19. Solidago riddellii Frank ex Riddell
Oligoneuron
riddellii (Frank ex
Riddell) Rydb.
Pl. 237 e, f;
Map 1008
Plants with the
rootstock short and branched, sometimes producing short-creeping, stout
rhizomes. Stems 1 to several, 40–100 cm long, erect or ascending, with several
fine, longitudinal ridges or grooves, glabrous below the inflorescence (where
scattered, inconspicuous, short hairs sometimes occur), somewhat shiny. Leaves
basally disposed, often withered at flowering (additional rosettes usually
present adjacent to the flowering stem), the papery remains often persistent.
Basal and lowermost stem leaves with the blade 8–25 cm long, 0.8–1.5 cm wide,
more than 10 times as long as wide, narrowly oblanceolate to linear, relatively
stiff and folded longitudinally along the midvein, long-tapered to a more or
less long-petiolate, winged base, angled or tapered to a sharply pointed tip,
the margins entire but minutely roughened, the surfaces glabrous, the
undersurface usually with 3–7 faint to conspicuous main veins. Median and upper
stem leaves 2–8(–12) cm long, linear (the uppermost often narrowly lanceolate),
sessile or with a short, poorly differentiated petiole, otherwise similar to
the lower stem leaves. Inflorescences terminal panicles (or sometimes appearing
as a dense terminal cluster), appearing flat-topped or shallowly rounded in
overall outline, the heads solitary or in small clusters at the branch tips.
Involucre 4.5–6.0 mm long, the bracts in 3–5 unequal series. Involucral bracts
linear to narrowly oblong, rounded to broadly and bluntly pointed at the
appressed-ascending tip, the pale margins slightly irregular and/or finely
hairy (but sometimes curled under), the outer surface glabrous, pale yellow to
straw-colored toward the base, with an oblong to elliptic or somewhat
diamond-shaped green area toward the tip, the midvein usually thickened or
keeled, the 1 or 2 pairs of additional veins often faint. Receptacle naked. Ray
florets 7–9, the corollas 5–6 mm long, yellow. Disc florets 6–10, the corollas
4.5–5.5 mm long, the lobes 0.7–1.5 mm long, yellow. Pappus 3.5–4.5 mm long,
most of the bristles slightly thickened toward the tip. Fruits 1.5–2.2 mm long,
narrowly obovoid, glabrous or with a few hairs along the ribs. 2n=18.
August–October.
Scattered to
uncommon in the Ozark and Ozark Border Divisions (North Dakota to Arkansas east
to Michigan and Ohio; apparently disjunct in Georgia). Fens and calcareous
seeps along streams.
This attractive
species is an indicator of high-quality calcareous seepage wetlands, especially
fens.