New Jersey is a paradoxical state. It’s the most densely populated state in the United States, and it’s hardly the first place people think of for natural areas. However, New Jersey is among the top states in the nation in terms of the percentage of land protected from development. That status is thanks largely to the pine barrens in southeastern New Jersey, which is recognized as worthy of protection by both federal and state governments.
Why is the pine barrens so special? To residents of nearby cities, it’s an accessible wild area. To naturalists, it’s a unique habitat with many rare plant species, including one now found nowhere else. To gardeners like ourselves, it’s a place with really cool plants.
To explain what the pine barrens is, first let me explain the setting. The southeastern half of New Jersey is in the Atlantic coastal plain, the zone of low, relatively flat land along the coast from Long Island to Florida. The Atlantic coastal plain, in general, is characterized by sandy and gravelly soils, typically acidic and low in nutrients. The soil is particularly so in the New Jersey pine barrens.
The sandy character of the soil means that it retains very little water. Instead, that soil acts as a filter, purifying water before it collects in a huge aquifer underlying the pine barrens. This aquifer explains, in part, why the region is protected from development. In the 1870s a Philadelphia industrialist was scheming to tap into that aquifer to supply pure drinking water for Philadelphia. In the ensuing outcry, New Jersey banned the export of water from the state. A century later, New Jersey partnered with the federal government to create the Pinelands Reserve, encompassing one-fifth of New Jersey’s acreage, where development is limited.
That sandy soil means that upland areas in the pine barrens are very dry. That, combined with the acidic, nutrient-poor soil, limits the number of trees that can grow. Note that, on the coastal plain, “upland” isn’t very far up. The highest point in the pine barrens is only 208 feet (63 m) above sea level, and a hill of only 121 feet (37 m) was deemed significant enough to be named “Mount Misery.”
The uplands are dominated by pitch pine (Pinus rigida) and oaks, most commonly blackjack oak (Quercus marilandica) and post oak (Quercus stellata). These dry sites are susceptible to fire, and the pitch pine is exquisitely adapted to fire. In a moderately hot fire, a pitch pine may lose its branches but it can sprout new branches from old wood, even directly from the trunk. In a hotter fire, the pine may burn down to the ground but it can regrow from dormant buds at the base of the trunk. A fire that is hotter still may kill the trees outright, but the heat will also induce the cones on nearby trees to open, scattering their seeds just when they have open ground to take advantage of. Where fire is very frequent, the pine trees never have a chance to grow to full size. Entire forests can be under 6 feet (2 meters) tall. It’s quite an experience to be able to look over the top of a pine forest!
Where the upland pine-oak forest is tall enough to have an understory, that’s dominated by huckleberries (Gaylussacia baccata and Gaylussacia frondosa). In some places, black huckleberry forms a uniform carpet under the trees. In more open upland areas, we get some interesting dwarf shrubs. Bearberry (Arctostaphylos uva-ursi) is familiar to many, but do you know broom crowberry (Corema conradii)? This rare plant, a cousin of Empetrum, has deep green, needle-like foliage and a habit reminiscent of heath. A more common plant in this habitat is goldenheather (Hudsonia ericoides). Despite the common name, it is not in the same family as heather, but rather in the rockrose family (Cistaceae). In spring, goldenheather is graced by flowers of an unbelievably bright yellow. Here and there we find flowers of pink lady’s slipper (Cypripedium acaule). A rather strange sight in spring is the flowers of ipecac spurge (Euphorbia ipecacuanhae). Before any leaves emerge, naked stalks are topped by pale green inflorescences, looking like something designed for a sci-fi movie. I’ve never heard of anyone gardening with ipecac spurge, but some forms have attractive foliage, and the plant stays compact enough for a rock garden.
In the upland forest in spring, we get to enjoy the huckleberries in bloom, but this can become monotonous. So let’s look instead at moister areas: the pitch pine lowlands. Here, the surface usually looks dry, but the water table is only a foot (30 cm) or so below, easily accessible to the plants. The pitch pines still dominate, but the understory is more diverse and showier. Here, we find a greater variety of ericaceous shrubs, including highbush blueberry (Vaccinium corymbosum) and a lowbush blueberry (Vaccinium pallidum), as well as lesser-known ericaceous shrubs like staggerbush (Lyonia mariana), fetterbush (Eubotrys racemosa, syn. Leucothoe racemosa). All of these have pretty, white, urn-shaped flowers in spring. Showier is the sand myrtle (Kalmia buxifolia, syn. Leiophyllum buxifolium). This is a small shrub that can be covered with starry white flowers. It’s also an excellent plant for a rock garden if it is given acidic, low-nutrient soil. For rock gardeners, the favorite is usually pixiemoss (Pyxidanthera barbulata), a charming subshrub in the diapensia family. The foliage does resemble moss, and the flowers look a lot like those of its cousin Diapensia. Pixiemoss starts blooming very early—sometimes in February—but fortunately for visitors, its bloom period is quite long, so we are almost sure to find it in bloom in early May.
