Some of my favorite stretches of rural gravel roads are those which wind through bottomland woods. Yesterday I noticed to my surprise a limestone cliff along such a road. I’d been driving past the cliff for weeks and it had never caught my eye.
I had to pee anyway, so I pulled over into a patch of shade and got out of the car to investigate. The cliff was about twenty-five feet high and a dark Eastern Red Cedar clung dourly to the clifftop. A jumble of flat limestone scree was heaped against the base of the cliff; the base of the cliff had been cut back to provide room for the road and the scree was the resultant debris. Several plants were growing right out of the heaped limestone fragments, enjoying the lack of competition and the window to sunlight provided by the road.
A yellow wood sorrel plant was flourishing in the intermittent dappled sun. This is a native plant, Oxalis stricta to botanists; the species has modest yellow flowers and distinctive lobed leaves:
I also found a mint-family species growing from the talus. The square stems and aromatic opposite leaves were diagnostic. The clump of plants was almost finished with blooming but a few small violet flowers remained. I tried to pick a shoot to take home but an entire plant, roots and all, ended up in my hands. I didn’t mean to do this — I wrapped the roots in a wetted bandanna and threw the plant onto the back seat of the car. The plant is now on my kitchen counter with its roots in a plastic water glass.
I’ve tentatively identified the plant as Blue Giant Hyssop, Agastache foeniculum, a native species new to me, although I’ve seen photos of it. The leaves have a distinct anise odor with musky overtones.
The brief stop got me to thinking about the resemblance between river- and creek-side habitats and roadside habitats. For a plant species which requires a certain amount of sunlight these habitats serve as a refuge, an escape from the tyranny of shade cast by trees, shrubs, and other competitive species. Such habitats tend to be periodically disturbed by flooding or road-graders. A species which has evolved to spring back from such intrusive events will gravitate to such niches and flourish.