October to November is the time of the year when cotton bales are seen in bunches as we drive to and from work. Despite that, there’s still a lot of white out there. Large feathery shrubs dominate the roadside scenery.
I call them groundsel tree (Baccharis halimifolia), but other common names are sea myrtle, salt bush and silverling. The fluffy white stuff is attached to the seeds like dandelion down. In a few weeks the wind will spread them around the same way.
Semi-evergreen toothed leaves emerge from the stem singly. Size varies from less than an inch long to nearly three. Bark is brown with intersecting ridges.
Groundsel tree plants can be identified at quite a distance. One of the few shrubs flowering now, they are often 10 to 15 feet tall. This makes them difficult to ignore. No other member of the sunflower family in North Carolina gets this big.
This weedy shrub is well adapted to wet areas. We often see it interspersed with wax myrtle. Groundsel trees also tolerate salt quite well and can stabilize disturbed sites near the coast. They make a great naturalizing backdrop for a landscape.
They also establish easily. High seed germination percentage and prolific seed production are the main reasons why.
Flowering is much more prolific in sunny areas, but plants can survive in the shade. Thinning of a dominant tree canopy will encourage them to flower.
Plants are dioeceous, meaning that male and female flowers reside on different plants. Male plants are smaller and much less noticeable than the female ones. Female plants can produce viable seed within three years.
Other than retarding erosion and providing pleasing fall interest, Groundsel trees have little agricultural value. There’s nothing on the plant suitable for human foraging. Livestock and wildlife don’t even eat them. This is good, since foliage contains chemicals toxic to livestock. Pastures can fall prey to their invasion if farmers allow animals to overgraze and create bare places.
Although groundsel tree apparently has little or no value as a good food source for game animals, it serves as cover and nesting habitat for various species of birds. Nectar from male flowers provides abundant food for bees and small butterflies. Songbirds then feast on the insects.
These fast-growing shrubs can pose problems during reforestation. They compete with young tree seedlings for light and usually dominate. They don’t respond well to fire, so incorporating prescribed burns into a forest management plan can eliminate this competition problem.
Chemical control is difficult. Many herbicides that will control groundsel tree will also kill desirable hardwood species. Spot treatments might be the best option for homeowners, but that’s tedious.
When in flower this plant can be a nuisance to some, because the airborne pollen is a potent allergen like ragweed. Susceptible individuals should avoid it in the fall. Likely the shedding down will irritate nasal passages also.
This is one species that is great when it is in its proper place. The cottony masses can be breathtaking when cruising down the highway in mid to late fall.
Ted Manzer teaches agriculture at Northeastern High School.