About Eupatorium sessilifolium L.
Eupatorium sessilifolium L. is a perennial herb that can sometimes grow over 100 centimeters (40 inches) tall. Stems grow from a woody underground caudex or short rhizome. The upper section of the stem, where branching toward the flower heads begins, is covered in short hairs, while the lower stem is hairless. Its leaves grow in opposite pairs, have toothed margins, rounded bases, and are sessile (lack leaf stalks), but do not clasp around the stem. Glands are dotted across the plant's foliage. This species blooms from August to September, or July in the southern portion of its range. It produces branched small inflorescences made up of widely spaced, tiny white flower heads arranged in flat-topped (corymbiform) clusters. Each flower head typically contains five or six disc florets, and has no ray florets. Eupatorium sessilifolium grows in open woods or woodland edges with well-drained soil, and occurs uncommonly in remaining prairie habitat. It is classified as a threatened species and is legally protected in Michigan. It is also a threatened species in Minnesota, where only a few populations exist in the extreme southeast of the state.
