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transcript
Final Paper: Pacific Northwest Invasive Species
Nymphaea odorata, fragrant water Lily, tuberous water lily, white water lily
Allison Northey
Autumn 2014 FISH 423: Olden
12/5/14
Figure 1: photo on left shows the flower of N. odorata. Photo on the right shows eradication efforts of
the aquatic plant in a residential lake. Photo credit:
https://www.google.com/search?q=fragrant+water+lily
Taxonomy
Order: Nymphaeales
Family: Nymphaeaceae
Genus: Nymphaea
Species: odorata
Identification Key
Nymphaea odorata, under the more
common names of the fragrant water lily, sweet-
scented water lily, or white water lily, is a
perennial flowering aquatic plant found in
freshwater environments. It is a floating leaved
and rooted plant, thriving in about three to six
feet of ponds and lakes. The plant arises from
dense fleshy rhizomes (King County, 2010). A
rhizome is a starch-storing root organ that grows
horizontally. They are located beneath the
surface of the soil, and range from 2-3 cm in
diameter (Dept. of Ecology Water Program,
2005). The root system is impressive; one
planted rhizome can cover a massive amount of
space, increasing surface area of the roots.
Surface area is important in this circumstance
for greater uptake of nutrients through the root
system. Rhizomes branch out and each new
portion can produce a root and shoot system of
its own (Seago et al., 2000). N. odorata grows
with only its leaves and flowers exposed to the
air, while the rhizomes are anchored in the
bottom of the body of water and remain
inundated (Seago et al., 2000).
Its many-petaled flowers (can be 25 or more
petals per flower) grow in a range of white to
pink with yellow centers. The petals are roughly
¾-4 inches long, thick and pointed at the tip
(Wildflower Center, 2010). These petals are
larger on the outside and smaller toward the
inside of the flower. Flowering occurs three days
at a time from about June to October each year.
These flowers are fragrant, hence the common
name, and emit a sweet honeysuckle-like odor,
which is equally intense during all three days of
flowering (Schneider and Chaney, 1981). There
can be between 72-107 stamens, which come in
two forms with the differences being in the
length of the filaments (Schneider and Chaney,
1981). A stigmatic cup is present, which holds
stigmatic fluid, which attracts pollinators to the
flower (Schneider and Chaney, 1981).
N. odorata has bright green leathery leaves with
a purplish lower surface that can grow up to ten
inches in width. The leaves have a waxy outer
layering called the cuticle, which protects the
plant from pathogens. The leaves are narrow and
deeply cut just about the center, where the stem
is attached (Wildflower Center, 2010). The
flexible leaf stem also arises from the rhizome.
Both the leaves and the flowers usually float on
the surface of the water, especially when water
levels are lower. A multi-celled fruit is also
developed, and the stalk of the fruit bends
downward so the fruit matures underwater.
(Hilty and Hogan., 2002)
There are only a few species similar to the
fragrant water lily. N. odorata can be easily
confused with Spatterdock, or Nuphar
Figure 2: N. odorata leaf, top and bottom. Photo credit:
http://www.illinoiswildflowers.info/wetland/plants/fr_w
aterlily.htm
polysepala, which can also be found in
Washington lakes and ponds. However, once
blooming, they can be easily distinguished due
to differences in flowers- the fragrant water lily
having much more ‘showy’ flowers than the
spatterdock (Dept. of Ecology, 2014). Another
similar species, the native dwarf water lily
(Nymphaea tetragona) has flowers that are not
fragrant, and only have about ten petals per
flower (Dept. of Ecology, 2014).
Life Cycle/Feeding Habits
The life cycle begins with a seedling
sprouting from a seed. The roots burrow into the
soil and gain nutrients for the plant to grow. The
entire life of a single water lily plant will take
place in exactly the same location due to the
roots being lodged in the substrate. However,
propagation of the lily can establish plants
elsewhere due to water currents or other
dispersal mechanisms. Photosynthesis occurs
due to the clear water, and the leaves begin to
grow toward the surface of the water. The plant
will produce flowers, forming the reproductive
organs of the plant. The blooming period of N.
odorata is during the summer and early fall
(Hilty and Hogan., 2002). There are not many
novel-feeding habits of the plant, though many
nutrients are essential to the growth of the plant.
