The trees common to Loudoun are four varieties of the white oak, i. e., common, swamp, box, and chestnut-leaved, the latter, however, appearing only along the margin of the Potomac River; black, Spanish, and red oak, chestnut oak, peach or willow oak, pin oak; and in the eastern parts of the county, black jack, or barren oak, and dwarf oak, hickory, black and white walnut, white and yellow poplar, chestnut, locust, ash, sycamore, wild cherry, red flowering maple, gum, sassafras, persimmon, dogwood, red and slippery elm, black and white mulberry, aspin (rare), beech, birch, linn, honey-locust, sugar maple, sugar nut, yellow and white pine, hemlock, and red cedar.

Among the smaller trees and shrubs are the white thorn, maple-leaved or Virginia thorn (suitable for hedging), hawthorn, wild May cherry, or service berry, water beech, fringe tree, red bud, black alder, common alder, sumach, elder, laurel, witch-hazel, hazel-nut, papaw, chinkapin, burnish bush, nine bark, button-bush, honeysuckle, several varieties of the whortleberry or huckleberry, and wild gooseberry.

A few of the brambles met with are the greenbrier, high blackberry, dewberry, or low blackberry, and raspberry.

A list of the vines and creepers would comprise the fox grape, three varieties; pigeon, or raccoon grape, chicken grape, a wild bitter grape, sarsaparilla, yellow parilla, poison-vine, or poison-oak, clematis, trumpet-flower, and wild potato vine.

The medicinal herbs found in Loudoun are the rattlesnake root, Seneca snakeroot (also called Virginia snakeroot), many varieties of mint, liverwort, red-root, May apple, butterfly-weed, milk weed, thorough-stem, trumpet-weed, Indian-physic, lobelia inflata, and lobelia cardinalis, golden-rod, skunk-cabbage, frost-weed, hoar-hound, and catnip.

The injurious plants with which the careful farmer must contend are the wild garlic, tribby weed, dog fennel, two varieties of the common daisy, oxeye daisy, St. John’s wort, blue thistle, common thistle, pigeon-weed, burdock, broad and narrow-leaved dock, poke-weed, clot-bur, three-thorned bur, supposed to have been introduced from Spain by the Merino sheep, Jamestown or “jimson” weed, sorrel, and, in favorable seasons, a heavy growth of lambs quarter and rag-weed.

Of introduced grasses, Loudoun has red clover, timothy, herd’s-grass, orchard-grass, and Lucerne to which last little attention is now given.  Native grasses are the white clover, spear grass, blue grass, fox-tail and crab grass, the two last-named being summer or annual grasses.  Several varieties of swamp or marsh grass flourish under certain conditions, but soon disappear with proper drainage and tillage.

Although some of the wild flowers of Loudoun merit the attention of the florist, as a whole they have no commercial value or significance and, for this reason, an enumeration of the many varieties has not been thought expedient.