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Environmental Review Toolkit

Invasive Plants Power Point Presentation (view PPT version)

Invasive Plants

What are they and how can we pull together to win the war on weeds!

Invasive Plants vs. Noxious Weeds
  • Introduced from another place minus its competition, and becomes aggressive.
  • EO 13112 gives it legal standing on Federal-aid projects.
  • Harmful to agriculture, human health, and/or environment.
  • Most States have noxious weed law giving them legal standing.
  • 11 DO NOT
  • Some invasives are already on State lists.

My Top Ten Roadside Invasives:

some are on State lists

  • Purple loosestrife
  • Phragmites
  • Leafy spurge
  • Knapweeds
  • Thistles, Canadian, Musk, Scotch
  • Star thistle
  • Kudzu
  • Russian Olive
  • Black locust
  • Ailanthus

Weeds to Watch

Photo of Ailanthus - large, leafy tree along link fence with car in left foreground Photo of Black locust - close-up of white flowers and compound leaves Photo of Knapweed - puffs of purple flowers with abundant wispy greenery
Photo of Kudzu - green leafy vine growing over and covering everything in landscape including tree Photo of Leafy spurge - clusters of small greenish-yellow flowers Photo of Phragmites - tall off-white fronds (large seedheads of very tall field grass) along roadside
Photo of Purple loosestrife - spikes of purple flower-clusters on long stems Photo of Russian Olive - close-up of oval leaves with whitish-green undersides Photo of Star thistle - puffs of yellow flowers on long stems
Photo of Musk thistle - puffs of purple flowers on long stems

Where Do They Come From:

  • PURPOSEFUL introductions
    • Ornamental, esthetics and hardiness
    • Erosion control problem solvers
    • Pasture grasses with forage values
  • ACCIDENTAL introductions
    • Seed in imported crop seeds
    • In ballast of ships
    • Animal vectors . . . . birds and other wildlife
    • Vehicles, travelers, souvenirs, construction

What Can We Do To Prevent Them?

  • Disturb as little as possible
  • Specify weed-free mulches, sods . . .
  • Import NO soils into a project
  • Steam clean gravel at pits
  • Wash down equipment before moving
  • Clean off mowers between sites
  • Train crews to identify weeds early
  • Control before populations spread
  • Control before construction begins
  • Partner with adjacent landowners

And Do Not Plant Them, Please!!!

  • Find alternatives for erosion control
  • Eliminate shrubs and trees known to become problems *
  • Honor adjacent State noxious weed list
  • Plant Native Plants as possible
  • Train personnel to not use in design, revegetation, mitigation plantings

* Educate public at the same time.


Invasive Plants, weeds of the global garden

Randall, John and Janet Marinelli, 1996
Brooklyn Botanic Garden, NY
$9.95 or less on volume order . . . . . .
(What not to plant and why not!!!)

Common Roadside Invasives, a roadside field guide to showy herbaceous weeds in the U.S.

  • Put a copy of this laminated field guide in the glove compartment of every person who works with roadside vegetation management.
  • Not all of these grasses or forbs are in your State at this time. However, invasive plants adapt and move.
  • Be the first in your State to spot and eradicate a new weed invader!!!

Additional References:

  • Greener Roadsides, an FHWA quarterly (Contact Bonnie to add to mailing list.)
  • Land and Water Magazine, Ft. Dodge, IA
  • Ecological Restoration Journal, U of Wis.
  • North American Weed Management Association (
  • National Roadside Vegetation Management Association (
  • Federal Interagency Committee for the Management of Noxious and Exotic Weeds ( or
  • * Roadside Vegetation website:

FHWA's very own Website:

  • Ecological approach to roadsides
  • Chapters of Roadside Use of Native Plants
  • Invasive plant BMPs and more
  • Previous Greener Roadside Newsletters
  • List of State and Division contacts
  • Improved calendar of upcoming events . . . . . .
  • Related websites