5. Rudbeckia laciniata L. var. laciniata (wild goldenglow, cutleaf coneflower)
Pl. 288 e; Map
1221
Plants
perennial, with fibrous roots and often a somewhat woody rootstock. Stems
50–250 cm long, glabrous, sometimes glaucous. Leaves mostly deeply 1 or
2 times 3(5 or 7)-lobed or deeply divided, the basal and lowermost stem leaves
sometimes fully compound, the uppermost stem leaves sometimes unlobed, mostly
angled or tapered at the base, only slightly expanded at the base and
inconspicuously wrapping around the stem, the margins otherwise entire or
sharply finely to coarsely toothed, the surfaces glabrous or sparsely pubescent
with short, stiff hairs, at least the upper surface smooth to the touch, both
surfaces sometimes somewhat glaucous, green to grayish green when fresh. Basal
and lowermost stem leaves often absent at flowering, long-petiolate, the blade
15–50 cm long, 100–300 mm wide, ovate to broadly ovate in
outline, the lobes ovate to elliptic or obovate, tapered to a sharply pointed
tip. Median and upper stem leaves short- to long-petiolate, the uppermost leaves
occasionally sessile, the blade 3–40 cm long, 1–20 mm wide, the
unlobed leaf blade or the lobes of a divided blade lanceolate to ovate to
elliptic, tapered to a sharply pointed tip. Inflorescences mostly appearing as
loose, open clusters or leafy panicles. Involucral bracts 8–15,
3–15 mm long, oblong-ovate to oblong-lanceolate or narrowly oblong, the
outer surface and margins glabrous or moderately to densely and finely hairy,
especially toward the base. Receptacle 15–20 mm long, 10–20 mm
in diameter, spherical to broadly ovoid at the start of flowering, then
elongating somewhat but remaining spherical to ovoid. Chaffy bracts subtending
only the disc florets, shorter than to nearly as long as the disc florets
(including the corolla), truncate, rounded or broadly angled to a short,
bluntly or sharply pointed tip, the outer surface and margins with dense,
short, often somewhat matted hairs, dull yellow to yellowish green. Ray florets
8–13, the corolla 20–45 mm long, usually relatively slender,
angled downward or drooping at flowering, yellow, the outer surface sparsely
short-hairy. Disc florets numerous, the corolla 3.5–4.5 mm long, dull
yellow to yellowish green, the lobes ascending at flowering. Stigma lobes
relatively short and bluntly to less commonly sharply pointed at the tip.
Pappus a short, toothed crown 0.4–0.8 mm long. Fruits 2.0–3.5
mm long. 2n=38, 54, 72, 102+. July–September.
Scattered nearly
throughout the state, but apparently absent from the Mississippi Lowlands
Division and uncommon in the western portion of the Glaciated Plains (U.S. [except a few western states]; Canada; introduced in Europe). Bottomland forests, mesic upland
forests in ravines, banks of streams and rivers, margins of ponds and lakes,
and sloughs; also roadsides.
Most authors
have accepted between two and five varieties within R. laciniata. The
most distinctive of these is the western var. ampla (A. Nelson)
Cronquist (excluded from the Missouri flora by Steyermark [1963]), which has
receptacles to 3 cm long and to 2 cm in diameter, as well as bigger disc
florets and fruits, and a number of subtle vegetative differences. Some authors
have argued that it is better regarded as a distinct species (Jones, 1957).
Among the eastern varieties, none is particularly distinct, although the Florida endemic var. heterophylla (Torr. & A. Gray) Fernald & B.G. Schub.,
with its unlobed lower leaves and relatively densely hairy leaves and stem
tips, is striking in its extreme form. Missouri plants uniformly are referable
to var. laciniata. It should be noted that at least the plants with
triploid and pentaploid chromosome numbers (2n=54, 102+) apparently are
apomictic, a condition not uncommon in the variety (Cronquist, 1980).
One of the most
common forms of the species in cultivation has been called var. hortensis
L.H. Bailey or cv. ‘Hortensis’, the garden goldenglow, and it has all or most
of the disc florets converted to ray florets. Some of the other plants sold as
cultivars of R. laciniata represent variants developed following hybridization
of R. laciniata with related species such as R. nitida Nutt.
(Dress, 1961).