A Dune Garden at Sandy Hook

There is an observation deck over the pavillion at the North Beach at Sandy Hook, and the view of Manhattan is spectacular.

Turn around. That's the Sandy Hook lighthouse gleaming over the treeline of one of the largest maritime forests in NJ. The lighthouse was only 500 feet from the shoreline when it was built in 1764; now it's about a mile and half away.

It's hard to believe all that land came from grains of sand that washed up the coast from Manasquan, blew onshore, and was trapped by tiny plants then bigger ones as it gradually built up into a dune.

Later, you can read about Littoral Drift, the Nearshore, Foreshore, and Backshore zones of the beach, and Primary and Secondary dunes; this blog is about the plants. The NPS built a boardwalk from the deck so you can walk down through the dunes and take a look at them on your way to the beach.

1. The Classics

American Beachgrass (Ammophila breviligulata)

Beachgrass is a pioneer species that promotes the continual growth of the dunes because it grows back after it's been buried by sand. Its roots (rhizomes) trap and stabilize sand (the roots are exposed at the bottom of the picture on the right). It's highly resistant to salt spray, but is vulnerable to trampling. It is commonly used when planting dune grass for Coastal resiliency.

Asiatic Sand Sedge (Carex kobomugi)

This invasive nemesis of American Beachgrass out-competes it by forming a monoculture that is less damaged by trampling. There is some evidence it may be effective at preventing erosion during large storms like Superstorm Sandy. The “large, club-shaped flowerhead and broad, strongly recurved leaves are distinctive”. The picture on the right was taken in January.

Seaside Goldenrod (Solidago sempervirens)

This flower starts lighting up Sandy Hook in late summer and attracts migrating Monarch butterflies during the fall. It prefers sandy, salty soil and has fleshy leaves for storing water. Its heavy pollen doesn't cause hay fever. The middle picture was taken at Horseshoe Cove at Sandy Hook, and the picture on the right was taken in April of a sprout growing by a dead goldenrod, probably from a shared “short, stocky”rhizome.

Beach Plum (Prunus maritima)

The beach plum is native to the northeast coast from Newfoundland to North Carolina, with most found from northern Massachusetts to southern NJ. Because it is salt tolerant and deep rooted, it is one of the dominant shrubs on coastal dunes. In spring it produces showy white blossoms so prominent they can be tracked with arial surveys. Berries ripen red and purple and can be harvested for jams in the late summer and fall. Henry Hudson noted the thickets of blue plums along the banks of the Hudson River in 1609 that Giovanni de Verrazano had called “damsel trees” in 1524. From left to right the pictures show early spring flowers, unripened berries and egg-shaped (ovate) leaves, ripening berries, and withered winter berries. (A picture of a beach plum is also at the beginning of this post.)

Northern Bayberry (Morella pensylvanica)

This other prominent coastal dune shrub looks a little like the beach plum at first. The bayberry has an oblong (specifically oblanceolate, oblong, obovate) leaf shape that is narrower than the more egg-shaped (ovate or obovate) leaf of the beach plum. (It has yellow resin dots on the underside of the leaf, while the southern variety, the wax myrtle, has them on both sides.) The fragrant wax from the bayberry fruit is used to make candles. The blue-grey fruit is at the bottom of the picture on the left.

Eastern Prickly-pear (Opuntia humifusa)

The only native cactus in NJ. By June its yellow flowers gleam throughout the Park's scrub and waysides, briefly, then are replaced with a red fleshy fruit. Its flat, bristly stems are called paddles, and are “used in the South in breakfast omelets”. Hmm.

Eastern Redcedar (Juniperus virginiana)

This conifer is common to coastal dunes, as well as being a pioneer species of disturbed ground. Prickly needle-shaped leaves on young plants become overlapping scales on mature trees that provide shelter for birds. The color of its waxy fruit changes from pale-green to dark blue by mid fall. The berries are an important source of food for birds during the winter (it is where the cedar waxwing, which is common to Sandy Hook, gets its name). Redcedars were used by colonists to flavor gin; gin is either from the "French genièvre or the Dutch jenever, which both mean juniper”. The Army used to guard the redcedar and holly trees from being chopped down for Christmas decorations. The picture on the right, taken during a ranger-led walk through the Holly Forest, shows why this juniper is mistakenly called a cedar.

