In Search of the Beach Plum


With the amazing weather we’ve been having in New England, we decided to drive up to Plum Island, where the mouth of the Merrimack River meets the ocean. The island is home to multiple conservation sites, including the Parker River National Wildlife Refuge on the largest part of the island, the Sandy Point State Reservation at the southern tip, and the Joppa Flats Education Center on the mainland opposite the island. Plum island has a five mile long stretch of pristine beaches, dunes, pathways, tidal pools, and marshes. It provides a range of opportunities for nature lovers, including birding, fishing, and exploring.


The dunes of Plum Island reach fifty feet in height–some dramatic and visibly eroded, and some rolling and gradual, covered with vegetation. One plant in particular, the beach plum (Prunus maritima), became the main focus of our trip. The namesake of the island, the beach plum is a hardy species of Prunus well suited to the exposed dunes, salt spray and severe coastal weather. Forming rough and twisted trunks, these shrubs provide a valuable service for the island–their extensive root systems anchor much of the surrounding soil, preserving the landmass and allowing for the establishment of neighboring species.


The dunes of Plum Island are home to many interesting species of trees and shrubs. On the exposed outcroppings, plums, sumac, eastern red cedar, and black cherries form dense thickets.

Staghorn Sumac (Rhus typhina) branches

The bare branches of staghorn sumac (Rhus typhina), naturally shaped by the elements, reach upward like twisted woody fingers.

Beach Rose (Rosa rugosa) autumn foliage

With the warm weather, many vigorous beach roses (Rosa rugosa) were still in the process of shedding their striking fall foliage, some with fully ripened rose hips.

Northern Bayberry (Myrica pensylvanica) berries

These thickets are also home to northern bayberry (Myrica pensylvanica), from which the colonists extracted a sweet smelling wax used to make candles. The oils of bayberry foliage and fruit are still used in a range of aromatic products.

Common Mullein (Verbascum thapsus)

The dunes are home to a number of perennial plants as well. Common mullein (Verbascum thapsus) is still growing in the warm weather. We saw many with their tall seed spikes still intact.

Yarrow (Achillea millefolium) flowers

We were interested to find yarrow (Achillea millefolium) flowers still blooming among the leafy debris. Our yarrow at home succumbed to cold weather a month ago. Perhaps the coastal individuals are more suited to rugged environments than were our nursery stock.

Goldenrod (Solidago)

Goldenrod (Solidago) shows its fluffy, delicate seed head, awaiting a gust of wind to spread its fine seeds.

Queen Anne's Lace (Daucus carota) seed head

Queen Anne’s lace (Daucus carota) also decorated the sandy edges of the thickets.

Dusty Miller (Artemesia stelleriana) in dunesDusty Miller (Artemesia stelleriana)

Closer to the water, I was surprised to find a familiar plant that I frequently use in gardens and windowboxes. Dusty Miller (Artemesia stelleriana) has delicate white foliage. It is tomentose–covered with fine, matted hairs–giving it a felt-like look and feel. For something so fragile looking, this plant is hardy to -15 degrees C. It is also deer, fire and salt tolerant, adding to its horticultural value.

American Beachgrass (Ammophila breviligulata)

American beachgrass (Ammophila breviligulata) is an ecologically important plant in New England and one that many beachgoers will recognize fondly.

With its rapidly spreading rhizomes,  beachgrass is essential for the building of stable dunes in coastal regions. This species thrives in the harsh, salty conditions at the edge of the shore. As a xerophyte, it has a number of evolutionary adaptations that allow it to survive in extreme conditions. To avoid desiccating winds and heat, its leaves can fold and roll to orient stomata (gas exchange openings) away from the direction of the wind. Beachgrass is a truly dynamic species, able to cope with growing conditions unsuitable for most plants.

Undisturbed by animals, the sand in this image shows the mechanical trace of both wind and grass, creating a natural interference pattern.

