    
|
  |
Invasive SpeciesInvasive plants may be the greatest threat to native plant and animal communities. According to Sandy Diedrich of the No Ivy League, we lose 4,600 acres of habitat a day to invasive species. Since they evolved in a different locale, invasive species have limited natural population control mechanisms. They are also well adapted to disturbed environments, which allows them to quickly spread and prevent the successful reproduction of native plant species by competing for water, sunlight, space and nutrients. Since native insects, birds and mammals have evolved to be dependent on native plant food sources, invasive plants also harm wildlife populations. Once established, invasive plant species can be extremely difficult and expensive to control. You can help by not planting invasive species in your yard and by volunteering with local environmental groups at invasive species removal work parties. Our Natural Area Restoration program offers volunteer opportunities during the summer and fall to remove invasive species and to mulch and water newly planted trees and shrubs. Below is a partial list of invasive species. You can visit our invasives search page to learn about other invasives. 
Reed canary grassPhalaris arundinacea Family: Poaceae This is the most invasive grass species in wetlands of the Pacific Northwest. It is a rhizomatous, mat-forming perennial, which takes over wetland habitats. It is especially fond of wet, disturbed areas. Reed canary grass is a native of Eurasia. It was widely planted in this area between the 1930s and 1980s for erosion control. Characteristics:
Himalayan blackberryRubus discolor Family: Rosaceae Himalayan blackberry was introduced from Asia by way of England. It prefers disturbed, open, upland sites. It is readily spread by birds and animals, as its fruits are delicious! Characteristics:
English ivyHedera helix Family: Apiaceae English ivy is a familiar vine, often planted in yards. It thrives in the low-light conditions of Pacific Northwest forests, and is especially prevalent near settled areas. This vine often takes over the forest floor and climbs trees. It out-competes and ultimately kills many native plant species by shading them from light. It is not a good food source for wildlife, nor is it an effective erosion controller, as is commonly believed. Characteristics:
English hollyIlex aquifolium Family: Aquifoliaceae English holly is an escaped ornamental which often invades upland forests and the edges of wetland areas. Its bright red fruits are dispersed by birds. English holly often grows into a tall, thick-trunked tree. Male and female flowers are borne on separate trees. Characteristics:
Purple loosestrifeLythrum salicaria Family: Lythraceae Purple loosestrife is a perennial shrub that grows in both brackish or fresh wetland areas, preferring to "keep its feet wet" under a couple inches of water. It is a Eurasian native that has spread over much of North America through ornamental plantings. It can take over wetland areas, out-competing native plant species. It spreads easily by seed, cuttings and runners. Characteristics:
Scots broomCytisus scoparius Family: Fabaceae Scots broom is most often found in disturbed sites, but will invade other open areas. This plant contains a toxin that can adversely affect the heart and nervous system, causing severe reactions in children. When the seeds break apart, the pod halves contort in different directions, producing an audible snap. Characteristics:
|
|