6. Helianthus hirsutus Raf. (hairy sunflower, bristly sunflower)

H. hirsutus var. stenophyllus Torr. & A. Gray

H. hirsutus var. trachyphyllus Torr. & A. Gray

Pl. 282 a, b; Map 1193

Plants perennial herbs, with slender to stout, usually long-creeping, branched rhizomes (the branches sometimes slightly thickened at the tip but not with well-defined tubers), sometimes occurring in dense colonies. Stems usually solitary, 60–150(–200) cm long, sparsely to more commonly moderately or densely pubescent with short, stiff, loosely ascending, sometimes pustular-based hairs, sometimes nearly glabrous toward the base, not glaucous. Leaves well developed along the stem (usually with 8–20 nodes), usually all opposite, mostly with a well-differentiated, short petiole (the petioles of the larger leaves 0.5–1.5 cm long). Leaf blades 4–18 cm long, 0.7–6.0(–9.0) cm wide, relatively thick-textured, narrowly lanceolate to ovate (mostly 2–7 times as long as wide), flat, not folded longitudinally, rounded to angled or short-tapered at the base, tapered to a sharply pointed tip, the margins finely toothed to entire, flat, the upper surface moderately to strongly roughened with moderate to dense, minute to short, stout, sometimes pustular-based hairs, the undersurface moderately to densely pubescent with somewhat softer, loosely appressed to more or less spreading hairs, also with sparse to moderate, sessile, yellow glands, with 3 main veins, the lateral pair branching from the midnerve at or near the base of the blade, arching upward. Inflorescences of solitary terminal heads or appearing as open clusters or rarely open panicles. Involucre 8–14 mm long, 10–25 mm in diameter, about as long as or slightly longer than the tips of the disc corollas, the bracts in 3 or 4 subequal, overlapping series, narrowly lanceolate to lanceolate, tapered to a sharply pointed, loosely ascending to spreading or recurved tip, the margins with an irregular fringe of short, spreading to ascending hairs, the outer surface glabrous or sometimes sparsely to moderately pubescent with short, stout, ascending hairs, but usually lacking minute, sessile, yellow glands. Receptacle convex to short-conical, the chaffy bracts 7–9 mm long, narrowly oblong to narrowly oblong-oblanceolate, usually with 3 short, sharply pointed lobes at the tip, these green or straw-colored, the outer surface minutely hairy, especially toward the tip. Ray florets 10–15, the corolla 1.5–3.0 cm long, the outer surface usually with sparse, minute hairs and scattered, minute, sessile, yellow glands. Disc florets with the corolla 5.5–6.5 mm long, the corollas yellow, the lobes often minutely hairy on the outer surface. 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 3.5–4.5 mm long, wedge-shaped to obovate, somewhat flattened and more or less bluntly 4-angled in cross-section, the surface glabrous or with a few minute hairs at the tip, uniformly brown or with fine, darker and lighter brown mottling. 2n=68. July–October.

Scattered nearly throughout the state (eastern U.S. west to Minnesota, Nebraska, and Texas; Canada, Mexico). Mesic to dry upland forests, savannas, upland prairies, sand prairies, ledges and tops of bluffs, and banks of streams, rivers, and spring branches; also pastures, quarries, ditches, railroads, roadsides, and disturbed areas.

Heiser et al. (1969) stated that this is a morphologically variable species that some earlier authors had divided into three varieties, based on supposed differences in pubescence patterns and leaf shape. They mentioned that H. hirsutus may have been involved in the parentage of H. tuberosus and discussed the problems of distinguishing some specimens of H. hirsutus from H. divaricatus and H. strumosus. In Missouri, especially in the Ozarks, many specimens collected in relatively dry, partially sunny sites appear somewhat intermediate between H. hirsutus and especially H. strumosus. In fact, H. hirsutus appears to some extent to be the name of last resort applied by botanists to perplexing plants that do not key well. A detailed investigation of genetic and cytological variation within and among populations of upland perennial sunflowers in the Midwest will be necessary to tease apart the confusing patterns of morphological variation that have confounded specimen identifications for many plants within portions of the region.