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. FAUNA.--Wild ducks, geese, and turkeys, pheasants (English and Mongolian), partridges and woodcock are among the game fowls of Loudoun, and eagles, crows, buzzards, owls, and hawks among the predatory. The usual list of songbirds frequent this region in great numbers and receive some protection under the stringent fish and game laws in force here. Red and gray foxes, raccoons, opossums, woodchucks, squirrels, hares and smaller animals are quite general. In pioneer days the county abounded in the larger species of game common to the forests of North America. Among these were the beaver and otter, buffalo, deer, wolf, wild-cat, panther, bear, fox, and elk or wapiti (_Cervus canadensis_), noble herds of which ranged the mountain sides and valleys of this section. TRANSPORTATION FACILITIES.[13] Good roads, always of immeasurable importance to the farmer, were early made necessary by the tremendous crops of marketable products harvested from Loudoun lands. Though this need, in time, became imperative the roads were never hastily and imperfectly constructed; they were built with an eye single to permanence and with due allowance for generations of unintermittent and augmentative traffic. These roads yielded their promoters modest dividends, but with the completion in 1832 of the Chesapeake and Ohio Canal, bordering the county just across the Potomac, transportation to and from Washington (Georgetown) and Alexandria was materially cheapened and the earnings of the turnpike companies suffered a corresponding decrease, the income, in many cases, being barely sufficient to defray the expense of maintenance. Tolls are now collected at only two points, in the County.