Let’s move lower still, into the wetlands. Wetlands are where we find the greatest diversity of plant species. Wetlands are also where we find the fun plants—the carnivorous plants. In the acidic, low-nutrient bogs, plants have a hard time getting enough nitrogen. Carnivorous plants have solved that problem by letting the nitrogen find them, in the form of insects that they trap and digest. The carnivorous plant species in the pine barrens consist of one pitcher plant (Sarracenia purpurea), three sundews, and quite a few bladderworts. On the pre-conference trip, preceding the Spring Study Weekend we’ll be able to see all three types.
You’re probably already familiar with pitcher plants (Sarracenia spp.), which trap and digest insects inside leaves modified into the shape of pitchers. But did you know that those liquid-filled pitchers contain an entire food web of organisms? The remains of the trapped insects feed bacteria, which feed protozoa, which feed mites and other tiny invertebrates, which feed fly larvae. Some species of mosquitos lay their eggs almost exclusively inside pitchers. The larvae thrive on nitrogen-rich bacteria and insect remains. When they emerge as adults, they don’t feed on blood because the larvae grew in a nitrogen-rich environment and don’t need extra nitrogen from blood to be able to produce eggs.
In early May, the plants will still have their pitchers from last year, along with fat round flower buds. The new pitchers emerge only after flowering is done; it wouldn’t be adaptive for the plant to eat its own pollinators.
Sundews (Drosera spp.) have leaves covered with hairs, each tipped with a droplet of sticky fluid. That fluid causes the plants to glisten in the sun (hence the common name), and it also traps insects.
The least familiar of the carnivorous plants of the pine barrens are the bladderworts (Utricularia species). These plants, which grow in ponds or wet ground, have feathery leaves dotted with 1/8-inch (3 mm) bladders, which are spring traps. When a tiny invertebrate brushes against trigger hairs near the trap door, the door springs inward, sucking the victim inside. This happens fast: the trap opens and closes in only just two milliseconds. Most bladderworts have rather showy flowers that look something like toadflax (Linaria sp.) flowers, but in spring we will only see the leaves with their bladders.
Another fun plant of wetlands is a fern, but one that doesn’t look remotely ferny. It’s curlygrass fern (Schizaea pusilla). The sterile fronds look like curls of very fine green wire. The fertile fronds look just a bit like the metal ornament on the prow of the gondolas of Venice. The whole fern is so tiny that it’s hard to spot. Most people never find this fern on their own until they are shown what to look for. On the pre-conference trip, we’ll be showing people to a good-sized stand.
A final item on the list of fun wetland plants is golden-club (Orontium aquaticum), a plant in the arum family. Locals give it the charming common name of never-wet because water beads up and rolls right off the leaves. (This is assumed to be an adaption to prevent mud from collecting on the leaves and blocking out the sunlight.) The flowers are—you guessed it—golden and club-shaped. They bloom in spring and are sometimes numerous enough to create a band of gold along the edge of a lake.
The wetlands are also home to numerous orchid species. In spring, the only wetland orchid we might see in bloom is southern twayblade (Neottia bifolia). Compared to a pink lady’s slipper, the southern twayblade is almost comically homely. The flowers are tiny and brownish. It also typically grows in the heavy shade of white cedar swamps, making it still harder to spot. Later in the year, the pine barrens have showy wetland orchids: the pink of rose pogonia (Pogonia ophioglossoides); grass pink (Calopogon tuberosus) and dragon’s mouth (Arethusa bulbosa) in June and the white, yellow, and orange of Platanthera species in July.
The wetlands, like the uplands, are home to some ericaceous shrubs and sub-shrubs, notably cranberry (Vaccinium macrocarpon). This species is the same one grown commercially, and New Jersey is the third largest producer of cranberries in the United States.
The pine barrens, despite its unusual environment, is home to a fair number of horticulturally important species. In addition to the blueberries and cranberry already mentioned are sweet pepperbush (Clethra alnifolia), possumhaw viburnum (Viburnum nudum), red chokeberry (Aronia arbutifolia), American holly (Ilex opaca) and inkberry holly (Ilex glabra). A plant known to rock gardeners is stiff aster (Ionactis linariifolia, syn. Aster linariifolius). Seeing these plants in the wild can be inspirational for the garden, especially if your soil is acidic or if you have wet areas. And if you fall in love with bog plants, you can easily grow many of them in an artificial bog, even in a small container.