List A Species in Boulder County
State Weed Law
The
Colorado Noxious Weed Act states that noxious weed management is the
responsibility of each local governing agency -- incorporated
municipalities, counties, and lands owned by state and federal
agencies. The Act states that the board of county commissioners of each
county in the state shall adopt a noxious weed management plan for all
of the unincorporated lands within the county.
The
Boulder County Noxious Weed Management Plan was adopted in January
of 1992. Enforcement of the weed management plan is the responsibility
of the Zoning Administrator under the County Land Use Department. The
County Weed Manager coordinates with the Zoning Administrator for
notification and enforcement of the management plan. Boulder County, in
cooperation with the Natural Resource Conservation Service, Cooperative
Extension, and other agencies, actively recruits landowners to control
all listed weed species, particularly List A species. The County will
enforce on noncompliant landowners.
Of the 18 List A species, only nine are currently
known to exist in Colorado, and seven of those nine are known to exist
in Boulder County. Those species are:
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Myrtle
Spurge/Donkey Tail Spurge (Euphorbia myrsinites)
Myrtle spurge is a
tap-rooted perennial that can
reproduce by seed or plant fragments.
Myrtle spurge is an escaped ornamental, commonly found within most
municipalities in Boulder County.
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Orange Hawkweed (Hieracium aurantiacum)
 Orange hawkweed invades a new area by seed, but vigorous stolon
growth quickly expands the infestation to as many as 3200 plants per
square yard. This plant has recently invaded Colorado and
early detection and eradication is very important to contain this
plant before it becomes a major ecological problem.
Orange hawkweed is difficult to control with handpulling because
of its stout root system.
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Cypress spurge
A perennial, escaped ornamental plant. Cypress spurge is not
known to exist on any County-owned land. Some small infestations
occur on private land.
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 Purple Loosestrife (Lythrum salicaria)
An escaped ornamental plant that has invaded millions of wetland
acres in the United States, purple loosestrife has devastated
habitat for waterfowl and amphibian species. A single mature
plant can produce 2.7 million seeds per plant. Some 'sterile'
varieties of this plant are still sold, but even a plant which is
99.9% sterile will produce hundreds of seeds!
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Dyer's Woad (Isatis tinctoria)
A member of the mustard family, dyer's woad produces bright
yellow flowers grouped in an umbrella-shaped top. Large seed
pods are black when mature. This plant is a serious problem in
Utah, but is not yet common in Colorado.
Dense infestations degrade native plant ecosystems and reduce
forage production.
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 Yellow Starthistle (Centaurea
solstitialis)
A new arrival in Boulder County and Colorado, the yellow
starthistle is actually a type of knapweed which has many sharp
spines. It has taken over more than 8 million acres in California,
and is a serious threat throughout the west.
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Mediterranean sage
A biennial member of the mint family. the mature plant breaks off
at the base and spreads seed by tumbling in the wind. Mediterranean
sage is found primarily in the east central portions of Boulder
County, has been on the County weed list for over ten years, but
still persists as a troublesome weed on public and private lands.
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For more information on controlling any of these weeds, contact the
Boulder County Weed Coordinator at (303) 678-6110 or the
Cooperative
Extension Service at (303) 776-4865.
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Learn to recognize 'Plants of Special Concern' and Noxious
Weeds, and do not plant them in your garden. If they already
grow in your garden, remove them.
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Educate friends and neighbors who have these plants growing on their
properties. Their plants will likely spread to your property.
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Minimize spread of weeds on open space by staying on the trails,
feeding horses weed free hay, and cleaning weed seeds from your hiking
boots or bicycle tires before recreating on open space property.
Back
to Main Weed Division Page
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