1. Helianthus angustifolius L. (narrow-leaved sunflower)
Pl. 280 a, b;
Map 1188
Plants perennial
herbs, with a short, clumped rootstock, with rhizomes absent or very short, not
occurring as colonies of stems. Stems usually solitary, 50–170 cm long,
moderately pubescent with slender, mostly loosely ascending, minutely
pustular-based hairs, these often sparser above the stem midpoint, not
glaucous. Leaves relatively numerous and well developed along the stem (usually
more than 30 nodes), mostly alternate, sessile or nearly so (sometimes also
with petiolate basal leaves to 2 cm wide). Blades of the stem leaves 3–20 cm
long, 0.1–1.0(–1.5) cm wide, linear or those of the lowermost leaves sometimes
narrowly lanceolate (mostly 7–20 times as long as wide), not folded
longitudinally, mostly short-tapered at the base, tapered to a sharply pointed
tip, the margins entire, mostly curled under, the upper surface moderately
roughened with stiff, pustular-based hairs (these often shed, leaving only the
expanded base), the undersurface usually pale green, moderately to densely
pubescent with somewhat tangled, soft, easily shed hairs, both surfaces often
also with scattered, sessile, yellow glands, with 1 main vein. Inflorescences
of solitary terminal heads or appearing as open, few-headed clusters, the heads
mostly long-stalked. Involucre 8–12 mm long, 12–20 mm in diameter, extending to
about the tips of the disc corollas, the bracts in 2 or 3 subequal series,
lanceolate to narrowly lanceolate, tapered to a sharply pointed, slender,
loosely ascending to more commonly spreading or recurved tip, the margins and
outer surface sparsely to moderately roughened with minute, ascending,
pustular-based hairs and also with sessile, yellow glands. Receptacle shallowly
convex, the chaffy bracts 5.5–6.5 mm long, oblong-oblanceolate, tapered to a
sharply pointed, purplish-tinged, glabrous tip, the outer surface minutely
hairy. Ray florets 10–21, the corolla 1.2–3.0 cm long, minutely hairy and with
sessile, yellow glands on the outer surface. Disc florets with the corolla
4.0–4.5 mm long, the lobes and tip of the tube reddish brown to dark purple
above a sometimes yellowish basal portion. Pappus of 2 scales 1.5–2.0 mm long,
these lanceolate, tapered to a sharply pointed, minute, awnlike tip,
occasionally with an additional pair of thin, irregular apical lobes. Fruits
2–3 mm long, more or less wedge-shaped, flattened but 4-angled in
cross-section, the surface glabrous, finely mottled with dark brown to nearly
black and lighter brown patches. 2n=34. August–October.
Uncommon in the
Mississippi Lowlands Division (southeastern U.S. west to Missouri, Oklahoma,
and Texas). Upland prairies, sand prairies, and savannas; also pastures,
ditches, and roadsides.
Steyermark
(1963) noted that this attractive species does well in cultivation. Although it
has fewer heads per stem and fewer stems per plant than does H.
salicifolius, its poorly developed rhizome system makes it less aggressive
in the garden.