The scrub or bear oak (Quercus ilicifolia) will forever be associated in my mind with the Hudson Highlands, specifically the peaks of the Hudson Highlands. These are small mountains, most of them 1,000 to 1,500 feet above sea level (although it must be said that because the Hudson River is at sea level, you see the entire mountain, as it were). Nonetheless, many of them are topped by “balds,” expanses of bare metamorphic rock that sometimes cover half an acre or more. The edges of these balds are inevitably ringed by thickets of scrub oak.
Scrub oak is so called because it rarely reaches heights greater than 15 feet. Its other name “bear oak” reputed refers to the fact that only bears eat its bitter acorns. (This is not actually so, as deer and turkeys also feed on the acorns.) Finally, its trivial name ilicifolia means “holly-leaved.” Indeed, like all oak leaves Q. ilicifolia leaves have a waxy coating that makes them resemble hollies. In addition the general shape, only faintly lobate and with the ends of the lobes tipped with small bristles, recalls Ilex as well.
The scrub oak is associated with areas that have been burnt. It is one of the first woody trees to colonize such places. I suspect that the balds on top of the Highlands were caused by fires. That is definitely the case on Mount Desert Island in Maine, where a famous fire of the late 1940s burnt thousands of acres, denuding the mountain tops, which were then quickly eroded down to bare rock. Scrub oak is found there too.
I have delightful memories of approaching the summits of various Highland mountains and knowing that we were near the top because we began to encounter the scrub oak, which is found nowhere else in the forest. On warm sunny days you would inevitably hear a lot of slithering, thumping, and thrashing of dry leaves as the myriad snakes that had been sunning themselves in the branches of the oaks dropped to the ground and headed for cover. If you moved quickly, you could see the last of them making for the undersides of the ledges. If you moved especially quietly you could also manage to come up on a few snakes still draped in the branches.
The scrub oak is gnarled in its habit, its branches twisted in spaces as if it had grown around something complex that had since disappeared. The bark is gray and eventually furrowed or platy like the larger oak species. The leaves are dark green above and light green below. In its cragginess and muted coloration it seems suited to the marginal habitats where it tends to be found.
In addition to mountain tops, it is also found on pine barrens, where fires are frequent, and scrublands along the coast and on coastal islands, where the stresses include wind and salt, as well as fire. Scrub oaks have very deep taproots, so they survive fire not be failing to burn (like sequoias), but through their ability to regenerate a new canopy from their roots.
In areas where fires are less frequent or conditions are less marginal, scrub oak is an early successional plant and is eventually overtopped by pines and taller oaks. But the trees growing at the tops of the Hudson Highlands have likely been there for decades; they are growing right at the edge of bare rock and it will take some time before enough soil builds up to allow anything else to take hold. The geological record of the Highlands is full of charcoal that denotes repeated fires, with peaks of oak pollen directly above them. Historically fires were started by lightning and by the tribal people. And fires are still common in the areas today.