Eupatorium hyssopifolium
Eupatorium cannabinum
hyssop-leaf boneset, hyssop-leaf thoroughwort
hemp agrimony, thoroughwort
(from short caudices or rhizomes) single, sparsely branched distally, pubescent throughout.
(from short rhizomes) single, branched distally, puberulent.
usually opposite or whorled (distal sometimes alternate, spreading or horizontal); simple, sessile;
blades 3-nerved from bases (laterals sometimes weak), lance-linear, lance-oblong, or linear, 20–60 × 2–15 mm (lengths mostly 6–40 times widths), bases cuneate, margins entire, laciniate-serrate, or serrate, apices acute, faces scabrous (at least abaxial).
opposite;
subsessile or petiolate;
blades palmately 3(–5)-lobed (at least larger proximal, lobes relatively broad), blades (or lobes) lanceolate to lance-ovate, 50–100 × 20–40 mm, margins serrate, apices rounded to acute, faces puberulent, gland-dotted.
5;
corollas 3–3.5 mm.
(4–)5(–6);
corollas (usually pinkish) 2–2.5 mm.
8–10 in 2–3 series, elliptic to oblong, 1.5–5 × 1–1.5 mm, apices obtuse to acute (not mucronate), abaxial faces pubescent throughout (more densely distally).
8–10 in 2–3 series, oblong, 4.5–6 × 1.5–2 mm, apices rounded, abaxial faces puberulent, gland-dotted.
in corymbiform arrays.
in dense, corymbiform arrays.
2–3 mm;
pappi of 20–30 bristles 3.5–4 mm.
2–3 mm;
pappi of 20–30 bristles 3–5 mm.
= 20.
Eupatorium hyssopifolium
Eupatorium cannabinum
Varieties 2 (2 in the flora).
Eupatorium hyssopifolium includes both diploid and polyploid cytotypes and presents a complex situation taxonomically. The diploids are placed here in var. hyssopifolium, which also includes polyploids and is characterized by relatively narrow leaves. Variety laciniatum has broader leaves and molecular data suggest that it arose through hybridization between var. hyssopifolium and E. serotinum; the name E. torreyanum has been applied to plants of similar morphology, but these are hybrid derivatives of E. serotinum and E. mohrii. It has also been suggested that var. hyssopifolium has hybridized with E. album var. album to form E. saltuense, and with diploids of E. linearifolium to form polyploid populations included here under E. linearifolium. Eupatorium hyssopifolium is characterized by a tendency for the leaves to be whorled, in 3s and 4s, and for axillary buds to produce leaves without expansion of shoots; the combination of whorled leaves and suppressed axillary shoots gives the nodes a somewhat tufted or verticillate appearance.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Eupatorium cannabinum is a garden escape; it is native to Europe and may be established in British Columbia; it is only casually adventive elsewhere in the flora area.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaves mostly linear, 2–5 mm wide, margins usually entire or obscurely serrulate | var. hyssopifolium |
1. Leaves mostly lance-linear to lanceolate, 5–15 mm wide, margins usually laciniately toothed | var. laciniatum |
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