2. Deeper Dive

Little Bluestem (Schizachyrium scoparium)

A very common field weed . The distinctive, fluffy white seed heads start blooming in mid summer and continue through the fall. Seed heads are purple when emerging. Very similar to Broomsedge bluestem (Andropogon virginicus) except:

“Little Bluestem has flower or seed stalks that extend out beyond any leaves on the stem. [ Andropogon virginicus] flowerheads or seedstalks are tucked into enclosing leafy bracts. In the non-seeding seasons, Little Bluestem can often be identified by plucking off a central stem at the base, at the soil level. Little Bluestem stem bases tend to be reddish, while [Andropogon virginicus] stem bases are white.”

And it's also similar to Coast Beard-grass (Schizachyrium littorale)! (Grass identification can be a heavy lift.)

Beach Wormwood (Artemisia campestris ssp. caudata)

Sandy Hook has the largest known population of this state-listed plant in NJ (S2 - Imperiled), according to a 2012 report by the NJDEP. The second largest is also in Monmouth County, in the dunes west of the Keansburg boardwalk. In the picture on the left, you can see the two distinctly different-looking growth stages. It begins with narrowly oblong basal leaves, and matures into "paniculiform arrays" of flowerheads (this website has pictures of both stages as well). The picture on the right was taken in January at the sand fence near the beginning of the beach path from the pavilion. Another species of wormwood, Artemisia absinthium, is used as an ingredient in absinthe, bitters, and vermouth. 

Winged Pigweed (Cycloloma atriplicifolium)

That name. Pigweed can mean several members of the Amaranthus family that were used as pig fodder. “Surrounding each group of sepals and the seed, there is a pale membranous wing (wider than 0.5 mm.) that is circular and slightly fringed along its outer margin.” The wings are the dots along the stems in the picture on the left. The picture on the right is an alien landscape of pigweed covering a dune next to Waackaack Creek in Keansburg. Pigweed becomes a tumbleweed when it dries up in the fall.

Common Milkweed (Asclepias syriaca)

Several have been planted in a corner near the end of the wooden ramp. Monarch butterfly populations have declined by 90% in the last 20 years, so the National Wildlife Federation has been promoting milkweed-planting throughout the monarch's migratory paths, that include Sandy Hook. Monarchs will only lay their oval, off-white eggs (scroll down) on the underside of the milkweed leaf. The picture on the right is of the seed husks in January. Last summer there was a single orange Butterfly Milkweed (Asclepias tuberosa) blooming in the scrub on the bayside dune across from Parking Lot A (just past the toll-booths at the entrance).

Common Evening-Primrose (Oenothera biennis)

Common and widespread, flowering from June to October. It has four yellow petals and a distinctive seed pod that turns woody on larger plants in the winter. Seeds contain gamma linolenic acid, an anti-inflammatory compound. In its first year this biennial typically produces a leafy basal rosette with a white mid-vein but no flowers. That's the picture on the left. The two on the right were taken in January at the sand fence near the beginning of the beach path from the pavilion.

Sandspur (Cenchrus sp.)

Stickers. “Nature's hitchhikers”. Two species common to both the primary and secondary dunes are Dune Sandspur (Cenchrus tribuloides) and Mat Sandspur (Cenchrus longispinus). Here's how to tell the difference: tribuloides is hairier between the spines, and has less than 43 spines; longispinus has 45 or more (enjoy!). The picture on the right was taken in January. There are some nice off-season pictures on the Maryland Biodiversity Project (MBP) website of tribuloides and longispinus.

These pictures – and over 6 million observations worldwide - have been geolocated and posted at iNaturalist.org. You can zoom-in to Horseshoe Cove to see a map of icons representing groups of species, like plants, birds, fish, shells, etc.

A great website for identifying plants in maritime habitats like Sandy Hook is “Cape May Plants – An Identification Guide” by CapeMayWildlife (most of the plant names are linked to it). Another site, “NY-NJ-CT Botany Online” has biota lists for many of the parks in our area, including a plant list for Sandy Hook.