Beach Plum

Prunus marítima Marshall

Description

Also called seaside plum, sand plum, and graves plum, this is a member of the rose family (Rosaceae) ¹. Usually a multi-stemmed shrub, beach plum can grow up to 18 feet ¹. Its reddish-brown stems have conspicuous horizontal lenticels when young but becomes rough with age ¹. The leaves are oval shaped and up to 2.75 inches long with finely serrated margins ¹. They are dark green above and finely hairy on the lower surface ¹. The flowers appear before leaf out in early spring and are white, one-half inch across and occur singly or in small groups ¹. Individual plants are self sterile ². The dark purple fruits may be up to one inch in diameter and mature in late summer ¹.

A cluster of small, white beach plum flowers with green pistil sprouting from the center, stemming out from a single brown branch.

Flowers of beach plum. Native Plant Trust ⁴

Several smaller branches grow out perpendicularly from a long, thick, grayish-brown main branch. Bright green, jagged-edged leaves sprout from them. Hanging beneath the leaves are lone or bunches of dark reddish-purple plums, many with a dusty coating

Beach plum fruit and leaves. @ K. Wixted*, Maryland Biodiversity Project ³

Distribution

Beach plum occurs along in sand dunes along the Atlantic coast from Canada to Virginia ¹. It is intolerant of flooding and is naturally found in areas protected from salt spray such as mature sand dunes ¹. It can be planted in other well drained, sunny areas ¹. Beach plum is considered endangered in Maryland³ as well as in Maine and Pennsylvania ¹. In Maryland it occurs from Anne Aruncel to St. Mary’s County on the Western Shore and in Kent and Worcester Counties on the Eastern Shore ³.

Distribution map of beach plum ⁵

Wildlife Importance

Beach plum thickets provide a nesting location for Glossy Ibis as well as food for numerous bird species ¹. It is pollinated by bees and numerous other insects ¹. It is a host plant to the Laurel Sphinx Moth ³. A bright green Laurel Sphinx Moth larva crawls along the underside stem of a green leaf with brown splotches. The larva has black and light blue diagonal stripes along its sides and a light blue tail speckled with black horns.

Laurel Sphinx Moth larva. @ B. Cammarata*, Maryland Biodiversity Project ³

An adult Laurel Sphinx Moth laying on a dusty brown rock. The moth has a light brown body with white and black markings along it's sides. It's wings span diagonally from it's body, colored with tan, dark brown, and white markings.

Adult Laurel Sphinx Moth. @ M. Tillett*, Maryland Biodiversity Project³

Economic Importance

Beach plums are used commercially for producing jams and jellies ¹. It is also used for horticultural purposes due to its ability to grow in poor nutrient, sandy soils ¹. Beach plum can have high ornamental value ².

Threats

Beach plum is susceptible to several insect pests including the plum gouger, plum curculio and European red mite ². The plumb gouger can reduce the fruit yield by one half ². Several fungus infections affect beach plum include plum pockets, brown rot and lead spot ².

Interesting Facts

The flowers turn from white to a slight pink hue upon successful pollination ¹.
Beach plum can produce adventitious roots from stems that enable it to survival burial in sand dunes ¹.
Beach plum sets flowers each year, but bears fruit only once in every three or four years ².

References

* Imaged used with permission of photographer.

Contributed by J. Hull

Towson University Glen Arboretum