Nitrogen-fixing bacteria aid the plant in taking
in atmospheric nitrogen in the form of N2 and
fixing it into ammonia for the plant to use.
Other substances need for growth or ‘feeding’
are CO2 and sunlight.
Reproductive Strategies
Each flower of the fragrant water lily
has both male and female reproductive parts.
This allows the plant to reproduce asexually, and
also with the aid of propagation of the rhizomes.
The plant also reproduces sexually. When
flowering, each flower lasts only three to four
days; opening in the morning and closing in the
afternoon (Hilty and Hogan 2002). Fertilization
processes occur first, then pollen is released
from the flowers second. On the first day, the
flowers produce a liquid in the center of the
flower (in the stigmatic bowl) that attracts
pollinators and are receptive to pollen from other
flowers (Schneider and Chaney, 1981). Pollen-
covered insects are attracted to the sweet smell
and fall into the liquid, washing the pollen of
their bodies and therefore fertilizing the female
parts of the flower, the stigma (Schneider and
Chaney., 1981). Insects may actually drown in
the liquid if they continuously slip back into the
cup (Schenider et al, 1981). On the second and
third days, the liquid is no longer produced, but
pollen is produced on the stamens. Insects pick
up this pollen, which is then transported to other
flowers. Then, the coiling of their stalks brings
the fruits (produced one week after pollination)
underwater (Schneider and Chaney., 1981). The
fruits take roughly three to five weeks to mature,
and break open when the seeds are to be released
(Richards and Cao 2012). The seeds within the
fruit will subsequently give rise to new N.
odorata plants.
Environmental conditions
Optimum growing conditions of the
fragrant water lily include high water
availability, (because most of the plant is
submerged) but in mostly shallow water. The
water should be slow moving with very slight to
no contact with high winds or waves. N. odorata
grows best in water that is between 15-18 oC,
and germinates most efficiently in 13 oC (Else
Figure 3: N. odorata many-petaled flower, the
reproductive organ. Photo credit:
http://www.minnesotawildflowers.info/udata/r9ndp23q/
white/american-white-waterlily_0624_131045.jpg
and Riemer 1984). The seeds also have been
founf to germinate at a maximum depth of about
90 cm (Else and Riemer 1984).
The rhizome root complex of the plant prefers
soft sediment substrates so it can easily lodge
and secure itself (Seago et al, 2000). The water
lily is flexible in that it can grow just fine in
direct sun, part shade, or shade, and is both cold
and heat tolerant (Wildflower Center, 2010). N.
odorata is able to thrive in conditions where the
water is as low as 6” deep or as high as 7’ deep,
and can tolerate a wide range of pH, (Wiersema
1997).
N. odorata can endure many environmental
conditions due to altered structural features
evolved over time. N. odorata has a much
thicker cuticle on the lamina and more layers of
parenchyma cells than most aquatic plants
(Etnier and Villani 2007). More layers of cells
permit the plant to change their mechanical
properties, allowing them to withstand diverse
environmental conditions.
The pollen in the flowers of this water lily
attracts specialist visitors, many of which are
bees. Hylaeus nelumbonis and Lasioglossum
nymphaearum in particular are the main
specialist visitors (Hilty and Hogan., 2002). The
organs of N. odorata are a food source for
insects, moths, ducks, turtles, and beavers. These
include larvae of moths like Monroessa
gyralis (Pyralid Moth sp.), and Synclita
obliteralis (Water Lily Leafcutter).
Several Donacia spp. (Water Lily Leaf Beetles)
feed on water lilies; the adults feed on either the
pollen or the leaves. (Schneider and Chaney
1981). The foliage and rootstocks are sources of
food for beavers. It has no known pathogens or
commensalism relationships with other species.
