There are places in nature that feel special in some way, places we find ourselves returning to. One special place for me is a bluff in the lower valley of Ellerbe Creek--a stream in Durham, NC for which I founded a watershed association a quarter century ago.
During a recent visit, I took a walk with naturalist Cynthie Kulstad in one of the preserves we created back then, 80 acres called Glennstone Preserve. Cynthie is the botanist/horticulturist who helped sustain many of the plantings I had nurtured in parks and nature preserves while living there. The trails and our inclinations led us down to this special spot, on adjoining Army Corps of Engineers land.Crowned by a massive white oak, the bluff is a collection of diabase boulders and uncommon plants overlooking the creek.
One of those uncommon plants that makes this spot distinctive is resurrection fern (Pleopeltis polypodioides), all curled up and dried out on one of the boulders. Resurrection fern is an epiphyte, meaning it builds itself largely out of water and air, pluse whatever few nutrients collect on the rock it clings to from fallen leaves. Unlike most plants, this fern's leaves can dry out during droughts, then rapidly rehydrate after rains.Looking up, I spotted another unusual native plant, eastern mistletoe (Phoradendron leucarpum), growing high on a tree branch. This one's a hemiparasite, meaning it extracts some sustenance from the tree but also has green leaves to make some of its own energy.
Other trees nearby also had dense balls of vegetation high up in the branches, but they weren't mistletoe. Those are witch's broom--a dense cluster of twiggy growth that is the tree's response to a pathogen or other irritant. Cynthie pointed out they are common on hop-hornbeam, a tree I hadn't seen in a long time and had been wanting to run into.
Turned out we were in the midst of a grove of eastern hop-hornbeam (Ostrya virginiana), growing along the edge of the bluff. (Upon returning to Princeton, I found some of these with their distinctive bark growing in Autumn Hill Reservation.)
It would be interesting to know if pine needles, like those high up on this shortleaf pine, also vary according to how much sun they receive."If there is some sunlight however, even a little diffuse light (see below), then a tree makes the most of it by producing shade leaves lower down in its canopy. Shade leaves are larger and thinner than normal sun leaves, and often appear a darker green (they contain more chlorophyll). They also have half as many stomata than sun leaves, or even fewer, and so have a lower respiration rate. They can react quickly to brief bursts of sunlight and dappled shade.
Shade leaves can turn into sun leaves and visa versa; providing that the change is gradual. This is something that a gardener moving a plant outside that has been grown indoors or in the greenhouse, must be aware of. When a plant is taken outdoors, place it first under shade and gradually over several days increase its exposure to bright sunlight."