American Horseshoe Crab (Limulus polyphemus) shell

Most New Englanders will also recognize the shell of the American horseshoe crab (Limulus polyphemus), an ancient creature more closely related to spiders and ticks than to crustaceans. This beloved animal is well-used in medical research, particularly for a number of unique compounds in its blood that serve as clotting factors and antibiotics. Its fierce looking underside and spiny tail often deter beachgoers from interacting with this animal–however, it is completely harmless to humans. Flipping an overturned horseshoe crab will help its chances of survival, and is a relatively pain-free way of earning good karma.

Common Sand Dollar (Echinarachnius parma)

Another familiar sight to the New England beachgoer is the skeletal remains of the common sand dollar (Echinarachnius parma). Characterized morphologically by its radial symmetry, the echinoderm phylum includes sea urchins, sea cucumbers, and sea stars. A live sand dollar is covered with short maroon spines that allow the animal to move through sand. Its calcium carbonate skeleton, called a test, is often found in a sun bleached state, and has become the subject of various folklore.

Acorn Barnacle (Semibalanus balanoides) on a buoy fragment

The acorn barnacle (Semibalanus balanoides), when submerged, will project its feather-like appendages in search of zooplankton. We mostly recognize these curmudgeonly creatures in their above-surface state, as sharp lumps to be wary of while walking barefoot–but underwater, in their element, these animals are strange and graceful. These were attached to a bit of styrofoam from an old buoy. I wonder how far they traveled.


It’s hard to miss the towering driftwood sculptures that line the beaches near the south end of Plum Island. Haunting in the midday sun, they stand silently as monuments to the human compulsion to build. Many are adorned with bits of net, trinkets, and feathers. I spent a long time photographing them but could hardly do justice.


On the opposite side of the island, the Great Marsh extends towards the Merrimack river. This saltwater marsh is home to a variety of bird species, with a crowd of birdwatching enthusiasts in tow. We saw geese and ducks by the hundreds.

Filled with sedges and salt-marsh hay, the marsh becomes almost completely covered during high tide. Great tracts of hay had been cut down, possibly for ecological purposes, or maybe for horticultural use.

Common Reed (Phragmites)

The ever-present common reed (Phragmites) has outcompeted the cattails that once filled the Great Marsh and lined the island road.

Oriental Bittersweet (Celastrus orbiculatus) berries

Speaking of competition, we found an abundance of oriental bittersweet (Celastrus orbiculatus) growing up and over the black cherries and beach plums. I am constantly amazed with the range of conditions in which this plant can thrive.

Common Winterberry (Ilex verticillata) thicket Common Winterberry (Ilex verticillata) berries

Another stunning plant that we were more pleased to find in abundance is common winterberry (Ilex verticillata). Large winterberry shrubs are scattered among the island, especially near the roadside, and provide ample food for birds this time of year with their bright berries.

Deer Tick (Ixodes scapularis)

We had planned on gathering some winterberry or bittersweet for holiday decorating, until I noticed a tiny friend that had hitched a ride on the arm of my jacket. Ixodes scapularis, commonly known as the deer tick, is the most common vector of Lyme disease. As a warning to those of you who venture outdoors, ticks are still out in full force with the beautiful weather we’ve been having, so remain vigilant!

Speckled Alder (Alnus incana) thicket

A thicket of speckled alder (Alnus incana) by the roadside was filled with chattering birds.

Speckled Alder (Alnus incana) fruit

Alder is in the birch family and shares many common anatomical features, such as these cone-like fruits, with a minute seed released from each individual scale.

Speckled Alder (Alnus incana) male catkins

Its pendulous male sex organs, called catkins, form during the growing season, and will overwinter before opening early in spring to release their pollen.

Alas! we were unable to find a beach plum with any foliage or fruit remaining.. But overall, it was a successful trip nonetheless and we plan on returning throughout the coming year to see the island in bloom.

Until then, thanks for reading.




Some additional photos from the day:


One thought on “In Search of the Beach Plum

  1. Garima Parakh

    I enjoyed reading your article very much. I am a New England artist and currently painting some scenes of Plum Island from my visit in November last year. Great information about the various shrubs and grasses growing in this beautiful region.



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