Wildflowers of the United States

Wild Quinine, American Fever-few - Parthenium integrifolium

Genus Common Name: Feverfew

Native Status: Native

Dicot Perennial Herb Leaves:Alternate

Parthenium integrifolium - Wild Quinine, American Fever-few.
Parthenium is a relatively small genus of Asteraceae with about 16 species worldwide and 7 or 8 in the United States. The genus scientific name Parthenium is Greek for virgin, indicative of the white flowers. The genus common name Feverfew is indicative of its use medicinally, as is the common name of Parthenium integrifolium - Wild Quinine, which has been used in treatment for malaria.

Parthenium integrifolium is the most widespread (or maybe only native) of the eastern Feverfew species, being found in 27 states from Texas and Oklahoma north to Minnesota and east to Massachusetts. It is not a deep south species, being found only in the northern part of the southern tier of states; absent from Florida entirely.

Other than the introduced annual Parthenium hysterophorus (identified by pinnatifid or bipinnatifid leaves with the sinus extending almost to the midrib of the leaf), the perennial Parthenium integrifolium may be the only eastern Feverfew species, depending on how you classify the genus. Many authorities, including Weakley, consider Parthenium auriculatum - Glade Wild Quinine - found in 6 or 7 southeastern states - to be a separate species, but some (including ITIS and FNA) consider it to be a variety of Parthenium integrifolium. Weakley classifies Mabry's Wild Quinine as Parthenium integrifolium var. mabryanum, while ITIS and FNA do not consider it to be a separately recognized variety. There does seem to be relative consensus now, however, to consider Parthenium radfordii as part of Parthenium integrifolium, although those that accept var. mabryanum place it within that variety, while as previously mentioned, some do not accept that varietal level at all.

Found in:
AL, AR, CT, GA, IA, IL, IN, KS, KY, LA, MA, MD, MI, MN, MO, MS, NC, NY, OH, OK, PA, SC, TN, TX, VA, WI, WV, GS

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Distribution of Parthenium integrifolium in the United States and Canada:

Map courtesy of The Biota of North America Program.
Map color key
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Site: May Prairie State Natural Area, Coffee County, TN Date: 2016-June-01	Photographer: Gerald C. Williamson Nikon D7000 Tamron SP 90MM f/2.8 AF Macro
The inflorescence of Parthenium integrifolium is what I think would be described as a somewhat flat-topped corymbiform panicle. The heads are held in several-branched clusters usually with the outermost heads blooming first. These inflorescences terminate the branches, both the main and those arising from the leaf axils. The individual flower heads are off-white and usually have 5 but sometimes 6 tiny ray florets surrounding 15 or more disc florets. The plant grows to about 3 feet tall.

Site: May Prairie State Natural Area, Coffee County, TN Date: 2016-June-01	Photographer: Gerald C Williamson Nikon D7000
The leaves of Parthenium integrifolium are variable - leading to the disagreement over which plants are different species, different varieties, or just forms. The leaves are usually serrate (as here) or crenate, but may be pinnately lobed in var. mabryanum. The basal rosette of leaves are on petioles, but the cauline leaves may or may not be petiolate. If petiolate, the petioles may be winged. The base of the cauline leaves may be auriculate clasping, as shown in this photo, but "only rarely" if you subscribe to separating P. auriculatum from P. integrifolium, in which case that species separation is contingent on habitat and characteristics of stem hairs - P. auriculatum with coarse, spreading hairs up to 3 mm long, and P. integrifolium glabrous or with appressed hairs under 1 mm long. The plant here does not have spreading hairs on the stem, indicating P. integrifolium.
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References used for identification and information:

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Parthenium integrifolium initially published on USWildflowers.com 2018-06-04; Updated 2018-06-04

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All content except USDA Plants Database map Copyright Gerald C. Williamson 2024
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Code Update 20230302