Solidago sect. Ptarmicoidei
Solidago ptarmicoides
prairie goldenrod, upland white aster, verge-d'or faux-ptarmica, white flat-top goldenrod
1–20+, erect, slender, glabrous proximally, hispid distally.
basal (rosettes) usually present at flowering, largest;
petiole bases or vasculature persisting on rhizomes;
proximalmost cauline petiolate, often present but withered at flowering;
proximal and distal usually with 1 prominent nerve (multiple nerves proximally in S. riddellii).
basal and proximal cauline persistent, subpetiolate to sessile, blades sometimes 3-nerved, linear to linear-lanceolate, 60–100 × 7–10 mm, stiff, flat, margins entire or subentire, faces glabrous or sparsely hairy;
mid to distal cauline sessile, blades linear oblanceolate to linear, 20–40 × 3–5 mm, reduced distally, margins entire.
29–36.5 mm, strigillose;
bracteoles linear.
5–6 mm.
10–20, usually white, rarely pale yellow (conspicuous);
laminae 7–7.3 × 1.4–1.6 mm.
30–36;
corollas 3.8–4.1 mm, lobes 0.5–0.7 mm.
striate with 3–7 nerves (except S. ptarmicoides), eglandular.
in 4–5 series, usually prominently 1-nerved, linear, strongly unequal, outer acute, inner acute to obtuse, glabrous.
in flat-topped to rounded corymbiform arrays, sometimes glomerulate.
1–25(–50), in corymbiform arrays.
(obconic) 1–1.5 mm (ribbed), glabrous;
pappi 3.4–4 mm (apically clavate).
bristles in 2 series (outer not clavate, inner longest, somewhat to strongly clavate).
= 18.
Solidago sect. Ptarmicoidei
Solidago ptarmicoides
Species 6 (6 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
L. Brouillet and J. C. Semple (1981) summarized the morphologic, chemical, cytological, and hybridization data on Solidago ptarmicoides and concluded that, except for the white rays, it is a typical member of sect. Ptarmicoidei. The species hybridizes with S. rigida, S. ohioensis, S. riddellii, and perhaps other goldenrods. It is not known to hybridize with any species of aster (regardless of genus); the supposed Aster × Solidago hybrids are the basis of all reports of intergeneric hybrids in the literature. Horticultural hybrids involving S. ptarmicoides and other Solidago species have been treated as S. ×luteus (M. L. Green ex Dress) Brouillet & Semple (×Solidaster luteus M. L. Green ex Dress). Solidago ×bernardii B. Boivin [Oligoneuron ×bernardii (B. Boivin) G. L. Nesom] is the formal name applied to S. ptarmicoides × S. riddellii hybrids; those have cream rays. Solidago ×lutescens (Lindley ex de Candolle) B. Boivin [Diplopappus lutescens Lindley ex de Candolle; D. albus var. lutescens (Lindley ex de Candolle) Hooker ex Torrey & A. Gray; Aster lutescens (Lindley ex de Candolle) Hooker ex Torrey & A. Gray; A. ptarmicoides var. lutescens (Lindley ex de Candolle) A. Gray; Oligoneuron ×lutescens (Lindley ex de Candolle) G. L. Nesom] applies to hybrids between S. ptarmicoides and S. rigida or S. riddellii from the prairies; these also have cream colored rays.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaves, stems and peduncles moderately to densely short-hairy; distal cauline leaf bladesovate, flat, never folded along midrib | S. rigida |
1. Leaves, stems, and peduncles glabrous or sparsely hairy; distal leaf blades linear to lanceolate, sometimes folded along midrib | → 2 |
2. Rays white (rarely cream); leaf blades linear, stiff, glabrous or sparsely hairy | S. ptarmicoides |
2. Rays yellow; leaf blades linear to linear-lanceolate, stiff or flexible, glabrous | → 3 |
3. Rays 1–4, peduncles usually sparsely to moderately strigillose; Arkansas, Louisiana, Mississippi, Oklahoma, Texas | S. nitida |
3. Rays 6–12, peduncles glabrous or moderately strigillose; Manitoba, midwestern and Great Lakes states s to e Missouri | → 4 |
4. Involucres (5.5–)6–8(–9) mm; proximal and mid cauline leaves usually 3-nerved (sometimes obscurely), the 2 prominent lateral nerves arising proximally and running alongside midnerve for some distance before abruptly diverging; heads usually 10–30(–50)(–100+ rarely, in aberrant plants); plants 30–60+ cm; rays occasionally lighter yellow with age (damp,interdunal hollows, limestone alvars, Michigan, Ontario) | S. houghtonii |
4. Involucres 4–6 mm; mid and distal cauline leaves not 3-nerved or if so then nerves parallel and not abruptly diverging; heads usually (10– on shorter stems)50–400; plants 40–120 cm | → 5 |
5. Leaves flat, only 1 nerve prominent; arrays corymbiform; dunes, marshes, along rivers,Great Lakes area, New York to Illinois and Wisconsin | S. ohioensis |
5. Leaves folded along midrib and with (2–)3–8 prominent nerves at base; arrays somewhat paniculiform with rounded corymbiform branches; moist ground, sw Ontario toWisconsin and se Manitoba, sw to e Missouri | S. riddellii |
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