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

aquatic weeds. Pp. 31-38. In: A.H. Peiterse and

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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