Geographic Distribution
The native range of the fragrant water
lily is impressive. This list includes the places in
the Bahamas Canada, Cuba, El Salvador,
Honduras, Mexico, Nicaragua, Puerto Rico, and
east and central North America (Specimen Data-
Consortium of PNW Herbaria, 2014). Now, the
fragrant water lily can be found in the following
states; AK, CA, CO, DE, FL, GA, ID, IL, IN,
IA, KA, KY, LA, MA, MI, MN, NY, ME, NV,
MS, SC, SD, RI,
OH, NC, TN, UT,
WV, WI, VT, VA,
OR and WA.
A series of surveys
conducted by the
Washington
Department of
Ecology showed
the existence of N.
odorata at different
survey locations
across Washington
State in 2009-2012.
This invasive
aquatic species can
now be found in
many Washington
state counties,
including; Stevens,
Okanogan, Whatcom,
Skagit, King, Pierce,
Thurston, Skamia,
Figure 4: shows the distribution of N. odorata across the state of Washington among
many survey locations. Photo credit:
http://www.nwcb.wa.gov/siteFiles/WF_Nymphaea_odorata_June_2013.pdf
and Clallam (see figure 4). In developed areas of
King County from 1996-2012, 155 out of 534
surveyed lakes were found to have fragrant
water lily present (NWCB, 2013). It can now be
found in many parts of the world. Figure 5
shows the distribution of N. odorata across the
United States, which has the highest
concentration of N. odorata in the world, despite
some of its native range being in other countries
(Cook, 1990).
The fragrant water lily can live in a range of
conditions, so the estimated geographic range of
the aquatic plant is quite large. Any place with
shallow ponds, lakes, ditches, slow streams, and
swamps is a prime location for a fragrant water
lily plant to invade (Dept. of Ecology, 2005).
N. odorata is labeled as a class C noxious weed
(“C Noxious Weeds”, 2010). In order to be
classified as a class C noxious, weed in
Washington, the weeds are either already
widespread or are of use in the agricultural
industry. A county is able to enforce control if
necessary, and aid in removal or control can be
called upon to eradicate (“C Noxious Weeds”,
2010).
It has been speculated that the fragrant water lily
was first introduced into Seattle, Washington
during the Alaska Pacific Yukon Exposition in
the late 1800’s (NWCB, 2013). According to the
Pacific Northwest Herbaria database, the first
actual record of N. odorata in Washington is
from 1911 (Specimen Data- Consortium of
PNW Herbaria, 2014). Historically, N. odorata
has been seen to repeatedly invade areas where
dams have been constructed, either by humans
or beavers. (Hilty and Hogan 2002).
Figure 5: United States distribution of N. odorata Photo credit:
http://www.minnesotawildflowers.info/flower/american-white-water-lily
Invasion Process
Introduction
The chief pathway of the fragrant water
lily is via the horticulture trade, with the vector
being shipping. Deliberate planting by humans is
unfortunately the primary source of introduction
into new bodies of water (NWCB, 2013). The
fragrant water lily is directly transplanted by
humans for decorative purposes, and sold
commercially via the aquarium and horticulture
trades (Briggs, 2006). Many ornamental ponds
on golf courses or other garden areas have N.
odorata placed in the ponds because the showy
flowers are well sought after. At
LiveAquaria.com, anyone can buy a bare
rhizome root of N. odorata for $24.99. The
approximate purchase size is 8” to 16”.
The aquarium trade has been documented to
make mistakes in regards to shipping invasive
species. The magnitude of this problem was
illustrated in a study about the movement of
invasive plants into the state of Minnesota
through the horticulture trade (Maki and
Galatowitsch 2003). Forty aquaculture orders
were placed to a variety of plant vendors across
the United States. Results showed that 18% of
the orders carried misidentified plants, 43% had
unordered seeds, and 93% contained an
unordered species (Maki Galatowitsch 2003). Of
the 93% unordered species in the orders, 10%
enclosed federal noxious weeds or Minnesota
exotic species (Maki Galatowitsch 2003). The
transport of prohibited species is a huge risk
associated with the aquatic plant trade, and it is
highly possible for N. odorata to be introduced
this way. The unintentional contamination of
shipping orders with N. odorata is also a
probable cause of introduction through
horticulture trade as well.
