Comments
provided by eFloras
Helianthus giganteus was probably introduced in Newfoundland. It intergrades with H. nuttallii and H. grosseserratus; it is distinctive in its hairy, reddish-colored stems, dark anther appendages, and prominent setae on the petioles. The natural hybrid of H. giganteus with H. grosseserratus has been called H. luxurians E. Watson (R. W. Long 1954). Hybrids of H. giganteus with H. divaricatus have been referred to as H. ambiguus (Torrey & A. Gray) Britton and H. ×divariserratus R. W. Long (Long 1954).
- license
- cc-by-nc-sa-3.0
- copyright
- Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
Description
provided by eFloras
Perennials, 100–400 cm (rhi-zomatous). Stems (usually reddish) erect, hairy. Leaves cauline; mostly alternate; petioles 0–1.2 cm (ciliate); blades (3-nerved from bases) lanceolate to lance-ovate, 7–20 × 1.2–3.5 cm, bases cuneate, margins serrulate to subentire (± flat), abaxial faces scabrous or ± hirsute, sometimes gland-dotted. Heads 1–12. Peduncles 8–12 mm. Involucres hemispheric, 10–24 mm diam. Phyllaries 20–25 (loose or spreading), linear, 8–15 × 1.2–2 mm, (margins usually ciliate) apices acute to attenuate , abaxial faces sparsely strigose, not gland-dotted. Paleae 7–9 mm, entire or ± 3-toothed (apices acute, hairy). Ray florets 12–20; laminae (often pale yellow) 15–25 mm (abaxial faces not gland-dotted). Disc florets 60+; corollas 5–6 mm, lobes yellow; anthers dark brown or black, appendages dark. Cypselae 3–4 mm, glabrate; pappi of 2 aristate scales 2.4–3 mm. 2n = 34.
- license
- cc-by-nc-sa-3.0
- copyright
- Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
Synonym
provided by eFloras
Helianthus alienus E. Watson; H. validus E. Watson
- license
- cc-by-nc-sa-3.0
- copyright
- Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA
Helianthus giganteus: Brief Summary
provided by wikipedia EN
Helianthus giganteus, the giant sunflower or tall sunflower, is a species of Helianthus native to the eastern United States and eastern and central Canada, from Newfoundland west to Alberta south to Minnesota, Mississippi, and South Carolina.
- license
- cc-by-sa-3.0
- copyright
- Wikipedia authors and editors