) cm × 1–4(–7) mm. Flowers: sepals narrowly deltate (subulate), (2–)3–6(–9.5) mm; corolla tube purplish blue to greenish, darker and more bluish proximally, (13–)14–17(–19) mm, lobes white, (5–)7–9(–10) mm, outer surface of corolla glabrous. Follicles erect, (2–)3–7(–10) cm × (2.5–)3–4 mm, apex acuminate, glabrous. Seeds (5–)7–11 × 1.5–2.5 mm. 2n = 22.

Flowering spring–early summer; fruiting summer. Ridge tops, valleys, washes and draws, often on sand or sandstone; 1300–1700 m; Ariz.

Amsonia peeblesii generally resembles narrower-leaved, glabrous forms of A. palmeri. The stems of A. peeblesii are much more often branched below the midpoint, and the flowers are usually larger; the dis­tribution of A. peeblesii is narrower and more northerly, whereas A. palmeri is largely found in southern and western portions of Arizona.