Amsonia eastwoodiana Rydberg

Plants slightly heterophyllous. Stem leaves: petiole 1–2(–3) mm (leaves rarely sessile); blade narrowly to very narrowly elliptic or narrowly lanceolate, (2.4–)2.8–5(–6) cm × (3–)4–8(–10) mm, base cuneate (nar­rowly convex). Branch leaf blades ligulate to very narrowly elliptic, (2.4–)3–4.7(–5.6) cm × (2–)3–6(–7) mm. Corolla lobes bluish white to white, blue-violet, or blue-lavender.

Flowering spring; fruiting early summer. Sandy soils, arid shrubland and brush communities, rarely on rocky hillsides; 800–1600 m; Ariz., Utah.

Some specimens of var. stenophylla have characters reminiscent of Amsonia arenaria (patchy calyx or fruit indument or flowers said to be somewhat purplish), but on balance, these populations seem to be more naturally grouped with A. tomentosa (see discussion under A. arenaria). Two specimens identified with var. stenophylla from near the putative boundary between its range and that of var. tomentosa have very broad stem leaves (to 15 mm), indicating a likelihood of gene flow or incomplete separation between the two varieties. The synonym A. eastwoodiana was based on a combination of fruiting material of var. stenophylla and flowering material of A. peeblesii but was usually used for populations of var. stenophylla (S. P. McLaughlin 1982).