Shrubs are woody perennials that grow as specimens or in rows as hedges. They might grow from a few inches to many feet tall, and their foliage might be evergreen or deciduous but, unlike trees, they grow many trunks. Emergent shrubs are a group of shrubs that have adapted to unusual growing conditions. These specialized plants have found popularity as wetland research confirms the important purposes they serve.
Emergent shrubs are woody, multistemmed perennials that have adapted to the soil found in wetlands and watersheds. They can live in areas where the ground is saturated during regular “rainy season” or only occasional flooding. Unlike the plants whose roots lie in submerged , emergent plant roots are subject to both flooding and drought along the margins of rivers, marshes and floodplains.
Wetland plants are called “hydrophytes” have had to adapt to survive. Flooding deprives the soil of oxygen and plants face exceptional challenges posed by wind and water. Emergent shrubs have adapted to wetland and riparian (river and lake watershed) environments, according to scientists in the U. S. Department of Agriculture Natural Resources Conservation Service Plant Materials Program, by developing roots systems and flexible plant tissue.
Emergent shrubs serve important purposes along watersheds and in wetlands. They fix the soil of wetland “uplands” and riparian borders. Their roots help filter pollutants and chemicals as water travels horizontally through the watershed and vertically through the aquifer, the area between the earth’s surface and underlying rock where water gathers in Artesian pockets and moves in underground rivers. They absorb the force of storms, protecting upland soils from erosion and plants from permanent damage. Finally, they trap fertile soil and silt in periods of flooding, depositing it in floodplains before it can wash out of the system into the ocean.
The U.S. Geological Survey lists several shrubby willows, including coyote and yellow willow as emergent woody plants. Riparian shrubs--emergent watershed shrubs--include speckled alder, redosier dogwood, elderberry and chokecherry. Wetland shrubs like bog birch and shrubby cinquefoil form dense thickets around bogs and wooded swamps and suffer both spring flood and summer drought.
The University of Florida IFAS Extension recommends the use of native emergent shrub varieties in wetlands and around water retention areas to protect the water from silting and encroachment of invasive plants as well as the surrounding area from erosion. Native emergent shrubs are better suited to survival in wetland and riparian borders than other shrubs but should be planted less densely because of their large root systems. The shrubs provide a protective environment for wildlife at the water’s edge and their large root systems help retard storm water runoff that may carry fertilizer and encourage the growth of algae in the water.