Solidago riddellii
Solidago gigantea
Riddell's goldenrod
buffalo-bur, giant goldenrod, late goldenrod, smooth goldenrod, tall or giant or smooth goldenrod, verge d'or géante
1–10+, erect, glabrous.
1–20+ or clustered, erect, glabrous or sparsely strigose in arrays, sometimes glaucous.
basal and proximal cauline usually withering by flowering (other rosettes may be present), tapering to long, winged petioles, blades often recurved, linear- lanceolate or -oblanceolate, 100–240 × 8–16 mm, folded along midrib (V-shaped in cross section), bases usually with (2–)3–8 prominent lateral nerves, apices acute to obtuse, faces glabrous;
mid to distal cauline sessile, blades recurved, linear-lanceolate, 50–70 × 8–11 mm, reduced distally, folded, bases with prominent lateral nerves.
basal 0;
proximal cauline usually withering by flowering time, sessile, lanceolate, 91–97 × 10–14 mm, margins sharply serrate, 3-nerved, apices acuminate, abaxial faces pilose on nerves or glabrous;
mid to distal cauline similar, 57–76 × 0.7–1.2 cm, largest toward mid stem, decreasing distally.
2.8–4 mm, moderately short-hispido-strigose, lanceolate bracteoles 0–1.
1.5–3 mm, sparsely to densely strigillose;
bracteoles 0–2, linear-lanceolate.
narrowly campanulate, 4.5–6 mm.
campanulate, (2–)2.5–4(–5) mm.
7–9;
laminae 4.5–5.5 × 0.4–0.5 mm.
(7–)9–15(–24) (conspicuous);
laminae 1–3 × (0.1–)0.2–0.4 mm.
6–10;
corollas 4.5–5.2 mm, lobes 0.7–1.8 mm.
(4–)7–12(–17);
corollas (2.5–)3–3.5(–4.5) mm, lobes 0.6–1(–1.4) mm.
(14–18) in 3–4 series, unequal, obtuse, broad, striations weak, obtuse to rounded, glabrous.
in 3–4 series, unequal, acute;
outer lanceolate, inner linear-lanceolate (hexaploids from far west can have minute stipitate glands, especially near base of outer phyllaries and peduncle bracts).
30–450 in corymbiform to somewhat paniculiform with rounded corymbiform branches (robust plants) arrays, branches and peduncles strigillose.
40–600, secund, in broadly secund, pyramidal paniculiform arrays, rarely rhombic or club-shaped, proximal branches divergent, recurved, glabrous-glabrate or strigose, sometimes glaucous.
1.5–2.2 mm, glabrous;
pappi 3.5–4 mm (apically clavate).
1.3–1.5 mm, sparsely strigose;
pappi 2–2.5 mm.
= 18.
=18, 36, 54.
Solidago riddellii
Solidago gigantea
Solidago gigantea is usually the least hairy species of the S. canadensis complex. The stems may be somewhat glaucous and the array is usually somewhat more open than in S. canadensis and S. altissima, and less leafy than S. lepida. Its blooming season begins and ends earlier than S. altissima in eastern North America. The species is diploid, mostly east of the Appalachian Mountains, tetraploid throughout the eastern forest area, and hexaploid on the prairies. The broader-leaved hexaploids on the prairies have been treated as S. shinnersii; G. H. Morton (1984) indicated that the differences are not diagnostic. Reports of hexaploids in the mountains from Alberta, Idaho, Oregon, Washington, and northwestern Wyoming all have minute stipitate glands on the phyllaries, peduncle bracts, and sometimes the distalmost leaves; such plants belong in S. lepida, as do plants from British Columbia. Stems sometimes have 1–2 elongate insect galls near the base (S. Heard, pers. comm.). Although reported from much of Florida, specimens were seen only from Liberty County; all other collections are S. leavenworthii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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