|
Some
Ornamental Plants Become Exotic Pests in the Wild Have you ever experienced the thrill of a new plant thriving in your garden, only to regret ever planting it because too many of its descendants popped up where you didn't want them? All over California, natural wildlands and parks are under attack from invasive plants that started out harmlessly in our home gardens then escaped into the countryside and went wild. It's not that all ornamental plants pose this threat, but certain ones are capable of getting established and taking over hundreds and sometimes thousands of acres. Many of these "exotic" plants came from Europe or Asia and were brought to this country by our ancestors. As native habitat is replaced by exotic plants, many species of birds, insects, fish and other wildlife are displaced or lost. People are affected too. Pest plants that invade riparian areas often clog our waterways so that water cannot move down the river or stream. Others use much more water than native species use to grow. Riparian pest plants are essentially robbing water from people and wildlife. Pest plants that invade ravines, foothills, and chaparral areas often pose a greater fire threat than native species because they increase wild fire frequency or because they pose a bigger fuel threat. It has been estimated that invasive pest plants cost California hundreds of millions of dollars annually. The California Exotic Pest Plant Council (CalEPPC, pronounced Calepsy), whose membership includes land managers, consultants, scientists, planners, non-profit organization volunteers and others, is an authoritative source of new information on all aspects of wildland weed management. The Council has developed a categorized list of exotic plant pests, which includes many of the ones commonly grown in our own gardens. Their list gives both the common and botanical (Latin) names,
the habitats of concern, and the geographical distribution of
each plant. The list is further divided into sections dealing
with the most invasive, lesser invasive, explosive (rapid) potential
to spread, unsure about spread (not enough information is currently
available about the plant), annual grasses that pose significant
threat to wildlands, and those plants (after a status review)
that don't appear to be a threat. The list is downloadable from
the website: www.caleppc.org, or a copy may be obtained by contacting
CalEPPC at 555 Magnolia Avenue, Petaluma, CA 94952-2080. Tree-of-heaven (Ailanthus altissima) should be renamed the tree-of-hell because its root system is very invasive and the tree is very difficult to get rid of where it is not wanted. It is very tolerant of our valley climate and is a familiar site along roadways on the valley floor and through the foothills. It invades riparian areas, grasslands, and oak woodlands. Its leaves are similar in shape to the Raywood ash, Chinese pistache, or black walnut tree. If you ever read the book "A Tree Grows in Brooklyn", it so happens that was a tree-of-heaven. What should you do if you have some of these invasive plants in your garden? There's no need to rush right out to get rid of them, especially if they are suited to your landscape and property. But you should be aware that they pose a threat to the countryside, if they escape from your yard. Many of us have backyards that border riparian areas, vacant lots, or neighboring farmland and pastures. You can use the runaways to your advantage on your own property, but please be careful with California's property. Try to stop the invasion before it starts. December 26, 2002 |