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Key identifying traits
Spreading dogbane (Sd) grows from ½’-2 ½’ tall; Hemp dogbane (Hd)
grows much taller-up to 6’
Both plants are much-branched (Hd has opposite branching) and have
smooth, often red, stems
1-3" long, hairless, oblong lance-shaped leaves are arranged
opposite or in whorls on short stalks
Flowers of both are formed in clusters at the end of stems and in
upper leaf axils; Sd flowers are small, pink, bell-shaped &
fragrant; Hd flowers are small, greenish-white & tube-shaped
Fruits of both are very long, 2"-6", narrow, cylindrical
pods containing many seeds tipped with tufts of cottony hairs
Both have white, milky sap
Biology and ecology
Rhizomatous perennials, reproducing by seed & roots
Both are native to North America
They prefer well-drained soils and are found along roadsides, forest
openings and open hillsides
Both are toxic to livestock (and humans), although browsing is rare
because they are bitter
Hd was widely used by early peoples as a source of strong fiber for
ropes, nets, baskets, etc.
Control
Prevention – Learn to
identify plants; know your property; do not transplant from a roadsides
or forest
Biological – No known introduced biological control; because
they are native, they do have natural enemies
Cultural – Healthy crops and perennial grasses/forbs can help
keep plants from invading and establishing
Mechanical – Very difficult once established due to the
spreading root system; repeated, persistent cutting or tilling can wear
out root reserves
Chemical –
The
PNW Weed Management Handbook does not have this weed listed for
control recommendations |
Spreading dogbane flowers
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