Maine Field Guide to Invasive Aquatic Plants - Brant Lake Milfoil ...

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S u b m e r s e d P l a n t s w i t h S m a l l ( < 5 c m )
U n d i v i d e d L e a v e s A r r a n g e d A l o n g S t e m s
B A C K G R O U N D
1. Leaves are arranged along the stem in strict whorls.
a. Lance-shaped leaves; consistently 3 leaves per
whorl. (See waterweeds, page 50)
b. Generally more than three lance shaped leaves
per whorl. (See Brazilian waterweed, page 36,
hydrilla, page 44, and mare's tail, page 54)
c. Whorls of thin, needle-like "leaves.” “Leaves” may
appear barbed. (See stoneworts, page 104 )
2. Leaves are strictly arranged in opposite pairs along the
stem. (See water starworts, page 52)
3. Leaves are alternately arranged. (See pondweeds,
page 96)
4. Slender leaves occur in a mixed arrangement. (including
opposite, whorls, and clusters)
a. Leaves are finely but conspicuously serrated.
Serrations are easily seen with a hand lens. (See
European naiad, page 42)
b. Leaves appear to be entire. Serrations are not
easily seen, even with a hand lens. (See native
naiads, page 100)
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