In general, I tend to favor native trees and plants, fellow organisms which evolved nearby. I hasten to add that my ancestors didn’t evolve anywhere near here; I assume that my DNA originated on another continent, but I enjoy the company of true natives wherever I might be.
When I’m living in a town I like to see the native plants which have managed to endure human occupation, but I also like to see the alien plants and trees which have managed to gain a foothold (roothold?). These are opportunistic plants which have found niches in the human-centered landscape, nooks and crannies where they thrive.
Here in the high desert environment of Bisbee, Arizona, a tree or plant has to be able to handle months without rain. Scattered throughout the town can be found various native trees which are accustomed to such environmental duress. The Desert Willow, a native hackberry, and the Arizona Cypress thrive here without irrigation. There are a few Arizona Sycamores downtown, but they need a bit of watering, as their native habitat is along the few Arizona rivers.
Most of the trees in Bisbee are aliens. The stinky and vigorous Ailanthus trees are common along lanes and alleys, as they are in most towns in this country. Bisbee residents call them Cancer Trees.
Another common alien tree comes from Asia; its native range is broad, all the way from India to China. The Chinaberry tree (Melia azedarach) is a member of the Mahogany Family. Most members of that family favor wet tropical environments, but the Chinaberry thrives here. This summer I’ve seen examples of the species every day, and I’ve watered a young Chinaberry in the yard:
The leaves are large and compound, and they have a glossy sheen which is rare in this desert environment. I’ve grown to appreciate those leaves, a welcome addition to the typical small gray-green leaves of the native trees and shrubs:
The Chinaberry tree bears small berries which are poisonous to humans but not to birds:
So here we have an alien tree which reproduces on its own in this harsh region, but doesn’t become a pest like the Ailanthus. The tree feeds the birds and contributes another texture to the built-up town landscape.