"Sandy Hook" beach and dune plants- Arenaria, Amaranth, Ammophila, Solidago, Xanthium, Cakile, Andropogon, Panicum, Rhus, Lepidium - Brookdale College Ocean Institute, Dave Grant, Sandy Hook, NJ

Sandy Hook's Dune Plants
Dunes are Sandy Hook's first line of defense against storm waves.
They are also a reservoir for sand that is released back to the beach during and after storms.

Sandwort (Arenaria) survives in undisturbed areas where it isn't trampled.

(Left) Dunes get their start when seeds of pioneer plants like sea rocket (Cakile edentula) are carried from neighboring beaches by wind and waves. If these and other plants like the "sand-loving" dune grass (Ammophila) are not trampled by human activities, they spread across the beach and trap sand, especially during winter wind storms. (Below, left)
To read more about beach seeds and dune plants, click here.

(Above) Foot traffic and vehicular activity cuts the rhizomes (Underground stems) of dune grass, which is its primary method of spreading (Vegetative reproduction). When too much of this type of disturbance occurs, the dune could stop growing and might even begin to erode.

(Left) An exceptionally long rhizome is exposed by winter winds and dutifully reburied by helpful students from the Ocean Institute.

(Left) Dune grass and other plants at the beach have light seeds that can be moved to other beaches by the wind, waves and currents. They are also an important food source for wintering birds like sparrows and snow buntings. (Below)

South of New Jersey, Delaware and Maryland, other dune plants like sea oats are the most important dune building plants.

Dune plants must have mechanisms to deal with drought and drying winds and salt spray. Dune grass simply curls up to close its leaf pores. It will open up a few hours after it is exposed to freshwater from rain or fog (Right).

Cross section of Ammophila leaf.

The rare sandwort (Arenaria) has succulent stems and leaves to retain water, and small inconspicuous flowers.

All of these plants tend to trap sand when it is moved by the wind and start the dune building process.

The height of the dune ridge and the protection provided from wind and salt spray determines the height and variety of plants growing behind the dunes. Note the salt spray horizon of the tree tops on the left

The chloride ions in salt spray are toxic to plants. The wind also causes excessive drying of the leaves, sand-blasting and physical damage to the branches. One math-related activity you can try at the shore is measuring the angle of the salt-spray horizon of the trees.

The Back-Dune areas

On the landward side of the dunes and in the lee of the storm winds, less rugged plants can survive. The beach plum (Prunus maritima) provides food for nectar eating insects, the birds that feed on them in the spring, and animals (including people) who feed on the fruit in the fall. Need a recipe for beach plum jam? Check here on our recipes page.

(Below) You can also use the recipe to make prickly pear jam from the Indian pears on cactus (Opuntia), but always use garden gloves or bring tape to remove spines...just in case!

(Below) The cactus look spineless but are covered with tiny spicules that can irritate the skin. Don't disturb them and do make sure your students do not inadvertently trample the plants.

Students examining the fruit and seeds.

Wrinkles in the cactus stem allow it to expand and soak up moisture when it is available. The tough "skin" protects the plant from drying out and the clusters of spicules keep animals from grazing on the plant and fruit. Box turtles are one of the few animals that feed on prickly pear cactus.

Other important plants like the goldenrod (Solidago) spread by wind-blown seeds and since they are fall bloomers, are important food for fall migrants like the monarch butterfly.

(Right and below) Note the resemblance to dandelion seeds. Goldenrod and dandelions are in the same plant family, the Composites. These sail in the wind to new growing sites.

Goldenrod flowers and seeds in the fall. Like
dandelions, the seeds are spread by the wind.

Cockleburs (Xanthium) hitch-hike to new areas with the help of animals (And people) that become entangled in their seed pods.

The seeds of several plants like the tick-weed often get stuck to visitor's socks.

The dreaded sand-burs (Cenchrus) are also dependent on animal movements to distribute their seeds (This is one of several good reasons to wear shoes or sandals at the beach).

Where the sand is stabilised and dune grass loses its vigor because it is not being buried by drifting sand, other grasses like the bluestem grass (Above) or switch grass (Andropogon) and (Right) broom grass (Panicum) take over.

Poison ivy shrubs (Rhus) are quite common on Sandy Hook, especially behind the sand dunes. Besides being rugged, it also has fruit that about fifty-five species of birds eat and spread.

(Above) Birds also feed on the tiny seeds of poor-man's pepper (Lepidium), a mustard; or rabbit's foot clover (Trifolium), a Legume. (Right)

A popular activity in our botany lesson is studying botany through artwork and plant pressing herbarium specimens. All of the plant species at the shore are important for holding the sand in place and providing food and shelter for wildlife. Do not pick flowers or disturb any plants. If you have questions, ask the naturalists at the Visitor Center.

Ken Rice 10-72

Root nodules of bayberry harbor nitrogen-fixing bacteria that help the plant grow in poor sandy soils.

Beach Amaranth is a new addition to Sandy Hook's plant list. Thought to be exterminated from NJ long ago, it reappeared after beach renourishment activities in the 1990's.

"Physicists, chemists, biologists and even mathematicians represent in the public mind the potential to do good - or great evil. But you don't expect botanists to win the Nobel Prize and...
you don't expect them to destroy the world one day." (Karl Sabbagh - A Rum Affair)