As we have discussed in class, it is possible that
once an owner of N. odorata no longer wishes to
keep the plant, they may dispose of the plant
incorrectly, perhaps by dumping it into a nearly
pond. This is yet another introduction route
however unintentional it is, of this aquatic plant
into novel areas. . Also, with the long stems of
the water lily, it can easily be wrapped up on the
motors of recreational boats and introduced by
that vector (Olden, 2014).
Establishment
Once introduced to a novel area, there
are many reasons why the water lily establishes.
The water lily is a hearty plant, despite its gentle
appearance. The characteristics of the plant are
very ‘plastic’ (being able to live in various
habitat conditions) allows for probable
establishment in a novel area. (Briggs, 2006). If
a rhizome root is broken up, the fragments will
float to new areas and can create new patches of
plants (NWCB, 2013). This results in high
propagule pressure; as more rhizomes break up,
More N. odorata plants are spread and
established in an environment. It is widely
known that as more numbers of individuals are
released into an environment, the larger chance
of establishment the said species has. N. odorata
has clever fertilization tactics. Absorbing the
pollen via liquid in the flower is a rather foul-
proof way of fertilization. The sheer number of
seeds released into the water by the plant also
allows again for high propagule pressure.
Spread
Once the fragrant water lily has been
established in a novel environment, it has the
ability to proliferate rapidly. The seeds mature
underwater and can sink to the bottom and
germinate in a vegetative colony, or can be taken
by a current to distribute to novel areas.
Waterfowls, turtles and ducks consume the fruit
and also spread the seeds to new locations
(Schneider and Chaney. 1981).
According to a study done by Mary Jane Else
and colleagues (see figure 6), N. odorata seeds
tend to germinate in higher percentages when
large numbers of seeds were crowded into a
small container (Else and Riemer 1984). This
phenomenon is due to the presence of an
ethylene gas, which is only released when seeds
are crowded together, and triggers simultaneous
germination of the seeds (Else and Riemer
1984). This is essential for the spread of N.
odorata, because as more plants germinate,
more plants subsequently spread to new areas.
Note that this study can also be related to the
establishment of the water lily, depending on
what stages of invasion the water lily is in at the
time of germination.
Recall the rhizome root system of N. odorata.
Rhizomes can spread extremely quickly once
being established. A single planted rhizome will
cover upwards of a 15-foot diameter over the
course of five years (Seago et al, 2000). Records
were kept of the spread of N. odorata in Giffin
Lake, a 110-acre lake in eastern Washington. In
1974, open water is documented, and roughly
11-25 percent of the lake was immersed in
various unknown aquatic plant species. No
management strategies were put in place, and
within 20 years later the lake saw a drastic
change. Nearly 100 percent of the surface of the
lake was covered with N. odorata, most likely
due to the spreading ability of the rhizome root
(Thurston County Lakes Program, 2014). This
not only shows the competition ability, but the
extraordinary rate of spread of the plant. This
also demonstrates the dire need for immediate
action when it comes to controlling invasive
aquatic plants such as N. odorata.
Impacts
Fragrant water lilies can
have negative impacts that can
affect both humans and other
aquatic species. According to the
Washington State Department of
Ecology, the fragrant water lily is
second to Eurasian water milfoil in
regards to nuisance (Washington
Dept. of Ecology Water Program
2005). As far as the effect on other
species, N. odorata can have
consequences on different levels of
impact including population,
community, and ecosystem, also
serving as an ecosystem engineer.
