Written by Collin McMichael, Education Coordinator
Buttonbush may not be a tree, per se, but it is an important enough woody, riparian species that it deserves its own Tree of the Month. Buttonbush generally falls in the informal size class of “shrubbery”. Buttonbushes never really make it past 12 feet tall, though it can sometimes make it fully into a “treelet”, towering over everything at a whopping 20 feet. Regardless of its diminutive stature, buttonbush serves an important ecological function in riparian biomes.
Being riparian means buttonbush is most at home in wetter habitats. It is usually found on stream sides or near ponds and boggy areas. Many riparian plants in Central Texas can be difficult to establish due to herbivory either from deer or beavers. Cows can also cause a problem in agricultural areas. Buttonbush, however, has toxic, unpalatable leaves that prevent herbivory from ungulates and bitter, poisonous bark that precludes beaver damage, allowing it to establish readily in its natural habitat.
When established, buttonbush, along with many other riparian species, can stabilize banks and increase water quality. Stabilized banks from riparian plant cover can prevent the deeply incised creek beds so prevalent in eastern Travis County on Blackland Prairie lands. These deeply cut stream beds can increase water speeds thereby increasing erosion. Once this run-away erosional process takes hold, the streambed quickly ends up deeper than the plant roots can reach, impeding the growth of a healthy riparian corridor. When a population of streamside woody plants is present, rainfall is slowed by the canopy and plant stems and roots allow the water to penetrate the soil more evenly during flood events, thereby preventing erosion that would otherwise increase stream turbidity.
The Blackland Prairie, while technically a grass-dominated ecoregion, historically had riparian forests following each stream. While it may be hard to find today due to habitat degradation, buttonbush was and is a native species to this region. It is the goal of TreeFolks’ newest program, the Travis County Floodplain Reforestation Program, to reintroduce these important habitats and species to the Blackland Prairie through riparian reforestation techniques that we have perfected with our disaster recovery work in Bastrop and Hays Counties. We aim to improve stream quality and wildlife habitat in the region while also enhancing the human health benefits associated with increased tree cover. Furthermore, we will be simultaneously generating carbon credits to help Austin meets its 2020 carbon neutrality goals. More information on this program can be found online at treefolkstest.wpengine.com/travis-county-floodplain/.
While our newest program may be restricted to Eastern Travis County, buttonbush is not. The Latin name, Cephalanthus occidentalis, translates literally to eastern flower-head due to its distribution and showy blossoms. Its native habitat is throughout Texas and much of the eastern half of the country up to Canada, but it is now distributed across much of the United States as it is a very desirable species both in riparian restoration work and urban plantings. The flowers themselves are rather unique, appearing in June as white to light pink pincushions. Once fertilized, these flowers become clusters of nutlets that persist even when the bright-green, oppositely arranged leaves fall for the winter revealing the bush’s attractive, red bark.
The flowers of buttonbush attract many butterflies and other insects including honeybees. In fact, buttonbush is commonly planted as a honey plant near apiaries. The nutlets showing up in the fall are consumed with gusto by migratory waterfowl such as ducks and geese. Birds also approve of its open, twisted growth habit resulting in nests in its upper branches.
Buttonbush is an excellent “tree” for Central Texas, especially if you are looking for a smaller plant in a site with poor drainage. In urban landscapes, it can appear less attractive after several years as it tends to abhor the compact growth habits of most people’s favorite plants. In order to keep it a standard bush form, it can be cut back to the ground every few years. This may even increase its flowering the following year. If left to its own devices, buttonbush can become a stately small tree with an interesting, architectural shape, and these plants do ultimately seem the happiest when allowed to naturalize in the home garden.