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Michigan's Invasive Species Community

Hogweed or Not?

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Hi all,

I was recently called out to a site in our CISMA that was ID'd by the caller as giant hogweed. This far into the season, I've really started to sift out what is mis-identified cow parsnip, and what might actually be a valid sighting of hogweed. Getting to the site, I'm having a really difficult time deciding, so I figured I'd post my pictures here for some input. The only in-person viewing I've had of hogweed was at last year's CISMA field trip near Grand Haven, and from my pictures as well as online comparisons I'm still having difficulties! Its not helping the plant is on its way out for the season, so input would be greatly appreciated. Thanks all!

For reference: the plants are topping out at 4' tall, seedheads were 9" across at best. Not sure if hogweed can grow smaller than usually reported? The hairy stems and matching seeds are stumping me.







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WOW This one is close!  But... I'm going with cow parsnip.  Hogweed certainly CAN be shorter than 7 ft, but it's usually pretty darn gigantic, and this just seems "pretty big."  Check out this link for more specific info:

You have some pretty indeterminate seeds, but I'd say overall they seem not-flat and heart-shaped.  Leaves can be tricky, but those just don't seem quite ridiculous-looking enough.  

Interested in other opinions, though!  It's definitely one of the trickiest I've seen.

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I would also agree with cow parsnip. For me the indicators were the color of the stem (not mottled purple), the small size of the leaves, there are less than 50 rays on the primary umbel, the obcordate seed, and that most of the oil tubes on most of the seeds are at around 1/2 the length of the seed rather than >3/4 of the length. 

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