Poison Hemlock Popping Up in Princeton

When mathematician and Herrontown Woods volunteer Robert Budny reported that he had found lots of poison hemlock growing in his yard in Princeton, I was at first surprised. I somehow got it in my mind that he was talking about water hemlock--a rarely encountered native wildflower, of which I have come upon a grand total of one growing in Princeton's preserves. 

Robert was quite sure of his find, and said he'd experienced skin irritation while cutting the numerous plants down.

Then I saw this patch of white along Snowden, which too was surprising, since I pass there almost daily yet had never noticed before these tall plants covered in blooms. Maybe it was Robert's sharing of his backyard encounter that primed my eye to take notice.

These, too, proved to be poison hemlock, with broad disks of tiny white flowers. 

and lacy compound leaves. Other plants with white disks of flowers this time of year are the shrubs elderberry and silky dogwood, but they don't have finely dissected leaves like this poison hemlock. 

Though Princeton has many invasive species, those in the carrot family have been few. Goutweed spreads through some gardens. It gets mixed in with the intended plants and can be very hard to eradicate. My neighbor up the street was somehow able to do it, though, through sheer persistence. Wild carrot (Queen Anne's Lace) shows up occasionally along roadsides. It's a beautiful plant, but I've seen it become too much of a good thing in the midwest. Here's information on which members of the carrot family behave invasively in Wisconsin. It includes a useful description of this plant family.

"Many members of the carrot family (Apiaceae) are invasive in Wisconsin. These herbaceous biennials and perennials have alternate, compound leaves with sheaths at the base of leaves. Many small, 5-petaled flowers are arranged in compound umbels (several small umbels combine to make larger umbels). Of the species that are invasive, all have white flowers except wild parsnip, which has yellow flowers. Seeds form in pairs and stems are hollow at maturity."

There are other invasive plant species that, entrenched elsewhere in NJ, are just starting to show up in Princeton. Jetbead and Mile-a-Minute are examples. Catching these early and preventing them from spreading means fewer aggressive plants for gardeners and preserve managers to deal with in the future.

Related posts:

Pulling Jetbead

Mile-a-Minute Spreading into Princeton