Amsonia palmeri
Amsonia
Palmer's bluestar
blue-star
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.
usually erect and clumping, unarmed, glabrous or pubescent with eglandular hairs.
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.
deciduous, alternate or subverticillate, petiolate or sessile, reduced in size toward stem base, usually at least slightly heteromorphic with branch leaves proportionately narrower than main stem leaves;
stipular colleters absent;
laminar colleters absent.
terminal, thyrsoid or corymbose cymes, distal branches occasionally terminated by small inflorescences that almost never set fruit, pedunculate.
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.
calycine colleters absent;
corolla blue to purplish, white, or lavender (pink), salverform, aestivation sinistrorse;
corolline corona absent;
androecium and gynoecium not united into a gynostegium;
stamens inserted near top of corolla tube;
anthers not connivent, not adherent to stigma, connectives not appendiculate, locules 4;
pollen free, not massed into pollinia, translators absent;
nectary absent or annular.
follicles, paired, brown, slender, terete or moniliform, smooth, glabrous or rarely with patchy indument.
6–10 × 1–2.5 mm.
cylindric, fusiform, or ± terete, not winged, not beaked, not comose, not arillate.
erect, 2–10(–13) cm × 2–4 mm, apex acuminate, glabrous.
= 11.
Amsonia palmeri
Amsonia
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.)
Species 17 (15 in the flora).
Amsonia is taxonomically problematic. Species of the southeastern and south-central United States are highly variable with, in some cases, no definitive species or varietal boundaries and persistent nomenclatural issues. Southwestern species are often variable and sometimes very similar to other species. This treatment conservatively maintains the species circumscriptions that were favored by S. P. McLaughlin (1982), except as noted. Three subgenera are recognized in this treatment, reduced from four in some recent literature. The southwestern subg. Articularia and Sphinctosiphon are most distinguishable in fruit, at which time some species of subg. Sphinctosiphon are hard to distinguish from one another.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Corolla tubes broadest at apex, not constricted; stigmas depressed-capitate to truncate; bracts on distal portions of inflorescences usually inconspicuous, to 2.5 mm, narrowly deltate to deltate or ovate; sc, se United States, Kansas to Virginia, s to e Texas to Florida. | subg. Amsonia |
1. Corolla tubes slightly narrowing to conspicuously constricted at apex; stigmas apiculate with 2 small lobes; bracts on distal portions of inflorescences usually conspicuous, mostly 2–6 mm, linear to narrowly deltate (in A. jonesii usually short, those subtending individual flowers often less than 1 mm or absent); sw United States to c Texas. | → 2 |
2. Stems usually branched for most of length (sometimes only distally); corolla tubes (7–)8–12(–13) mm, moderately to strongly constricted in narrow band just below apex (most visible just before anthesis); mature follicles moniliform, strongly constricted between seeds; seeds fusiform with acute to rounded-acute or flat-truncate (rarely diagonally truncate) ends, with mostly smooth surface. | subg. Articularia |
2. Stems usually branched only on distal portion (sometimes to near base, rarely unbranched); corolla tubes (6–)7.5–41(–45) mm, broadest below apex, slightly narrowing to moderately constricted at apex; mature follicles terete, at most slightly narrowed between seeds; seeds cylindric with diagonally truncate to flat-truncate ends, with mostly convoluted surface. | subg. Sphinctosiphon |
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