Rare and Invasive Plants
Legal definitions of being rare
Endangered Species Act (1973)
•Directs government agencies to use whatever means necessary to preserve the species in question.
•Requires that “critical habitat” be protected, whether on public or private land
•Petitions for being “listed” are submitted to US Fish and Wildlife Service (except for marine fishes, which go to the National Marine Fisheries Service)
•Endangered: a species which is faced with extinction in all or much of its range
•Threatened: a species which is likely to become endangered
•Concern: a species whose conservation standing is of concern to the U.S. Fish and Wildlife Service, but for which status information is still needed.
•Candidate: the U.S. Fish and Wildlife Service has sufficient information on file to consider for listing as threatened or endangered.
What are primary threats to rare species?
•David S Wilcove, David
Rothstein, Jason Dubow, Ali
Phillips, Elizabeth Losos. 1998. Quantifying threats to imperiled
species in the
What if a species is rare in
•Washington Natural Heritage Program, managed by Washington Department of Natural Resources, keeps its own lists
•Endangered: In danger of becoming extinct or
•Threatened: Likely to become endangered in
•Sensitive: Vulnerable or declining, and could become endangered or threatened in the state.
Extinct or Extirpated in
•Review: More information is needed to accurately assess their status.
This status is assigned to each vascular plant taxon
that is more abundant and/or less threatened in
State listing offers no legal protection.
43 plant species are listed as endangered by the Washington Natural Heritage Program. Four of those are listed as endangered at the Federal Level.
bradshawii (Bradshaw's desert parsley, family Apiaceae) was formerly abundant in the Willamette Valley of
Oregon and adjacent areas of
Primary threats: formerly agriculture, currently development
Hackelia venusta (showy stickseed) is a perennial, herbaceous
plant in the Borage family (Boraginaceae).
The plant is a short, moderately stout species, 8 to 16 inches in height, and forms 5-lobed, white flowers.
•Showy stickseed grows on sparsely vegetated, granitic scree on unstable, steep slopes on the east slope of the central Cascade Mountains of Washington.
•The species has always been restricted in its distribution, the one population is found entirely on USDA Forest Service land.
•This is the rarest plant in
•Reasons for listing:
•One location that occurs on less than one hectare (2.5 acres).
•Surveys conducted in 2001 observed approximately 500 plants.
•The major threats to the species are:
•physical disturbance to the habitat
•changes to the composition of the plant community brought on by fire suppression
•In addition, highway maintenance activities, low seed production, poor germination, competition from native trees and shrubs, and nonnative noxious weeds that encroach upon the habitat of showy stickseed threaten the species.
Biological reasons for being rare:
•low seed production
•limited vegetative reproduction
•dioecious with scattered populations
•pollinators not available
•limited seed dispersal
•limited environmental tolerance
Cultural reasons for being rare:
•habitat threat - development, agriculture, logging, ...
•introduced disease, predator, invasive plant...
Rare Plant Care and Conservation in
•Reintroduction to native habitats.
•Monitoring of rare plant populations
•Training of students and volunteers
•Education of general public
2008 Monitoring Results
•125 population surveys
•At 64% of the sites, the monitor(s) found and documented the rare plant occurrence.
•36% could not be found
•37 of the 80 rare plant populations found consisted of fewer than 50 individuals
•Invasive species at 39% of the sites
•Land use and management concerns at 39% of the sites
Three new locations for rare plants
24 individuals in the
•100 individuals of Polemonium
viscosum in the Pasayten
Wilderness of the
•22 clumps of Silene
seelyi were observed on a cliff in the Wenatchee
River Ranger District of the
On the other hand...
•Invasive non-native plants
•A “weed” is a plant growing where you don’t want it to be.
•Invasive non-native (or exotic or alien) plants are those that can or have spread into native wilderness or managed ecosystems, develop self-sustaining populations, and become dominant or disruptive to those systems.
•How long must a plant be here to be considered native?
•Pre-European contact, about 400 years.
•A noxious weed is ”a plant that when established is highly destructive, competitive or difficult to control by cultural or chemical practices"
original purpose behind
State Noxious Weed List
Class A Noxious Weeds:
Non-native species that are limited in distribution in
Non-native species that are either absent from or limited in distribution in some portions of the state but very abundant in other areas. The goals are to contain the plants where they are already widespread and prevent their spread into new areas.
Non-native plants that are already widespread in
How do invasive organisms get here?
•Accidentally imported with international trade
–Eurasian water milfoil
–plant pathogens such as Chestnut blight and Dutch elm disease
Beware of wildflower mixes
•Grew 19 packets of “wildflower mixes”
•Each contained from three to 13 invasive species
•Eight had seeds of noxious weeds
Features of invasive plants
•high seed production
•extensive vegetative reproduction
•pollinated by wind or other abundant agent
•small seeds with effective seed dispersal
•broad environmental tolerance
Problems caused by invasive plants
•displace native species
•change ecosystem processes
–increase storm damage
•Native to Mediterranean region
•arrived as a seed lot contaminant
•spread around the country in straw that was used in trains as packing material
•Annually, cheatgrass costs wheat farmers an estimated $350-370
million dollars in lost yields and control costs in the western
•Also affects natural areas
Birds of Prey National Conservation Area,
•cheatgrass is flammable, promotes fire
•fire eliminates sagebrush
•prey for raptors disappears
•Tansy ragwort is toxic
–lethal to cattle and horses
–to a lesser extent goats
•contains several alkaloids toxic when broken down by liver
•Irreversible liver damage, including liver cancer
•Human potentially affected through contaminated herbal remedies, flour, milk, or honey
•Chemical control is effective against tansy ragwort
–(2,4-D and others)
•Hand pulling is effective on small infestation sites
•Mowing is not recommended
•Biocontrol Potentials: In its native range (
natural enemies of tansy ragwort were introduced in
–ragwort flea beetle (Longitarsus jacobaeae)
–ragwort seed fly (Pegohylemyia seneciella)
–cinnabar moth (Tyria jacobaeae)
•Introduced in 1876 at the Centennial
•The Japanese government constructed a garden with Japanese plants.
•The large leaves and sweet-smelling
blooms of kudzu were attractive, and US gardeners started growing the plant
Grows 60 ft/ summer
•Introduced as a highway beautification project
•Member of the pea family
•Nitrogen-fixing bacteria associated with root nodules
•Allows plant to successfully invade nutrient-poor sites
•High N remains in soil following plant removal – alters nutrient cycling long-term
•Common in disturbed areas
•Adventitious roots cling to brick buildings
to give “old world” feel to
•Successful invader by vegetatively spreading into any environment
•Seed dispersal in berries by birds
•Chokes out most understory vegetation, climbs bark of trees, increases storm damage
Which tree is more likely to fall in a windstorm?
Invasive species survey recently completed at Seminary Hill Natural Area
•Introduced in the early 1800's as a garden ornamental
•escaped into wetlands
•displaces the native vegetation like cattails that acts as food for native wildlife
•native pollinators prefer loosestrife to native plants, reducing seed production in native species