"An evaluation of Echinacea angustifolia in experimental rhinovirus infections". ^ Turner RB, Bauer R, Woelkart K, Hulsey TC, Gangemi JD (July 2005).County-level distribution map from the North American Plant Atlas (NAPA). An illustrated flora of the Northern United States, Canada from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102nd meridian. Louis, MO & Harvard University Herbaria, Cambridge, MA. New York and Oxford – via, Missouri Botanical Garden, St. Flora of North America North of Mexico (FNA). In Flora of North America Editorial Committee (ed.). The Global Compositae Checklist (GCC) – via The Plant List. It is a larval host to the silvery checkerspot. The use of Echinacea as a medicinal plant has not been demonstrated to have any positive health effects. The states of Tennessee and Wisconsin list the species as threatened, mostly due to habitat loss and over-collection of roots, which are made into herbal medicine. Most of the known populations are in the region from southern Wisconsin and Iowa south to Louisiana and eastern Texas, with additional reports (many of them likely from introductions) in the Southeastern United States, New England, New York, Michigan, and Ontario. It is found in the Mississippi Valley, the southeastern Great Plains, and the region south of Lake Michigan. The fruits are cypselae and are tan or bi-colored with angled edges. Echinacea pallida blooms from May into July. The flower heads are from 3⁄ 4 to 3 inches (1.9 to 7.6 cm) wide with pale rose-purple or nearly white ray florets. Flower head rays are narrow, linear, elongated, and drooping, ranging from 1 to 3 inches (2.5 to 7.6 cm) long. The leaves are elongated lanceolate or linear-lanceolate with three veins. Stems are green or mottled with purple and green. They have deep taproots that are spindle shaped, wider in the center and narrowing at the ends. Plants normally grow with one unbranched stem in the wild, but often produce multi-stemmed clumps in gardens. angustifolia, but plants often grow taller, ranging from 1.5 to 2.5 ft (45 to 75 cm) tall, with some growing 3 ft (90 cm) or more tall.