Characteristics to Identify
Washington's Noxious Aquatic Weeds and Native Look-a-Likes
MILFOIL SPECIES
Myriophyllum
aquaticum (parrotfeather) - Non-native plant
Emergent leaf stalks - very distinctive
bright green foliage looks like tiny fir trees on the waters surface
Usually 5-8 leaves per whorl (arranged around the stem)
Myriophyllum
spicatum (Eurasian watermilfoil) - Non-native plant
Mature leaves with 14-24 leaflet
pairs, at about a 45 degree angle to the length of the leaf
No winter buds produced
Floral bracts smaller than the flower
The following two native species are
very similar in appearance to Eurasian watermilfoil:
Myriophyllum sibericum (northern
milfoil) - Native plant look alike
Mature leaves with 4-14 leaflet pairs from a 45 degree angle to almost
perpendicular to the leaf length
Cylindrical winter buds
Flower bracts smaller than the
flower
Myriophyllum verticillatum
(western milfoil) - Native plant look alike
Mature leaves with 9-17 leaflet
pairs
Pinnate floral bracts, larger than the flower
Club-shaped winter buds
OXYGEN WEEDS OR WATERWEEDS
Egeria
densa (Brazilian
elodea) - Non-native plant
4 leaves per whorl, to 4 cm
long
Minute serrations along the leaf edges, but you need
magnification to see the serrations
Male flowers only, up to 2 cm across
No tubers
Hydrilla
verticillata (hydrilla) - Non-native plant
5 leaves per whorl - less early in the
season, 1-2 cm long
Visibly toothed leaf edges
Tiny flowers
Tuber present
Similar Appearing Native Species:
Elodea spp. (American waterweed) - Native plant look alike
3 leaves per whorl, usually less than 2 cm
long
Need magnification to see the serrated leaf edges
Tiny flowers
No tubers
FANWORT
Cabomba
carolineana (fanwort)
- Non-native plant
Opposite fan-shaped leaves on long stalks
Small floating leaves are present when growing to the water surface
Similar Appearing Native Species:
Ranunculus aquatilis (water
buttercup) - Native plant look alike
Fan-shaped alternate leaves
Megalodonta beckii (marsh
marigold) - Native plant look alike
Fan-shaped opposite leaves, but the leaf stalks are so short that the
leaves appear whorled.
BLADDERWORTS
Utricularia
inflata (swollen bladderwort) - Non-native plant
Radiating wheel-like float supports the
flower stalk
Small coiled winter buds
Similar Appearing Native species:
Utricularia
vulgaris (common bladderwort) - Native plant look alike
No float on the flower stalk
Large ball-shaped winter buds
When neither structure is present, these two species are extremely
difficult to distinguish
LOOSESTRIFES
Lythrum
salicaria (purple
loosestrife) - Non-native plant
Pink/purple flowers with 6 sepals, 6 petals,
12 stamins
Fruit -a 2 valved capsule
Generally opposite leaves
Square stem
Reproduces by seeds and adventitious buds on buried stems (growth
stimulated by disturbance)
Lysimachia
vulgaris (garden loosestrife) - Non-native plant
Leaves opposite or whorled
Leaves soft-hairy, dotted with black or orange glands
Flowers showy and yellow, 5 petals, fruit is a dry capsule
WILLOW HERBS
Epilobium
hirsutum (hairy willow-herb) - Non-native plant
Showy pink-red flowers with 4 sepals, 4
notched petals, 8 stamens
Round stem
Long seed capsules that split open and release the fuzzy coated seeds
Leaves are opposite and hairy, toothed
GRASSES
Phalaris
arundinacia (reed canarygrass) - Likely exotic ecotype
To 6 feet tall, stem 0.5 inches wide
Leaves 0.25 to 0.75 inches wide
Phragmites austalis (common
reed) - Likely exotic ecotype
To 12 feet tall
Sheath of the leaf blade is smooth and loose allowing leaves to twist
in the wind
Flower spikes feathery
OTHER
Nymphoides
peltata (yellow floating heart) - Non-native plant
4-6 inches across waterlily-like floating
leaves with a slit
Yellow flowers with 5 fringed petals, held above the water's surface
Ludwigia
hexapetala (water primrose)
Yellow flowers with 5 sepals and 5 petals
Alternate leaves
Erect stems
Plant
Identification Table of Contents
| Return
to Aquatic Plants and Lakes
|