An ecosystem engineer means a
species can destroy or modify the
physical habitat (Olden, 2014). N.
odorata has been documented to blanket the
surface of water with its tendency to grow in
high densities (Else and Riemer 1984). Growing
in high densities results in the crowding out of
native plant species, as well as less sunlight
penetrating the water. Sunlight is absorbed in the
dense leaf mats, increasing the water
temperature, which can have adverse affects on
the ecosystem. Less sunlight means
photosynthesis is weakened or even stopped in
submerged aquatic plants. (Cook, 1990). It is
very difficult to conduct rigorous ecosystem-
level studies, but few have been successful in
showing the effects of invasive aquatic plants.
The dispersal of macrophyte mats influences the
dispersal of zooplankton and other aquatic insect
and fish populations (Moore et al, 1994). N.
odorata provides essential habitat for many
frogs, fish, and invertebrates, but there is a
decrease in positive influences on fish species
once 40% of surface coverage is exceeded
(Washington Dept. of Ecology, 2014).
Inhibition of germination or seedling
regeneration of other species can be caused by
N. odorata. These processes often times require
high amounts of energy from sunlight, which
can be limited due to mats of N. odorata (Else
and Riemer 1984). According to a study done by
Figure 6: germination percentage of N. odorata seeds with increasing number
of seeds per container (Else and Riemer 1984). Photo credit: (Else and Riemer,
1984)
H.A. Quayyum and colleagues, the composition
of the leaf petioles and the rhizomes of N.
odorata can suppress germination and growth of
other aquatic species. (Quayyum, 1998). A
portion of the water lily’s rhizome was extracted
and a bioassay was conducted, taking note of the
percent germination of wild rice, and the results
showed a far less percent germination of
seedlings than the control (Quayyum, 1998).
The mats of water lilies result in low amounts of
oxygen in the water column due to less wind
mixing into the water (Civille, 2014). In turn,
this alters the water pH of the littoral zone where
key life stages occur for other aquatic species.
Also, when water lilies die in the fall, the
resulting decay processes uses up dissolved
oxygen as well as adds nutrients to the water.
When the water lilies die, they are digested and
decomposed by microorganisms, which require
oxygen in the process (Moore et al, 1994).
Depending on the concentration of plants, N.
odorata has the ability to lower the oxygen
content of water to 0-2 mg/L of water, which is
not enough or barely enough oxygen to support
most animals (Moore et al, 1994). Good growing
conditions for most aquatic species (with the
exception of some like carp and catfish) require
roughly 4-7 mg/L of dissolved oxygen (Moore et
al, 1994). Higher nutrient and lower oxygen
content triggers increased algal growth, which
decreases water quality (Yang et al, 2008). This
decrease in oxygen content has also been seen to
actually facilitate other invasive species to
establish, one of which being various species of
carp (Frodge et al. 1995). As was stated above,
carp has the ability to live in oxygen-poor
environments. This match up could potentially
result in more species invading and completely
throwing off the equilibrium of the aquatic
community. Most native species cannot adapt
rapidly enough to these environmental changes,
therefore severely decreasing biodiversity of
precious native organisms (Civille, 2014).
Among other impacts, N. odorata has been
known to cause problems and concerns for
humans. The most devastating yet rare instances
are the number of people drowning that can be
attributed to dense plant beds of N. odorata.
Records of drowning due to N. odorata are
difficult to find, but there are two documented
deaths due to entanglement in mats of N.
odorata in Green Lake in August of this year
(Dept. of Ecology, 2014).
Lakefront access can be
restricted due to fragrant
water lilies filling in shallow
areas with soft sediment
(NWCB, 2013). Mats of N.
odorata can make recreation
very difficult, activities
including water skiing,
swimming, fishing, boating,
or even paddling in a canoe.
These are non-market direct
costs of N. odorata, but can
also serve as market direct
costs if the public pays money
to rent a canoe or boat on the
lake (Olden, 2014). Dense
infestations of N. odorata can
clog irrigation ditches,
resulting in slowing water
flow in streams and increasing
water loss through
transpiration (Else and Riemer
1984).
Figure 7: dense mats of N. odorata cover this Minnesota lake in 2010.
Photo credit: http://www.minnesotawildflowers.info/udata
Despite the plethora of negative effects imposed
by N. odorata, there are benefits of the species.
