Eurybia avita
Eurybia sibirica
Alexander's Rock aster
arctic aster, Siberian aster, Siberian wood-aster
1–5+, erect to ascending, simple, strict, slender, stiff, proximally glabrous or glabrate, distally hirtello-puberulent.
1–5+, usually ascending, sometimes decumbent, often purplish, sometimes branched basally, flexuous, proximally sparsely villous, distally usually densely villous, sometimes lanate.
basal and cauline, firm, blades (1-nerved) linear to lance-linear or oblong-linear (grasslike), 25–140+ × 2–5 mm, ± coriaceous, bases sheathing, margins entire to remotely serrulate-spinose, indurate, remotely scabrous, spines thickened, apices acute, revolute, faces glabrous;
basal and proximal cauline often withering by flowering, bases marcescent, ± long-petiolate;
mid and distal progressively sessile and reduced.
cauline (dark green abaxially, paler grayish green adaxially), firm, ± markedly veined, margins coarsely and sometimes irregularly serrate, sometimes (distal) serrulate or entire, villoso-ciliate, teeth mucronate, slightly incurved, apices obtuse to acute, mucronate, abaxial faces glabrescent to scabridulous, sparsely villous along veins, adaxial sparsely to ± densely villous or villoso-strigose;
proximal winged-petiolate to sessile, petiole bases sheathing, blades spatulate, obovate to oblanceolate, or ovate (smaller than mid), 9–50 × 3–22 mm, bases attenuate to tapering and (in sessile) subclasping;
mid short-petiolate to subpetiolate or sessile, blades lanceolate to lance-ovate, oblong to oblanceolate, or obovate to spatulate, 25–95 × 6–35 mm, gradually reduced distally, bases rounded or subauriculate to widely attenuate or cuneate;
distal (arrays) sessile, lanceolate, lance-ovate, or elliptic to oblanceolate, 8–60 × 1–12 mm, rapidly reduced distally.
densely hirtellous;
bracts 1–2, usually immediately subtending heads.
villous;
bracts 0–3, sometimes immediately subtending heads, lanceolate or spatulate to linear-lanceolate, leaflike or phyllary-like distally (bases indurate, margins purplish), mostly foliaceous, villous.
cylindro-campanulate, 7–9 mm, shorter than pappi.
campanulate, 6–9 mm, shorter than pappi.
8–20;
corollas bluish white to lavender or deep violet, 5–10 × 1–1.7 mm.
12–50;
corollas white to pale violet or purple, 7–17.5 × 0.8–1.8 mm.
15–45;
corollas yellow, 5.5–7 mm, barely ampliate, tubes shorter than narrowly funnelform throats, lobes erect, triangular, 0.6–0.7 mm.
25–125;
corollas yellow becoming purplish, 5–8.1 mm, slightly ampliate, tubes longer than funnelform throats, lobes erect, triangular, 0.5–1.1 mm.
30–55+ in 4–5 series, unequal, chartaceous, bases indurate, margins narrowly hyaline, scabrous, erose, fimbriate, apices appressed or reflexed, acute, sometimes acuminate (some outer), mucronate, marginally thickened, faces glabrous;
outer lance-oblong, rounded, apical zones dark green, flat;
inner linear-oblong, apical zones pale green, restricted to broadly acute tips.
30–80 in 3–4(–5) series, sometimes wholly purplish, usually ± oblong-lanceolate to oblanceolate, sometimes linear-lanceolate (innermost), subequal or ± unequal, membranous, bases indurate, ± rounded, dark green zones lanceolate or truncate at base, in distal 1/3–4/5+ (outer, often foliaceous, sometimes bractlike and surpassing involucres) to 1/4–2/3 (inner), margins hyaline, often purplish, narrowly scarious, erose, densely villoso-ciliate, apices squarrose, acute, apiculate, faces villous.
3–15+ in narrow, flat-topped corymbiform arrays.
1–50, borne singly or in open corymbiform arrays.
tan, fusiform, ± compressed, ca. 5 mm, ribs 7–10(–12) (stramineous, broad), strigillose;
pappi of cinnamon to sordid bristles 5.5–6 mm, equaling disc corollas.
brown, fusiform, compressed, 2.5–3.7 mm, ribs 7–10 (stramineous), faces strigillose;
pappi of dark cinnamon or reddish tan (sometimes apically clavellate) bristles 5.5–7.5 mm, ± equaling disc corollas.
= 18.
= 18.
Eurybia avita
Eurybia sibirica
Of conservation concern.
Eurybia avita is known from Stone Mountain (the type location, where it is now extirpated according to R. Kral 1983, vol. 2) and granite flatrocks in Georgia, and from Pickens County in South Carolina, where it is imperiled; it is presumed extirpated from North Carolina (www.natureserve.org). Kral mapped the species; he underlined its similarities to both E. surculosa and E. paludosa and the need for further studies of its relationships.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Eurybia sibirica is known from the northern Rocky Mountains and the northern Pacific Coast northward, becoming frequent in Alaska, Yukon, and in the boreal forest region of the continental Northwest Territories; it crosses into Siberia to reach Scandinavia (R. Elven 1989). In British Columbia, northern individuals belong to E. sibirica, not E. pygmaea (contra G. W. Douglas et al. 1998–2002, vol. 1), and southern specimens sometimes are E. merita. G. L. Nesom (1994b) recognized three varieties, two of which have been reported from North America (var. sibirica and var. gigantea). At present, however, given the great phenotypic plasticity of this species, it appears preferable not to recognize varieties, pending studies on the validity of these entities. Eurybia sibirica has often been confused at its southern range limit with E. merita, from which it differs by its often more low-cespitose habit (versus more erect habit, but smaller individuals may be similar in this respect), usually more serrate leaves (versus subserrate to nearly entire), and subequal, foliaceous, purplish phyllaries (versus unequal, non-foliaceous, purple-margined). At the southern end of its range, near the Canada–United States border, E. sibirica is usually found at higher elevations than its congener, there at its northern limit. Aster sibiricus forma albinus Lepage is merely a color variant of the species and is not recognized here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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