Warrior plants

I quickly push on the hazard lights as smoke seeps from under the hood of my truck. Pulling over to the shoulder, I call AAA and then wait, sitting among the roadside plants. I feel neither stuck nor frustrated; instead, I surrender myself to the fate of owning a vehicle and dive into the lives of the plants around me.

Sitting there, I am aware of the acrid tinge of burning plastic emanating from my car. A Harley roars by, assaulting me with its fumes and noise. Each passing vehicle floods my senses with toxic smells and blasting winds.

With all of this automotive pressure bearing down on me, I marvel at the tenacity of the roadside plants, these hangers-on of life. Until this moment I took for granted how difficult it must be to live in such a marginal habitat.

Looking around, I notice how hard and impacted the soil is. The gophers and earthworms that aerate the dirt have long since left this hectic place. The ground is littered with rubbish left by random people and construction projects. The street is flat and level, ensuring the road will not flood; little water remains. There is no protection from the sun because all the trees that once lived here were removed to make room for construction.

Dandelions An inhospitable place at best, yet black mustard (Brassica nigra) and redstem filaree (Erodium cicutarium) have made their homes here.

These two plants are often considered "weeds," yet, as they keep me company while I wait on the side of the road, I greatly appreciate their gifts. In a place that seems too toxic for native plants to grow, these warrior plants stubbornly hang on. In doing so, they help to prevent soil erosion and create small microhabitats for other species. Without these "weeds" our roadsides would be desolate wastelands.

Blessing or curse?

Afterward, I did some in-depth research on the term "weed." Often a weed is classified as such for its abundance and its ability to reproduce, compete and spread rapidly. Also included in this classification are plants that are toxic to livestock and humans. A more specific definition, from botanist J.M. Torell, defines "weed" as a "plant that interferes with management objectives for a given area of land at a given point in time." According to this definition, a plant may at times be considered a weed and at other times a blessing.

For example, oleander, which is toxic to both humans and livestock, is highly prized for its ornamental value. Plants that spread rapidly and could take over a given habitat are sometimes considered beneficial because of their ability to live on disturbed sites and to control erosion.

Anatomy of a weed

With greater understanding of weeds, I looked more deeply into black mustard and filaree. Black mustard is a prolific plant introduced by early Europeans. It grows on disturbed sites, hillsides and cultivated fields. It is easily recognized by its bright yellow flower heads, which comprise many smaller individual flowers. Each flower has four sepals, four bright yellow petals and six stamens. The leaves are alternate, the lower being deeply lobed while the upper leaves are toothed. The seed pods (siliques) are long and thin, growing between 0.4 and 1 inch long. Each pod half has a single prominent vein running lengthwise. The stems are erect, with stiff hairs growing on the lower portions. Black mustard is an annual reaching 2 to 8 feet in height.

Unlike the tall mustard, redstem filaree, also known as stork's bill, only grows from 1 inch to 2 feet high. Stems may be erect or spreading and generally originate from a basal rosette. Leaves are feather- or fernlike, with pinnately lobed or toothed segments. Both stems and leaves are hairy. The five petals are purple/pink with five green sepals. The seeds are five-lobed and long-beaked. As drying occurs, each lobe curls and splits away from the others. This plant, native to Europe or Asia, was brought here for forage. Filaree was once thought to be native to California because records of it date back to 1771. It is now understood to be one of California's earliest introduced plants.

When comparing these two plants, I wonder why they are so effective at thriving in hostile environments. For black mustard I surmise it is due to the great number of flowers produced as well as the number of seeds/seed pods. A single plant of black mustard will produce hundreds of pods, many containing multiple seeds; therefore, it's possible to have thousands of seeds per plant. While filaree is also prolific, its seeds are excellent at dispersal. Their screwlike shape makes them excellent hitchhikers, as well as phenomenal diggers once they find adequate soil.

I find it interesting that these plants are dubbed a nuisance or "weed" when they carry the very trait that so many Americans strive for- prolific abundance.

Meghan Walla-Murphy can be reached at the following e-mail: mwallamurphy@yahoo.com.