Dealing with invasive plants
Today when we think of environmentally friendly landscapes we think of low water use, low pesticide use and low green waste. This is called substantial landscaping.
Another factor to truly be an environmentally friendly landscape in the Antelope Valley is that the landscape must be friendly to the high desert environment. Everybody seems to have their favorite plants and many of these plants are from similar regions around the world. Sometimes these plants move out of our landscape and into nature creating a problem to the natural environment. Some plants become invasive and/or use high amounts of water. Some plants grow very rapidly and crowd out native species, which may bring new pests or endanger existing species.
The poster plant of a landscape plant that has gone wrong and is creating major problems in California, including the Antelope Valley, is pampas grass (Cortaderia selloana). In coastal areas it is becoming a major problem; here in the Antelope Valley, it is escaping into the hills and washes.
This large grass plant with the white plumes is very showy, however the seeds can spread for miles. The plant becomes a fire hazard and a habitat for rats. Not planting new pampas grass plants and removing existing plants will probably not stop the rat population in the Antelope Valley, but it can be a step towards protecting the desert environment from future problems.
Another poster plant of the desert areas of Southern California is salt cedar (Tamarisk spp.). These tall lacy trees with wispy pink blooms were planted along streambeds in Palm Springs as windbreaks and to prevent erosion. Today we know that these trees have extremely deep root systems and an enormous thirst.
The tree’s roots can grow down very deeply into the soil, until it reaches the water table and can drink up to 4,000 gallons of water a day in summer. Salt cedars are not as common in the Antelope Valley; however, they are still found here. These trees are quickly spread by seeds and from growing from the roots of existing trees.
Another tree that almost seems to be naturalized in some parts of the Antelope Valley is the Tree-of-heaven. The Tree-of-heaven (Ailanthus altissima) was the tree in the book “A Tree Grows in Brooklyn”. The Tree-of-heaven quickly becomes a weed as it sprouts quickly from the roots causing a mass of trees growing in one spot. Almost as bad as Bermuda grass, it can take years to get rid of Tree-ofheaven as the tree grows back from any roots left behind.
Spanish broom (Spartium junceum) is another shrub creating a problem in the native landscape. Spanish broom is the green shrub with little or no leaves, covered with yellow flowers. Spanish broom sends seeds over a large area, crowding out native plants and reducing the habitat of native animals.
A popular ground cover, Mexican evening primrose, is a very invasive plant. This plant is a desirable ground cover because of the pink poppy looking flower that blooms almost all summer and is considered drought tolerant. However, the plant has a very aggressive root system.
I planted some Mexican evening primrose about 30 years ago, when it started to show up in the nurseries. After a few years, it had moved out of the planters into the lawn, garden and other places we did not want the plant. I am still trying to get rid of it.
Lately, many types of ornamental grasses have become popular. Like pampas grass, many of these grasses are becoming a pest. It seems if the ornamental grass grows well, they will reseed and spread becoming a problem. If the ornamental grass struggles with our environment, then it is less likely to get out of hand, but then it well not be a popular landscape plant.