The Natives, the Exotics, the Benign Visitors
Flora and fauna have worked out a generally successful partnership over the ages: Scatter and fertilize my seed, and I’ll feed you and give you cover. It’s not the fault of those cooperating creatures that some seed does not belong where it’s found these days, growing into vines, grasses, herbaceous and woody perennials that usurp the natives’ rightful place faster than you can say or Maiden Grass. Buddleia davidii and Miscanthus sinensis seem such lovely, guileless Asian transplants! Maybe Buddleia and Miscanthus are not the best examples of fauna-assisted invasion. Each drops its seed or has its seed blown by the wind; each germinates and grows with very little need of fertilizer (think guano or scat). They’re just the first two exotic invasives that come to mind for me, a gardener guilty in earlier years of growing both, from seed–even of sharing both with fellow gardeners.
Japanese Bayberry, Berberis thunbergii, is probably a better example. Mockingbirds and dapper cedar waxwings feast on its rich, oily, bright red berries and then fulfill the scattering-fertilizing pact. It’s always interesting to me that birds with their delicate little feet can perch in a sharp-thorned shrub like barberry and remain unscathed. Preying mantis find thorny shrubs hospitable too. In the spring I’ll discover a half-dozen sticky egg cases nestled in the elbows of rose branches, and the barberry that I laboriously eradicated was the Hostess with the Mostest.
I enjoy watching goldfinches in the cold months feeding on my native grasses, especially switch grass, Panicum virgatum, both for the satisfaction of knowing that they’re good plants and for the pleasure of the show. The goldfinches make their bounding flight through the garden and light their featherweight selves on the Panicum seed heads, bowing the seven-foot stalks nearly to the ground. In a moment’s nibble, they’re off, and the stalks rise up again. The show might continue longer if it weren’t for the steel mesh feeder hanging from an arbor within close viewing range of our kitchen windows. In the feeder is goldfinch candy, Guizotia abyssinica, niger seed. This “thistle” is a healthy South African snack and one that, thanks to heat treatment, will not grow into anything in the garden or elsewhere.