Amsonia tomentosa
Amsonia arenaria
gray amsonia, woolly bluestar
erect, 11–65 cm, glabrous or tomentose;
branches usually borne on most of stem (occasionally confined to distal portion), well exceeding infructescence.
erect, 15–71 cm, tomentose;
branches usually borne on most of stem (occasionally confined to distal portion), often exceeding main stem even in flower, always 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 0–1.5(–3) mm, tomentose;
leaf blades slightly heteromorphic;
stem leaf blades linear (ligulate or very narrowly elliptic), (2–)3–6(–7) cm × 1.6–3.5(–5.5) mm, margins entire, not revolute, not ciliate, apex acute (round-tipped), surfaces sparsely to moderately tomentose;
branch leaf blades linear (ligulate, very narrowly elliptic), (2–)2.9–4.5(–6) cm × 1–2(–3.1) mm.
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 subulate (to filiform, aberrantly narrowly deltate), (2–)3–4.5(–5.3) mm;
corolla tube 9–11(–11.5) mm, lobes purple to magenta, maroon, or lavender (blue), (5–)6–8.3(–9.4) mm, outer surface of corolla glabrous.
(8–)11–17 × (3–)3.9–5.5(–6.3) mm.
14–19(–23.5) × 3.6–5 mm.
erect (aberrantly deformed and spreading), 2–8(–9.5) cm × (4–)4.8–6.8 mm, apex acuminate, glabrous (partly tomentose).
erect, 2.9–10.5 cm × 4.8–6.3 mm, apex acuminate, usually somewhat tomentose on one side and near base (glabrous).
Amsonia tomentosa
Amsonia arenaria
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.)
S. P. McLaughlin (1982) included Amsonia arenaria within A. tomentosa var. stenophylla, along with narrow-leaved populations of A. tomentosa from Arizona and Utah. The geographic range of the latter group is almost contiguous with that of the broader-leaved A. tomentosa var. tomentosa, which is native to southern California and Nevada and western Arizona, and both of those groups share features such as an intermingling of glabrous and densely tomentose individuals within single populations. By contrast, the populations of southern New Mexico, western Texas, and northern Mexico formerly termed A. arenaria are geographically disjunct. They are also morphologically distinctive, often having very long distal branches at flowering; consistent moderate leaf pubescence, rather than dense or no pubescence; more pronounced narrowing of leaves than in var. stenophylla; a usually different pattern of calyx indument; and, according to available label notes and photographs, usually different flower colors. Single-seeded fruits are relatively common in A. tomentosa but rare in A. arenaria, and the fruits of A. arenaria are usually somewhat tomentose only on one side and near the base, a state that is rare although not unknown in A. tomentosa. The seeds of A. arenaria are somewhat longer on average. These differences are at least equal in magnitude to those differentiating other pairs of commonly recognized species in this problematic genus. Thus, the continued recognition of A. arenaria at the species level is preferable.
(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 |
CA
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