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. 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 ⁶

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 Project ⁶

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

Contributed by J. Hull

Towson University Glen Arboretum