Invasive SpeciesGarlic mustard

Alliara petiolata
NOT FOUND by DataTrooper
Cape Elizabeth
ID Confirmed
Quality checked by manyeyes
Peer reviewed by manyeyes
Field Notes
Garlic Mustard Week inspired me to finally document this mystery plant that has plagued my garden for years. I've pulled and pulled and pulled, but it comes back each year. The seed pods and leaves initially looked like garlic mustard to me, but then I looked a bit more closely at the VS species card and started seeing some real differences. So, I'm pleased to report during Garlic Mustard Week that it's not garlic mustard (!), but will continue my tireless efforts to manage its spread here in my yard. I hope someone in the VS community can identify it. "Oh!" you'll say, "I know what that is!" "Thanks," I'll say, "I'll sleep much better tonight knowing what it is." Man, VS is great.
Supporting Evidence
Photo of my evidence.
Teeny tiny flower, four delicate petals, but YELLOW instead of white. It's a nice yellow, I'll give it that.
Photo of my evidence.
Seed pods look a LOT like garlic mustard's seed pods, but these seem a little thicker, and are arranged differently in clumps at the top of each stem.
Photo of my evidence.
Leaves are deeply lobed, but the shape of the leaf isn't as triangular as it would need to be to be garlic mustard. Phew.
Species Observation: Species Looked For
Did you find it?: 
I think I did not find it
Scientific name:
Alliara petiolata
Common name:
Garlic mustard
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.567973 °
W -70.223926 °
Observation Site Information
A photo of our study site.
Upland - Developed areas
Trip Information
Richmond Terrace
Trip date: 
Fri, 2011-07-01 19:31
Town or city: 
Cape Elizabeth
Type of investigation: 
Species Survey


Just had the same problem trying to ID this plant. I strongly suspect it's Chelidonium majus or Greater Celadine. Yellow flower with single green pistil arranged in an umbel. Long seed pods. The similarity with members of the mustard family and brassicaceae led me on a false lead, until I started searching on 'umbel' which none of the brassicaceae apparently have. The plant in our garden is the double form, just to confuse matters.

Wow! I think you did it. You solved my mystery. I'm excited to dig into the resources you sent to learn more. If you know any more about where else it is in Maine or how it got to Maine (assuming it's not from here based on its behavior), I'd be interested to hear.

And I like knowing the term umbel now!

Big cheers for Half Highlander.

No problem. Just a little applied knowledge which included looking at many aspects of the plant. E.g. leaf shape and arrangement on stem, flower colour and arrangement on stem (umbel), the seed pods shape, and any other distinguishing feature. It helped that I had the same plant in my garden which I was trying to ID. Apparently the seeds are dispersed by ants, and the way to stop it spreading is destroy plants before they set seed. Chelidonum Majus is mildly toxic, but has apparently a number of medicinal properties with the sap being used in the past to kill warts (it's noted to be viracidal), also other parts of the plant used to cure toothache, but then I'm just reading what I'm stumbling across on the web. I'll have to dig out some of my old herb books and see if they mention anything. However, considering it's previous medicinal usefulness, I would hazard a guess (a rather VERY unsupported hypothesis at the moment) that it's possible to have been brought over by early to late settlers for this use. Either that or it's come over the same way as other invasive species and accidentally included with something else, eg other types of seed.

Photo: Yellow flower (double form) of Chelidonum Majus showing the single green pistil and beside it a broken stem demonstrating the distinctive bright orange/yellow sap.


GREAT photo of all of the key features! Thanks for sharing the photo and the natural history bits. It makes me like greater celandine a LITTLE bit more than I did before (but I'm still yanking it out as it spreads and spreads and spreads and...).

Thanks for the tips. I checked out Ranunculus repens online. The flowers look similar, but the fruit/seed pods are really different. I'll give a wildflower guide a shot. Thanks for the push I need to try to ID this.

What you have is definitely not garlic mustard, as you observed, but it looks like something from the buttercup family (Ranunculus). You can probably easily identify it with a wildflower guide (like Peterson's or Newcomb's). Good luck! Ranunculus repens is a creeping buttercup that is invasive in New England. I cannot tell from your photos if it is this species, but it may be from your description of its habit.

Keep us posted!