An aesthetic value is a benefit that goes without
saying. Other than that, many eastern Native
American tribes have harvested the rhizome root
of N. odorata for a variety of medicinal purposes
(Briggs, 2006). These include the Chippewa
tribe using the root to treat sores of the mouth,
common colds, and as a digestive aid (Briggs,
2006). Occasionally the rhizomes are used as
food and the lower buds and young leaves were
eaten as a vegetable (Department of Ecology,
2014). In moderate amounts of coverage, N.
odorata cools the water, and offers shelter for
invertebrates and fish. It is a food source for
many animals including beaver, deer, muskrat,
and ducks, and is an essential part of the food
chain in those ecosystems.
The benefits do not outweigh the costs. For a
water quality program in 2013, the Washington
of Ecology spent $25,000 on a single lake (Lake
Sawyer) in the city of Black Diamond to
eradicate fragrant water lily and Eurasian
watermilfoil (Aquatic Weeds Management,
2009). The Aquatic Weeds Management Fund
dished out roughly $466,000 over the course of
one year for the water quality program in an
attempt to control various aquatic plant species
(Aquatic Weeds Management, 2009).
Control Methods
The fragrant water lily has no known
bio-control methods (Dept. of Ecology 2014).
grass carp is a commonly used biological control
method for aquatic plants, but will not consume
the water lily unless there is virtually no other
food available (Civille, 2014). This is backed by
a study of grass carp and the impact it had on
various aquatic plant species. The findings show
that the herbivorous fish had close to no impact
on N. odorata in Washington (Bonar et al.
2002).
Herbicidal control methods are often times used
in the control of N. odorata. These herbicides
include but are not limited to imazapyr, and
imazamox (DiThomasio and Kyser 2013).
Glyphosate (or, N-(phosphonomethyl) gylcine),
is water soluble liquid that has been shown to
have excellent eradication success upon N.
odorata (Westerdahl and Getsinger et al. 1988).
A study done by Welker and colleagues shows
the success of glyphosate on N. odorata. The
experiment included applying different levels of
glyphosate to the leaves of the water lily, and
recorded which level was most effective. It was
found that glyphosate at 2.2 kg/ha resulted in
one full year of complete eradication of mature
water lilies (Welker and Riemer 1982). This
herbicide is applied directly onto the leaves, and
a second application is often necessary for long-
term control (Westerdahl and Getsinger 1988).
The best time to apply glyphosate is when the
plants are actively growing, and results may be
seen only seven days after application
(Westerdahl and Getsinger, 1988).
Unfortunately, this herbicide is non-selective
and can potentially kill other vegetation, so great
care must be taken to apply on only leaves of N.
odorata (Westerdahl and Getsinger, 1988). Due
to the risk posed to other species, the use of
herbicides usually requires a permit from the
state as well as professionally application from
trained companies.
Covering the invaded sediment with opaque
sheets of fabric can accomplish localized control
in areas around docks. This technique blocks
light from the plants, but it is difficult to attach
the fabric to the floor (NWCB, 2013). Lowering
the water level of an invaded area has also been
used to control aquatic plants, but results have
been variable. Studies show that this method of
control only controls about 50% of N. odorata,
and the plants usually recover from propagation
of rhizomes (DiThomaso and Kyser 2013).
Invasion control can also be done by physically
removing the invasive organisms (Olden, 2014).
Manually, pulling out the entire plant including
the rhizome can be successful for a small area if
repeated regularly (King County, 2010).
However, the amount of time and manpower
required to manually eradicate established
populations by pulling is usually unsuccessful.
