A ruderal species is a plant species that is first to colonize disturbed lands. The disturbance may be natural — for example, wildfires — or the consequences of human activities, such as construction of roads and building, or agriculture such as abandoned fields. The term ruderal originates from the Latin word rudus, meaning “rubble.” Many flowering plants in disturbed sites are weedy, naturalized non-natives. The list is long: Henbit, common dandelion, wild carrot, yarrow — just to name a few. These weeds have found their niche.
Because the first cities in North America were seaports, many non-natives slipped in and gained footholds. As native habitats were altered, non-native species gained footholds. Ditches were drained, woods were cleared, swamps were banked to grow rice. Lakes formed for electrical power became ideal sites for naturalized plants. Of course, not all non-natives are accidents. Numerous species were purposely brought as ornamentals or soil-builders. Whatever the original intent, many ruderal plants have naturalized to the point of acceptance, or at least tolerance.
Many ruderals slipped in from Europe and Asia. Common chickweed is from Eurasia. It can be invasive but not to the point of replacing native vegetation. I find it extremely satisfying to pull up chickweed and throw it to my daughter’s hens. Henbit is another common weed found in most pastures and abandoned fields. This non-native mint naturalized from Europe. Common dandelion is now naturalized throughout the U.S., in lawns, vacant lots and along roadsides. It’s a versatile plant, used as medicine and food. Bachelor button or cornflower is naturalized from Mediterranean Europe. Its blue flowers show up reliably in May and June in fields and along roadsides. Fortunately, many naturalized ruderals do not create problems for gardeners.
Unfortunately, other transplants can be invasive. Mimosa, popcorn tree, rattlebox, Princess tree and kudzu all illustrate what can happen when a seemingly good plant becomes an aggressive and obnoxious non-native. Mimosa, or silk tree, was introduced into cultivation from Asia. It is now a serious weed in the Southeast often found around abandoned homesites. Japanese honeysuckle has become invasive since first introduced from Japan. Common along fences and woodlands, it can replace native flora. Princess tree (Paulownia) is native to central China. Introduced in 1834 as an ornamental, it has spread far and wide, invading native woodlands. Infamous kudzu is an invasive transplant too.
Not all ruderal plants are non-natives. Ruderals also include natives like butterfly weed which feeds summer butterflies and catalpa trees which provide the bream fisherman with bait. Morning glory, native to tropical America, is widely naturalized. Evening primrose, native to the west, is drought resistant and perfect for dry areas. Black-eyed Susan is another western native that spread eastward and blooms profusely in Southern gardens. Passion-flower is a beautiful native welcomed by most of us. And our native goldenrod is one of our most abundant ruderal plants found in abandoned fields, pastures, and along roadsides.
Learning to identify ruderal weeds, vines and flowers — whether native or naturalized — is a way of learning the history of flora. For example, Jimson-weed may come from South America; another source points to Europe, and yet another claims that it was growing at Jamestown in 1676. There are some interesting stories about the early uses of Jimson-weed at Jamestown.
Ruderal plants are adaptable and resilient. They offer biodiversity, attract pollinators and promote ecological restoration. These tough species possess an extraordinary capacity for survival, which is why they are often found in disturbed environments such as roadsides, vacant lots, abandoned crop fields and places affected by fires. Ruderal plants like ragwort can be a hidden gem for ecological restoration. Occasionally problematic, especially when they compete with preferred commercial crops, in many environments the ruderals fulfill beneficial functions. Many ruderals are an essential source of nectar and pollen for bees, butterflies and other insects. They provide shelter and food for birds, small mammals and invertebrates. They quickly colonize eroded areas, reduce soil loss, and improve the structure and fertility of the subsoil with their roots.
While some may wish that the more weedy and invasive ruderals would disappear, when I drive down highways and byways, I cannot help but admire the many ruderal communities now blooming almost everywhere.
The Aiken Master Gardeners will hold a lunchbox lecture at noon on Friday, May 22, at Millbrook Baptist Church. The speaker will be Andy Cabe, director of horticulture at Riverbanks. He will will speak Riverbanks Gardens. Millbrook Baptist is located at 223 South Aiken Blvd.
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