Symphyotrichum ×amethystinum
Symphyotrichum laurentianum
amethyst aster, aster, hybrid aster
aster du golfe du saint-laurent, Gulf Of St. Lawrence aster
1–5+, erect (light brown to grayish brown), densely hispidulo-hirsute.
1, decumbent to erect (straight), glabrous.
light green, thin to firm;
basal withering by flowering, sessile, blades oblanceolate, 10–40 × 3–10 mm, attenuate, margins usually entire, rarely remotely serrate, piloso-ciliate, apices obtuse, rounded to mucronulate, faces sparsely to moderately strigose;
proximal cauline sometimes persistent by flowering, sessile, blades linear or oblong to elliptic-oblanceolate, 40–60 × 3–10 mm, bases rounded or slightly clasping, margins entire, scabrous, apices acute to obtuse, faces ± copiously hirsute;
distal sessile, blades oblanceolate, 15–45 × 2–3(–4.5) mm, progressively reduced distally, bases cuneate, margins entire, apices acute, white-spine-tipped, faces sparsely strigose.
± fleshy, margins entire, eciliate, apices obtuse, faces glabrous;
basal deciduous at bolting, petiolate, blades oblanceolate 44–50 × 5–7 mm [cult.], bases attenuate;
proximal cauline and some distal withering by flowering;
cauline sessile, blades linear-lanceolate to spatulate, 15–55 × 1–4 mm, reduced distally, bases cuneate;
distal sessile, blades linear-lanceolate to spatulate.
hispid, bracts 1–3+, oblong-lanceolate, 3–5 mm, not grading into phyllaries.
glabrous, bracts linear.
campanulate to hemispheric, 4–6 mm.
campanulate, 5–8+mm.
20–35;
corollas azure blue to violet or lavender, laminae 5–10 × 0.6–1.2 mm.
0.
14–47+ in 2–3+ series;
laminae 0 (corolla tubes 2–2.4 mm, shorter than style branches).
20–30+;
corollas light yellow turning pinkish to purple, 3–4 mm, tubes ca. 1/2 narrowly funnelform throats, lobes triangular, 0.5–0.7 mm, glabrous.
5–8+;
corollas yellow, 3.1–3.9 mm, lobes deltate to triangular, 0.2–0.3 mm.
in 3–5 series, linear-lanceolate, ± unequal to subequal, bases ± indurate, margins hyaline proximally, outer distally hispido-scabrous, green zones diamond-shaped, restricted to distal 1/2–1/4, apices (outer) spreading to reflexed, acute, subspinulose, (inner) acuminate, purplish, faces (outer) scabroso-puberulent or strigose, eglandular, inner distally stipitate-glandular.
in 3–4 series, lanceolate, subequal, bases scarious, margins eciliate, green zones foliaceous (outer), apices obtuse, faces glabrous.
in ample, leafy, paniculiform arrays, branches ascending, sometimes secund (heads often crowded).
(disciform) in ± densely paniculiform arrays.
dull purple or brown, obovoid, not compressed, 1.5–2 mm, 7–9-nerved, faces densely sericeous;
pappi tan to tawny, sometimes rose to violet-tinged, 3.5–5.5 mm.
purple, obovoid, ± compressed, 2.8–2.9 mm, 2–4-nerved, faces strigillose;
pappi white to yellowish white, 4.8–5.2 mm.
= 10.
= 14.
Symphyotrichum ×amethystinum
Symphyotrichum laurentianum
Symphyotrichum ×amethystinum is the F1 hybrid between S. ericoides and S. novae-angliae, encountered sometimes throughout the area where the two parental species co-occur. It is morphologically intermediate; it has non-spiny, sparsely stipitate-glandular phyllaries and rose-violet rays in mid-sized heads. Forma leucerythros Bemis and forma leucos Bemis have been described within this hybrid and may represent recombinants or normal population color variants.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Symphyotrichum laurentianum is known only from the southern shores of the Gulf of St. Lawrence.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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