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Click on the titles below to learn more about CRISP's invasive terrestrial plants!


warning_sign.gif Giant Hogweed

(Heracleum mantegazzianum)

This terrestrial plant can reach heights of 15 feet. It is considered a noxious weed and coming into contact with it can cause some serious health effects. Giant hogweed's sap causes phytophotodermatitis (hypersensitivity to ultraviolet light) which can result in scars, blisters, and even blindness. Even though you may think this flowering plant looks pretty, it is a public health hazard. If you come into contact with this plant, seek medical attention! Report any giant hogweed sightings so a team can be sent to remove the dangerous plants for you! Crews can perform both chemical management and effective manual control to kill giant hogweed.

View CRISP's Giant Hogweed Management Plan

Check out our video on Giant Hogweed!


berries_and_leaves.jpg warning_sign.gif Mile-a-Minute Vine 

(Persicaria perfoliata)

There are now three infestations of this plant in the CRISP region.  Please report if you see this plant here  Keep an eye out for its perfectly equalateral triangular leaves, downward pointing barbs, ocrea (round leaves that surround the stem to make little disks), and clusters of blue berries.  In the right conditions, this plant can grow up to 6 inches in a day! If it isn't controlled, mile-a-minute will create a thick mat that shades out native plants and eventually can form impentrable thickets. To control Mile-a-Minute, pull plants up by the roots beginning in mid-summer and continue to pull new germinants through the fall. Carefully remove and bag all berries and allow to rot in sunny location for several weeks, then dispose of in trash. Do not compost.

Check out our video on Mile-A-Minute!



Asiatic Bittersweet

(Celastrus orbiculatus)

This woody vine was initially brought from east Asia and planted as an ornamental. It grows vigorously and smothers native vegetation, blocking them from sunlight.  This invader looks very similar to our native American bittersweet (Celastrus scandens), which we want around! Be sure to learn the differences between American and Asiatic bittersweet before you perform any control as the two are very similar. Consistently cutting vines and pulling up root shoots several times a year for several consecutive years will eventually weaken plants. Alternatively, careful application of glyphosate on cut stems can be done in the fall.

 Watch our video on Asiatic Bittersweet!



Norway Maple

(Acer platanoides)

Though it is widely sold as an ornamental and looks similar to our native maples, this tree is decreasing plant diversity in the region's forests.  Norway maple's shallow root system competes with surrounding vegetation and the dense shade generated by full-grown Norway maples prevents sunlight from reaching native understory species. Pull up seedlings and saplings!

Watch our video on Norway Maple!




Pale Swallow-wort

(Cynanchum rossicum)

This perennial twining vine is a member of the milkweed family. Pale swallow-wort grows rapidly, choking out native vegetation as it becomes established. Though its star-shaped flowers are attractive, this is not a species we want in the Catskills-- swallow-wort can alter grassland succession and make certain ecosystems uninhabitable by desired native species. To manage this species, consistently mow or cut its stems- don't pull it up! Disturbing the roots can actually help make more plants.

Check out our video on Pale Swallow-wort!