Amsonia tomentosa
Amsonia rigida
gray amsonia, woolly bluestar
stiff bluestar
erect, 11–65 cm, glabrous or tomentose;
branches usually borne on most of stem (occasionally confined to distal portion), well exceeding infructescence.
erect (somewhat ascending at base), (34–)48–92(–107) cm, glabrous or seldom sparsely pubescent;
branches borne on distal portion of stem, exceeding infructescence.
petiole 1–5 mm, glabrous or tomentose (leaves rarely sessile);
leaf blades slightly or moderately heteromorphic;
stem leaf blades ovate to narrowly lanceolate, narrowly to very narrowly elliptic, or elliptic, (2–)3–5(–6) cm × (3–)4–27 mm, margins entire, not revolute, not ciliate, apex acute (somewhat acuminate), surfaces glabrous or densely (rarely sparsely) tomentose;
branch leaf blades narrower than stem leaf blades, (2.2–)3–4.7(–5.6) cm × (2–)3–6(–13) mm.
petiole (1–)2–5(–6) mm, glabrous or slightly to moderately pubescent;
blades not heteromorphic;
stem leaf blades elliptic, narrowly oblong, lanceolate, or obovate, (3.1–)3.9–8.4(–9.3) cm × (4–)8–18(–23) mm, margins entire, often slightly revolute, usually irregularly and sometimes appearing dentate, sometimes sparsely ciliate, or moderately scabrous, apex acuminate, sometimes acute, surfaces glabrous or slightly to moderately pubescent on midrib or on veins;
branch leaf blades similar to stem leaf blades.
sepals subulate or narrowly deltate (deltate), (2–)3.5–6(–7.5) mm;
corolla tube green to purplish or pinkish green, (7–)8–12(–13) mm, lobes bluish (violet- to lavender-tinged) to white especially after anthesis (pinkish, bluish, or purple-tinged), (2.8–)4.5–8 mm, outer surface of corolla glabrous.
sepals narrowly deltate to deltate, (0.8–)1–1.5(–1.8) mm;
corolla tube blue, greenish above, (5.5–)6–8(–8.5) mm, lobes blue (to white or rarely lavender), (4–)5–7.5 mm, outer surface of corolla glabrous (very sparsely short-pubescent).
(8–)11–17 × (3–)3.9–5.5(–6.3) mm.
8.5–12(–15) × 1.9–2.6(–3) mm.
erect (aberrantly deformed and spreading), 2–8(–9.5) cm × (4–)4.8–6.8 mm, apex acuminate, glabrous (partly tomentose).
erect (sometimes partly spreading), 9–13(–15) cm × 3–4 mm, apex acute, sometimes elongated, glabrous.
Amsonia tomentosa
Amsonia rigida
Varieties 2 (2 in the flora).
Both varieties of Amsonia tomentosa have an unusual pattern of variation in pubescence. Stems and leaves are usually either densely tomentose or glabrous, with intermediate density of pubescence rare. In some populations, the two forms are found together, suggesting that indument may be a single-gene trait.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Amsonia rigida is very similar to narrow-leaved forms of the more common and widespread A. tabernaemontana, but it can be distinguished by its usually glabrous corolla and leaves with often irregularly revolute margins. Almost all populations from Alabama and Mississippi, primarily from the Black Belt Prairie region, have leaf margins that are ciliate, often with short, sturdy, curved hairs, and often pale flowers. These populations have been informally labeled as a variety or species, but no name has been validly published. Although they are not formally recognized as a variety here, for conservation purposes they should be considered possibly distinct.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stem leaf blades ovate to lanceolate (narrowly elliptic to elliptic), (6–)8–27 mm wide, branch leaf blades markedly narrower, 4–13 mm wide; w, s Arizona, California, Nevada. | var. tomentosa |
1. Stem leaf blades narrowly to very narrowly elliptic or narrowly lanceolate, (3–)4–8(–10) mm wide, branch leaf blades slightly narrower, (2–)3–6(–7) mm wide; n Arizona, Utah. | var. stenophylla |
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