Amsonia hubrichtii
Amsonia palmeri
Hubricht's bluestar
Palmer's bluestar
erect, (35–)52–130 cm, glabrous;
branches borne on distal portion of stem, much exceeding infructescence.
erect, 23–62(–80) cm, glabrous or moderately (somewhat densely or sparsely) pubescent;
branches usually borne on distal portion of stem (occasionally below midpoint), not or slightly exceeding infructescence.
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.
petiole 0–2(–3) mm, glabrous or moderately (sparsely) pubescent;
blades heteromorphic or all very narrow;
stem leaf blades narrowly oblong-elliptic to narrowly oblong, narrowly lanceolate, or linear, 4.5–7.5(–9.2) cm × 2–18 mm, margins entire, sometimes slightly revolute, moderately short-ciliate if leaf blade is pubescent, apex acute to acuminate, surfaces glabrous or moderately (sparsely) pubescent;
branch leaf blades very narrowly lanceolate or very narrowly elliptic to linear, 3.5–6(–6.8) cm × 1–5(–7) mm.
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.
sepals narrowly deltate to subulate, (2–)3–5(–7) mm;
corolla tube bluish or purplish green or green, 7.5–12(–17) mm, lobes white to blue or yellowish white, (2.5–)3–5(–7) mm, outer surface of corolla glabrous.
7.5–11 × 1.6–2.2 mm.
6–10 × 1–2.5 mm.
pendulous or erect, 7.5–13.8 cm × 2.5–3.4 mm, apex acute, glabrous.
erect, 2–10(–13) cm × 2–4 mm, apex acuminate, glabrous.
Amsonia hubrichtii
Amsonia palmeri
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Leaf morphology and pubescence are quite variable in Amsonia palmeri; if stem leaves are broad, then the plant is noticeably heterophyllous at maturity with narrow branch leaves. Glabrous and pubescent individuals often occur in mixed populations (S. P. McLaughlin 1982). The species can be distinguished from A. tharpii in part by the adaxial base of the corolla lobes being glabrous (vs. frequently pubescent in A. tharpii). Amsonia palmeri is fairly widespread in Arizona, especially in southern and western counties, but is confined to limited portions of southwestern New Mexico and western Texas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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