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  • Writer's picturemariagross

European naiad with important distinctions

Updated: Jul 25, 2020

July 24

Per my request, Cliff Cabral has now given us the chance to see 4 invasive specimens he is currently harvesting. Three from neighboring waterbodies in Maine and one from NH. Don and I have divided the lot. Each one of you can hold, investigate, and study these invasive plants. Either call one of us or before we go for any trainings with you we can bring the specimens.

Photos of 3 of these specimens have been posted earlier (remember to click on the top description of any invasive to see any additional info and photos:

· Invasive Milfoil,

· Curly Leaf Pondweed

· Hybrid of Invasive + Native Milfoil.

A few days ago Cliff gave me a sample of a 4th invasive:

· European Naiad aka Najas Minor found in Three Ponds in Milton, NH.

What surprised me immediately is that the E. naiad did not look very different to my untrained eye from the native water naiad that we can find in Conway Lake (primarily Najas flexilis.)

European naiad(Rt) with 2 Najas Flexilis (LT) on either side of the dime

I sent this photo to Amy. On the right is the invasive European naiad and both plants between the dimes are native water naiads (Najas flexilis) found in Paige Brook last week. The color variation is normal.

I asked Amy if she could tell from the height of a watercraft whether any visible clump of naiads below could be readily identified as E. naiad. The answer is NO — It is hard to tell, you need plants in hand.  When I do boat surveys I use a rake to get plants in hand.  Diving is best.

I asked her if E. naiad, as an invasive, would grow in such a way that we would see thicker and longer stems than the native naiads. Her answer was NO — Not necessarily. Height varies among lakes, for both native naiads and E. naiad. It can be tricky to go by that.”

Just to complicate all of that a little bit more (!) below is a photo of the E.naiad + N. flexilis + a pondweed that I found right off of my dock. In my reading I found it was important to realize how the common pondweed can initially look similar to both N. flexilis and E. naiad.

Pondweed (Rt) + N.flexilis (Center) and E.naiad (Lt)

Please DO NOT think that the naiad-looking plant below you can be casually identified. Be ready to stop and investigate what you have found. Be sure to use some sort of magnification to study the leaf structures. The barbed appearance of the E. naiad’s leaves is quite easy to see with your eye training on it. It can certainly be confirmed with magnification.

Photo is of one inch pieces of leaf from N.flexilis (Lt) and E. naiad (Rt) taken with a cell phone photo, magnified. Understand that the naked eye can see the E.naiad's barbs at close scrutiny.

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Invasive Species in New Hampshire

Conway Lake is currently free of invasive (aka "exotic") species. The posts below include descriptions of invasive plants and animals we need to watch for when we patrol on Conway Lake. New Hampshire


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