A stable sand dune is one characterized by a diversity of vegetation. The most conspicuous and probably the most important species is beach grass (Ammophila breviligulata). This native grass grows up to three feet tall, and the leaves form clumps that trap blowing sand, holding the small particles in place. This prevents erosion and the movement of dunes onto roads. The plants also spread with underground rhizomes that send up shoots which add to the dune’s stability.
There are several other plants that are also found on a sand dune. A common shrub is the salt spray rose (Rosa rugosa). Though this is an introduced species, its red fruits, called rose hips, are a food source for several animals. In addition, the salt spray rose also helps control erosion and is quite attractive with its large white, pink, or red flowers. The rose hips have been used as a vitamin-rich jelly.
Another dune shrub that has had a history of commercial use is bayberry (Myrica pensylvanica). The slightly round leaves have small teeth on the tips. The fruits are ball-shaped and gray. They appear waxy to the touch, and this feature helps protect the plant from dehydration. These berries have been used to make aromatic soaps and candles.
A smaller branched shrub with scale-like leaves often grows in patchy mounds on a sand dune. This is called poverty grass or beach heather (Hudsonia tomentosa), and is one of the few evergreen plants in this habitat. The small yellow flowers can be seen in the summer. The plant has a grayish tinge to it, and sometimes grows in very dense patches.
There are two common dune plants which belong to the genus Artemisia. Dusty miller (A. stelleriana) has distinct grayish-green leaves that are covered with small hairs that function to protect the plant from dehydration. This plant also puts out a long spike of yellow flowers in mid to late summer. However, it is the lobed foliage that makes it an ideal addition to gardens. Its relative is wormwood (A. caudata) which has pinnate leaves that grow close to the substrate. Less conspicuous than dusty miller, wormwood also produces small yellow flowers in the summer.
Growing at the base of the dunes is a colorful legume called the beach pea (Lathyrus japonicus). This plant lies low on the ground and exhibits bright purple flowers in the summer which are followed by the typical fruits of a pea plant. This is another plant that is adapted to the dry, sandy soil, and the small leaves spread out at the dune’s edge.
In many areas in the northeast goldenrod is one of the most visible and showiest wildflowers. However, there is a species that has adapted to the harsh dune environment, namely seaside goldenrod (Solidago sempervirens). This plant can grow several feet high and produces the bright yellow flowers in late summer to early fall. The leaves are thick and up to a foot in length which helps retain water. The flowers are often visited by large numbers of insects that assist in pollination.
We end our dune tour with one of my favorites, the hardy beach plum (Prunus maritima). Known for its delicious fruits which are made into jams and jellies, beach plum also produces showy white flowers in late spring. The dark purple fruits appear later in the summer. The leaves on this shrub are toothed, and the plant, like so many others in this habitat, is good for erosion control.
Copyright Gil Newton 2009 Thanks to Chris Dumas for logo image.