94. Verbesina L. (crownbeard, wingstem)

Plants annual or perennial herbs (shrubs or trees elsewhere). Stems erect or ascending, unbranched or more commonly several- to many-branched, mostly above the midpoint, with several longitudinal lines or ridges, these often winged, sparsely to densely hairy. Leaves opposite or alternate, sessile or petiolate, the bases sometimes somewhat expanded and wrapping around the stem or decurrent below the attachment point as wings of green tissue. Leaf blades simple, lanceolate to elliptic-lanceolate, ovate, or triangular, tapered to shallowly cordate at the base, angled or tapered to a sharply pointed tip, the margins relatively flat, variously toothed and usually minutely hairy, the surfaces variously hairy, sometimes roughened, not glandular. Inflorescences of solitary terminal heads or more commonly loose, open clusters or panicles, the heads with short to long, usually bractless stalks. Heads radiate (discoid elsewhere). Involucre cup-shaped to somewhat conical or saucer-shaped, the bracts in mostly 1 or 2 (more elsewhere) subequal (the outer series often somewhat shorter), overlapping series. Involucral bracts 9–21, linear to oblanceolate or narrowly ovate, ascending or spreading to reflexed, more or less green, the outer surface variously hairy, not glandular, with usually 1 inconspicuous nerve. Receptacle flat or broadly convex to shallowly conical, not elongating as the fruits mature, with chaffy bracts subtending the ray and disc florets, these narrowly oblong to narrowly oblong-oblanceolate (linear in V. encelioides), somewhat concave or folded, and wrapped around the florets. Ray florets 1–15, sterile or pistillate, the corolla usually showy, relatively broad, yellow or white, not persistent at fruiting. Disc florets 8 to numerous (more than 150), perfect, the corolla yellow or white, not expanded at the base or persistent at fruiting. Style branches with the sterile tip somewhat flattened, elongate and tapered to a sharply pointed tip. Pappus of the disc florets of 2 short awns 0.5–3.5 mm long, that of the rays similar (absent in V. encelioides), more or less persistent at fruiting (usually shed in V. encelioides). Fruits oblanceolate to broadly obovate in outline, flattened, the margins sharply angled or more commonly narrowly to broadly winged, the surface usually with a longitudinal angle or ridge, sometimes also with 1 or 2 additional inconspicuous nerves, finely hairy, dark brown to black, sometimes with fine, lighter mottling, the wings lighter colored, usually not shiny. About 300 species, North America, Central America, South America, Caribbean Islands.

Verbesina is a morphologically variable genus for which a comprehensive modern monograph has yet to be published. Most of the species occur in the American tropics. Our species (especially V. alternifolia and V. virginica) are noted as frequently producing spectacular formations called frost flowers at the end of the growing season. These are created when sudden overnight freezing temperatures cause the stems to burst and release quantities of sap, which freezes into intricate, layered, petal-like shapes of ice sometimes more than 10 cm long (Steyermark, 1963; Swihart, 2000).