Invasive SpeciesEurasian watermilfoil

Myriophyllum spicatum
ID Questioned
Quality checked by pparent
Peer reviewed by
Field Notes
It is 8:50 PM on this dreary Monday night. The sky is a dark, dark navy blue, almost but a shade of black. It is drizzling slightly, but the air is not cold. The space around me is dark, only illuminated by the headlights of my mom’s silver car. We have driven down to one of the beaches in the Limerick section of Lake Arrowhead. I have just come back from a Chorus Concert at my Middle School, and will certainly be staying up to the early morning completing this delayed project. Oh joy. Not willing to get completely soaked by the early summer’s shower, I race through the night toward the dark, cold lake, still and shimmering in the moonlight. My flip-flops smack noisily as they make contact with the damp sand, even though the humming of the car behind me blocks out the other sounds of the night for the most part. Behind me, my mom rushes forward with the camera. We halt by the lake’s edge, and hastily switch the camera to Night Landscape. As my mother rushes toward the shelter of the old silver car, I snap hasty pictures of the lake and the slimy, disgusting plants that litter the shore. With a smile and a shriek at the touch of the grimy plant, I run through the rain, fluffy skirt swaying in the breeze, concert-done hair frizzing with the coming of the rain. I laugh as I swing the car door open and retreat into the comfort of the dry air. Now the darkness and rain is but a mere memory...except for the plant that lies beside me.
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
The plant that I discovered is quite obviously a vibrant shade of green, as you can clearly see. Though it appears even more luminescent a green submerged in water, it is quite colorful out in the dry air as well. Even though many Maine invasive aquatic plant species are of these color variations, it is still a key point in the evidence.
Photo of my evidence.
My discovered plant sample also just happens to have the exact same leaf structure as the Eurasian Water Milfoil. The leaves have an appearance that is similar to feathers, thin and long. There are many 'feathers' on the plant that I have selected, proving a very clear piece of evidence.
Photo of my evidence.
Notice that the plant selected sprouts many small, red-brown branches protruding from its surface. This is a definite sign of the Eurasian Water Milfoil. I am almost certain that this is the plant that I have claimed it to be.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Myriophyllum spicatum
Common name:
Eurasian watermilfoil
Count of individuals: 
3/4 - Completely covered
Vegetative structures (plants)
How big is it?: 
Greater than 10 cm
Is it male or female?: 
Can't tell
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.673261 °
W -70.746610 °
Observation Site Information
A photo of our study site.
Freshwater - In a pond or lake
Trip Information
Lake Arrowhead
Trip date: 
Mon, 2011-06-13 14:36
Town or city: 
Type of investigation: 
Species and Habitat Survey
MIDAS Code: 
Habitat Observations
Species diversity: 
7 different species
Evidence of vectors: 
Dirt road
Water temperature: 
Dissolved oxygen: 



Hey guys there is also Eurasian watermilfoil in limerick in lakearrowhead if any of u guys good get some pics of it in that area

Hi everyone. This is a great discussion. I just want to set the record straight that the invasive milfoil that has infested Lake Arrowhead is variable water-milfoil (Myriophyllum heterophyllum) NOT Eurasian milfoil (Myriophyllum spicatum). There is only one known Eurasian milfoil infestation in the state of Maine, and it is in a small pond in Scarborough. Thanks, everyone, for keeping your eye out for aquatic invaders!


I was interested in looking at your study because my nephew has a camp on Arrowhead. I also live on Thompson Lake where there is milfoil. I was thinking we had Eurasian water-milfoil, but now after hearing the name variable water-milfoil I think that is what we have.


I enjoyed reading your field notes! Yes you absolutely found a milfoil, and indeed an invasive milfoil, but this is not Eurasian water-milfoil (M. spicatum) as you suspected. This is variable water-milfoil (M. heterophyllum). Note how close the whorls of leaves are arranged along the stem. With Eurasian milfoil, the whorls of leaves are generally spaced several cm apart along the stem. Also, if you were to count the pairs of leaflets on several leaves of your plant, you would find that they rarely get above 11 or 12 in number. Eurasian milfoil leaves generally have more than twelve leaflet pairs.

Thanks so much for keeping an eye out for aquatic invaders!

Roberta Hill
Maine Volunteer Lake Monitoring Program

Your field notes are AMAZING...I'd like to read more please! Perhaps your next chapter can be a visit to this site in the daylight. I'm curious, if you so easily picked up an aquatic plant from the shoreline, how much is out there? I wonder what a weed weasel would pick up!

Thank you very much! I will attempt to visit this plant in the daylight as well. It certainly is causing great trouble in our lake! When I go out on our canoe, I look into the shallow water only to see great tendrils of green slime floating just inches below the surface. It is disgusting and must be stopped.

You are absolutely right. Variable water-milfoil is a very serious problem here in Maine. It is the most abundant invasive aquatic plant species in our state, present in 27 of the 33 known infested waterbodies. The infestation in Lake Arrowhead is actually one of the most extensive. The Lake Arrowhead Conservation Council (LACC) has taken on the formidable task of battling this invader, and is making progress. If you are interested in learning more about that effort, here is a link to the LACC website -

Also, you sound like someone who may be interested in getting more involved in the effort to prevent and detect aquatic invaders. If so please visit the VLMP website sometime and check out the various volunteer opportunities. We will be offering two Invasive Plant Patrol workshops in York County this summer and would love to see at one or both! Here is a link to the workshop schedule -

Keep up the great work!

Roberta Hill
Maine Volunteer Lake Monitoring Program

Adding to this incredible drama is that your observation is showing up waaaay off shore in the middle of the Gulf of Maine. Can you please send correct coordinates so we can keep your awesome observation in the database? Save yourself a trip and use this cool online tool.

Put the correct coordinates in the comments and I'll update them. Thanks for being such an awesome scientist, story teller, artist....! And you sing too? Man.

Haha, sorry, here are the correct coordinates!

Much better. Thanks for your quick response.