Both Helenium autumnale and Helenium bigelovii are herbaceous perennial species within the genus Helenium, a member of the extensive Asteraceae (sunflower) family. Despite their close relationship, they are distinct species with unique taxonomic identities. Helenium autumnale, commonly known as common sneezeweed, is the more widely distributed and type species for the genus. Helenium bigelovii, known as Bigelow's sneezeweed, is named after 19th-century botanist John Milton Bigelow. Their shared common name, "sneezeweed," originates from historical use of the dried leaves in snuff to induce sneezing, believed to expel evil spirits, rather than from any significant allergenic pollen.
The two species exhibit clear differences in their overall structure and leaves. Helenium autumnale is a tall, erect plant, typically reaching heights of 3 to 5 feet (0.9 to 1.5 meters). Its leaves are lanceolate to oblanceolate, with a distinctive winged petiole that runs down the stem (decurrent), and they are often toothed or serrated along the margins. The foliage is generally abundant along the stem. In contrast, Helenium bigelovii is often slightly shorter but more notably, its leaves are primarily basal and oblanceolate, meaning most of the leaves are clustered at the base of the plant. The stem leaves are greatly reduced, smaller, and less numerous, and they lack the strongly decurrent nature of H. autumnale.
The flower heads of both species are composite, consisting of central disc florets surrounded by ray florets, but their details differ. Helenium autumnale produces a profusion of small to medium-sized flowers, typically 1-2 inches (2.5-5 cm) in diameter. The wedge-shaped ray florets are predominantly yellow but can exhibit shades of orange and red, and they reflex downward (are strongly reflexed). The prominent spherical to dome-shaped central disc is yellow to brownish-yellow. Helenium bigelovii is celebrated for its larger and often showier flower heads, which can measure up to 3 inches (7.5 cm) across. Its ray florets are a bright, clear yellow and are less reflexed, sometimes appearing more open or slightly drooping. The most striking feature is its large, pronounced, and elevated central disc, which is a rich, dark brown or yellowish-brown color, creating a dramatic contrast with the yellow rays.
The flowering period and natural habitat further distinguish these species. True to its epithet "autumnale," H. autumnale blooms in late summer to mid-autumn (typically August to October). It is a plant of moist, low-lying areas, thriving in full sun in ditches, moist meadows, along stream banks, and in prairies. Its native range is vast, covering much of North America east of the Rockies. Helenium bigelovii has a notably earlier bloom time, flowering from late spring into mid-summer (June to August). It is also a moisture-loving plant but is endemic to a much more restricted range, found naturally in wet meadows and seeps at elevation, specifically in parts of California and southern Oregon.
