Both of the Carrot Family (Apiaceae), it’s no wonder giant hogweed and cow- parsnip are mistaken for one another. Not only do they share similarities in appearance, but they prefer the same growing environments – roadsides, wood edges, ditches, and floodplains. Despite this, cow-parsnip is a native species and serves as a highly important pollen and nectar source for many bees and wasps. Giant hogweed, on the other hand, is highly invasive and easily out-competes nearby vegetation. Additionally, its sap causes chemical burns after the affected area is exposed to sunlight – a major reason for learning proper identification!
Giant Hogweed (Heracleum mantegazzianum)
Introduced as an ornamental in the early twentieth century and native to Asia, it is now prohibited under Michigan law.
Flowers- June and July, small and white, head is 8-20 inches across
Height- Can grow up to 20 feet tall
Leaves- Alternate, coarsely toothed and deeply lobed, divided into 1-3 large leaflets
Cow-parsnip (Heracleum maximum)
While still large compared to many other native plants, it is not nearly as tall as giant hogweed. Coming in contact can also result in photo-sensitivity but to a lesser degree. One must break open the plant to be exposed to the sap, whereas, just brushing up against hogweed can cause rashes.
Flowers- May and June, small and white, head is 2-8 inches across
Height- Can grow up to 9 feet tall
Leaves- Leaves divided into 3-5 coarsely toothed, lobed leaflets
To learn about several other look-a-likes, visit this site!
ISN hosted public workbees in Grand Traverse, Manistee, Benzie and Leelanau Counties. We would like to thank the 44 enthusiastic volunteers who put in over 132 hours of work pulling garlic mustard this month. With their help, ISN pulled more than 5,300 pounds from over 11 acres of high quality habitat. A big thanks to our partners, Oryana for providing a delicious garlic mustard lunch, our lunch host sites, and our volunteers for coming out rain or shine (or snow!) and making a huge dent in the populations of this invasive species at Magoon Creek, Tank Hill, Clay Cliffs, and the Nature Education Reserve at Oleson Bridge. Check out photos from our workbees!
Much of the garlic mustard we collect is shared with Paperworks Studios and turned into paper and greeting cards. Learn more about this exciting partnership as featured on 9&10 News and in the Record Eagle. Shop for garlic mustard greeting cards here!
We are gearing up for Japanese knotweed treatment! Japanese knotweed is a very tricky plant to control, and is a major threat to Michigan’s streams, wetlands, and other high quality habitats.
– Very dense, deciduous shrub, growing anywhere from 2-8 feet tall.
– Flowers from mid April through May.
– Fruits (bright, red berries) are mature from July to October.
– Introduced as an ornamental in late 19th century and still sold in many nurseries and used by landscapers.
Common and Glossy Buckthorn
– Woody shrubs or small trees, forming dense and shady stands.
– Can grow 20-25 ft tall, 10 in. diameter.
– Brown/gray bark. Common buckthorn often has short, spike-like thorns. Glossy buckthorn is thornless.
– Small, dark purple-black berries that ripen in late summer and into fall months.
– Introduced as an ornamental. Some cultivars are still being sold.
– 6-15 feet tall, depending on species.
– Vines can reach 30 feet in length.
– Flowers from May to June. Dark red berries appear in late summer and fall.
– Also introduced as an ornamental.
– Can grown up to 20 feet tall and be upwards of 30 feet wide.
– Round shape with dense branches.
– Bright red fruits appear in September and into October.
– Native to Asia, introduced in 19th century for wildlife cover and food.
– Very little deer browse.
As you can see, these examples of woody invasives share many of the same qualities. They were introduced as ornamentals or wildlife habitat and quickly became out of control, forming dense thickets that crowd out the more desirable native species. Additionally, these species are all very shade tolerant and leaf out very early in the year. They then retain those leaves late into the fall. This makes it even more difficult for natives to flourish – with less sunlight, little access to moisture, and fewer nutrients. The best time to treat the woody invasives mentioned and others in this category is right now! Herbicides are most effective in the fall as long as they are applied no later than a month before the first expected frost. Cut stumps close to the ground and chemically treat the stub of larger plants. For smaller plants, and if you would rather not apply herbicide, hand pulling and digging may also be effective. It is important to remove the entire root system and not shear off any fragments while digging. Any remnants left behind often leads to resprouts the following spring! Regardless, hand pulling and digging often requires annual follow up to ensure continued control. Remember to be careful with invasive plant waste! Seeds can spread easily. Often the best way to dispose of removed plants is by taking them to your local landfill. Additionally, when using herbicide treatment, always follow the label directions closely!
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