More professionally done mechanical methods
of control include cutting or harvesting. A
mechanical device connected to a boat often
carries out these actions. Harvesting uses a
specialized boat with a cutting system and
collecting system all in one (Noxious Weed
Control Board, 2013). Underwater rototilling is
a strategy used to remove N. odorata, and
dislodges the large rhizome root system, which
then can be extracted from the water. Rotovation
is a more expensive technique, but usually
results in the permanent removal of rhizomes
(NWCB, 2013). A successful attempt at a Seattle
lake has been documented through the use of
rotovation techniques. Hand held cutting tools
are also used, but it has been found that
harvesting N. odorata is more successful than
cutting. This is mainly due to the extra step in
cutting, which is the removal of the plant from
the water (Dept. of Ecology 2014). Recall that
new patches of N. odorata can arise from a
small piece of a cut rhizome or stem, so cutting
must be done with great precision. Due to this
threat of recolonization, several treatments each
growing season must commence (DiTomaso et
al. 2013).
The fragrant water lily can be prevented from
spreading by cleaning boats travelling between
infested waters, and any other gear dealing with
rhizomes and seeds of the plant. Introduction of
this aquatic plant can also be prevented by
selection of alternate non-invasive species to
place in an ornamental pond area for aesthetic
purposes. If N. odorata must be used for these
ornamental ponds, the pond must not be
connected to any natural body of water, to
decrease likelihood of spread. In 1996-97 on
Lake Lawrence in Thurston County Washington,
the Lake Management District funded an
eradication effort, commercially applying
herbicide to some 80 acres of water lilies
(Civille, 2014). The lilies were then treated
twice each year to continue the efforts, and by
2003, 98% control was obtained in the acres
mapped (Civille, 2014)
Management Objectives and Current
Research
In the state of Washington management
methods are adaptive and incorporate many
levels of actions. These incorporate time
availability, financial support, goals of land use,
labor of participants, and municipal values (King
County, 2010). Research methods are necessary,
as well as development of a legal framework to
carry out the task at hand (Veitch and Clout
2002). Priorities must be set, and selection of the
best control method must occur.
Early detection and prevention is crucial, and
happen to be the least expensive management
options. Looking for fragrant water lilies and
eradicating small patches by hand is being
relayed to the public through education outreach.
Invasive plant identification signs are present
throughout the state of Washington, and display
the proper techniques of eradicating N. odorata
(NWCB, 2013).
Professionally speaking, herbicides are the most
effective management options, noting the high
success rate of glyphosate in the studies done by
Welker and colleagues. Use of this herbicide is
widely accepted in the state of Washington if a
large area is to be removed. Monitoring these
areas being controlled is crucial; otherwise there
is a risk of reestablishment.
Culturally, it is necessary for people to be
cautious when ordering the fragrant water lily
through the horticulture trade, as the system can
be rather faulty. Alternate non-invasive aquatic
plants should be heavily advertised when
purchasing plants for ornamental reasons. This
can be considered a prevention strategy of
management techniques.
Literature Cited
Bonar, S.A., B. Bolding, M. Divens. 2002. Effects of
triploid grass carp on aquatic plants, water
quality, and public satisfaction in Washington
State. North American Journal of Fisheries
Management 22:96-105.
Cook, C.D.K., 1990. Origin, autecology, and spread
of some of the world’s most troublesome
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Regional Contacts
Noxious Weed Control Program
Steven Burke
Noxious Weed Control Coordinator, Program
Project Manager IV
King Street Center-DNRP
201 S Jackson St Rm 700
Seattle WA 98104-3855
206-477-9333
steven-j.burke@kingcounty.gov
Joan Lee
Section Manager
King Street Center-DNRP
201 S Jackson St Rm 600
Seattle WA 98104-3855
206-477-4751
joan.lee@kingcounty.gov
Noxious Weed Control Board
Alison Halpern
Executive Secretary
1111 Washington Street SE
Olympia WA 98504
360-902-2053
ahalpern@agr.wa.gov
Wendy DesCamp
Education Specialist
1111 Washington Street SE
Olympia WA 98504
360-725-5764
wdescamp@agr.wa.gov
Thurston County Lakes Program
Janie Civille
9605B Tilley Road S
Olympia WA 98512
360-867-2327
Washington Invasive Species Council
Wendy Brown
Executive Coordinator
Recreation and Conservation Office
1111 Washington Street SE
Olympia WA 98501
360-902-3088
invasivespecies@rco.wa.gov