3. Eupatorium fistulosum Barratt (hollow-stemmed Joe-pye weed)
R.M. King & H. Rob.
e–g; Map 1111
60–300 cm long, hollow between the nodes, with a relatively large
central cavity (except sometimes toward the tip), usually glabrous below the
inflorescence, more or less evenly dark purplish-tinged, moderately glaucous,
generally lacking small axillary branches or fascicles of axillary leaves.
Leaves mostly in whorls of 4–7, the uppermost leaves rarely opposite,
the petiole 2–25 mm long. Leaf blades 5–30 cm long,
15–60 mm wide, narrowly to broadly lanceolate or elliptic-lanceolate,
tapered at the base, tapered to a sharply pointed tip, the margins sharply
toothed, the upper surface glabrous or sparsely short-hairy, the undersurface
glabrous to sparsely to moderately short-hairy mostly along the veins, also
glandular, with 1 main vein. Inflorescences terminal panicles, often large,
usually narrowly dome-shaped. Involucre 6.5–9.0 mm long, slender, the
bracts ovate to lanceolate or narrowly oblong-elliptic, rounded or bluntly
pointed at the tip, often 3-nerved, often minutely hairy, often somewhat
purplish-tinged. Disc florets 4–7(–8). Corollas 4.5–7.5
mm long, the surface often somewhat glandular, pale pink or less commonly
somewhat purplish-tinged. Fruits 3.0–4.5 mm long. 2n=20.
in the eastern half of the state and most frequently recorded from the
Mississippi Lowlands Division (eastern Missouri west to Michigan, Missouri, and
Texas; Canada). Bottomland forests, mesic upland forests, swamps, and banks of
streams and rivers; also roadsides.
fistulosum tends to be
the tallest Joe-pye weed in the state, with stems frequently more than 2 m. It also
tends to have narrower main stem leaves than do E. maculatum and E.
purpureum. Collectors sampling only the uppermost portion of the plant have
been fooled by the stems, which frequently are solid rather than hollow toward