9. Helianthus mollis Lam. (ashy sunflower)
H. mollis f. flavidus Steyerm.
Pl. 282 g, h;
Map 1196
Plants perennial
herbs, with relatively thick, long-creeping, branched rhizomes, usually occurring
in colonies. Stems solitary, 50–120 cm long, moderately to more commonly
densely pubescent with short, spreading hairs and usually also shorter,
ascending hairs, these mostly not pustular-based, usually appearing uniformly
grayish, slightly to moderately roughened to the touch, occasionally nearly
glabrous toward the base with age. Leaves well developed along the stem
(usually with 8–17 nodes), all or mostly opposite, sessile or with a minute
petiole less than 5 mm long. Leaf blades 3–15 cm long, 1–7 cm wide, broadly
lanceolate to broadly ovate, rounded or shallowly cordate at the base, tapered
to a usually sharply pointed tip, the margins entire or less commonly finely
toothed, flat, the surfaces moderately to more commonly densely pubescent with short,
slender, curved or ascending hairs, usually appearing uniformly grayish,
slightly to moderately roughened to the touch, often also with sparse to dense,
sessile, yellow glands, with 3 main veins, the lateral pair branching from the
midnerve well above the base of the blade, arching upward. Inflorescences of
solitary terminal heads or appearing as leafy spikes or narrow racemes.
Involucre 7–12 mm long, 20–30 mm in diameter, about as long as or slightly
longer than the tips of the disc corollas, the bracts in 2–4 somewhat unequal,
overlapping series, narrowly lanceolate to lanceolate, tapered to a sharply
pointed, appressed-ascending or somewhat spreading tip, the margins and outer
surface densely pubescent with slender, ascending to somewhat spreading or
tangled hairs, also with moderate to dense, minute, sessile, yellow glands.
Receptacle convex, the chaffy bracts 9–11 mm long, narrowly oblong to linear,
tapered to a sharply pointed, green or straw-colored tip, the outer surface
densely short-hairy and glandular. Ray florets 17–30, the corolla 2.0–3.5 cm
long, glabrous or the outer surface with sparse to dense, short, slender hairs
and often dense, minute, sessile, yellow glands. Disc florets with the corolla
6.0–7.5 mm long, the corollas yellow or rarely pale yellow, the lobes usually
minutely hairy on the outer surface (sometimes only along the margins). Pappus
of 2 scales 2.5–3.5 mm long, these lanceolate to narrowly triangular, tapered
to a sharply pointed, often minutely awnlike tip. Fruits 3–4 mm long,
wedge-shaped to obovate, only slightly flattened but usually bluntly 4-angled
in cross-section, moderately to densely pubescent with short, ascending hairs
when young, only those at the tip persistent at maturity, uniformly dark brown
or with fine, darker and lighter brown mottling. 2n=34. July–October.
Common in the
Unglaciated Plains Division, scattered elsewhere in the state but uncommon or
absent from most of the Glaciated Plains (Wisconsin to Nebraska south to
Louisiana and Texas; introduced in the eastern U.S. and adjacent Canada).
Upland prairies and glades; also pastures, old fields, fencerows, margins of
ditches, railroads, and roadsides.
Helianthus ×cinereus Torr. & A. Gray
var. sullivantii Torr. & A. Gray is a rare morphologically
intermediate hybrid between H. mollis and H. occidentalis ssp. occidentalis.
Steyermark (1963) reported it from a mixed population of the parental species
from Laclede County, and it also has been collected more recently in Howell
County. Because H. occidentalis has the leaves greatly reduced above the
stem base, hybrids derived from it are fairly easily recognizable in the field.
Heiser et al. (1969) also stated that H. mollis hybridizes with a number
of other sunflower species, including a few that occur in Missouri: H.
divaricatus, H. grosseserratus, H. maximilianii, and H. microcephalus.
A single late-season collection made by B. F. Bush in 1893 in Shannon County
may represent a hybrid with H. divaricatus, but otherwise none of these
hybrids has been discovered yet in Missouri, although H. mollis can be
found in proximity to all but the last species in the state.