Weeds of Kamiak Butte"A weed is a plant whose virtues have not yet been discovered."
Ralph Waldo Emerson
Emerson's notion of weeds may be reasonable: If you ask friends, the weed of one will be a beautiful wildflower of another. Many botanists avoid describing any plant as a 'weed' because they fear the term is too subjective. Some botanists describe weeds as plants that grow in places in which people do not want them.
Herbert Baker (1974), a student of weeds, suggested that we can identify characteristics commonly found in weeds, including the following:
- Seeds will germinate in, and plants can live in, many different environments.
- Seed germination is not strongly controlled by environment and can occur in different seasons.
- Seeds have great longevity.
- Plants grow rapidly to the reproductive phase.
- If perennial, the plants have modes of asexual reproduction.
- If perennial, the plants have underground perennating structures that are not easily removed from the soil.
- Plants have good interspecific competitive abilities.
- Plants produce seeds over much of the growing season.
- Plants are self-compatible, but do not reproduce entirely by selfing.
- Pollination (or gamete transfer more generally) occurs via vectors such as wind or unspecialized pollinators.
- Plants that grow in various environments can produce seeds.
- Plants have high seed output.
- Seeds are readily dispersed over both short and long distances.
Baker (1974) chose to define weeds as plants whose population growth in any specified geographic area results predominantly from disturbances caused by humans.
We can think about Kamiak Butte as surrounded by human disturbance because it sits amid agricultural land. The grazing of cattle and sheep on Kamiak Butte before it became a park created significant disturbance and has altered the flora of the south slope. A limited amount of logging and timber cutting for firewood prior to the designation of Kamiak Butte as a park created disturbances on the forested north slope. More localized human disturbance on Kamiak Butte is found along roads and trails. All of these disturbances have permitted a large number of "weedy" plants to establish themselves on Kamiak Butte.
One of the most basic disturbances caused by humans is the introduction of plants from outside areas into new areas. These so-called 'introduced plants' are especially common weeds in agricultural areas. Introductions from Europe and Asia account for many of the weedy plants that have spread to Kamiak Butte, including the following:
In addition to plants introduced from outside regions, some native plants of the American West are also considered by some to be weedy in our area (including Kamiak Butte). These native "weeds" often have many of the characteristics listed above and tend to colonize and persist in areas disturbed by humans. Native plants on Kamiak Butte considered by some to be weedy include:
Pteridium aquilinum: Bracken fern is often thought of as a weed because it grows in a wide variety of environments and can be difficult to eradicate because it has extensive underground parts that function in asexual reproduction.
Anaphalis margaritacea: Pearly everlasting tends to rapidly colonize open disturbances and burn areas.
Apocynum androsaemifolium: Spreading dogbane is a woody shrub that colonizes disturbed areas. It is often considered weedy because it is difficult to eradicate in pastures and orchards.
Aster occidentalis: Western aster is considered weedy because it invades pastures and meadows. It is common in disturbed areas and spreads readily along roadsides.
Barbarea orthoceras: Winter cress spreads rapidly along roadside ditches and in moist disturbed areas.
Epilobium angustifolium: Fireweed can be found in dense patches in open disturbed areas. It is one of the most well known plants of the Pacific Northwest because its showy pink flowers are commonly seen along roadsides and in forest openings. The plant is a quick colonizer and spreads via underground rhizomes. It flowers at length over the growing season and produces seeds that are readily dispersed by wind.
Lactuca pulchella: Blue lettuce is frequent problem in cultivated fields. It has an underground perennating structure that can be difficult to remove. The underground structures function in asexual reproduction, but the plants also reproduce sexually and disperse their tufted seeds readily by wind.
Solidago canadensis: The Canada goldenrod spreads by asexual propagation using underground rhizomes to form large, dense stands. It commonly colonizes and persists in disturbed areas. It is often considered weedy by those who do not want the dense populations in pastures.
To learn more about the biology of weeds and those plants that are weedy in the Pacific Northwest, the following references may be helpful:
Baker, H. 1974. The evolution of weeds. Annual Review of Ecology and Systematics 5: 1-24.
Gaines, X. M. and D. G. Swan, 1972. Weeds of Eastern Washington and Adjacent Areas. Camp-Na-Bor-Lee, Davenport.
Gilkey, H. M. 1957. Weeds of the Pacific Northwest. Oregon State College, Corvallis.
Taylor, R. J. 1990. Northwest Weeds. Mountain Press Pub. Co., Missoula.
Whitson, T. D. et al. 1991. Weeds of the West. Pioneer of Jackson Hole, Jackson.