Range: Throughout the United States and southern British America. Habitat: Moist soil; twining over fences and thickets or trailing on the ground.
A very conspicuous weed, especially when in fruit, capable of spreading itself over a square rod or so of ground, when not finding other support. Stems very slender, pale green, faintly ridged and slightly roughened on the ridges, three to twenty feet in length; several such stems strike off in all directions from the deep-boring, branching, perennial root. Leaves halberd-shaped, the tips and the basal auricles rather long-pointed, smooth but with edges slightly roughened; petioles long and nearly as thick as the stem from which they spring; sheath smooth, oblique, slightly rough on the ridges. Flowers yellowish green, in slender, axillary racemes, interrupted and leafy, two to four inches long; calyx five-parted, the three outer segments winged and decurrent on the pedicels. Achenes small, three-angled, obtuse at both ends, jet black, smooth and shining. They are persistent on the stems until cold weather and birds glean them, which accounts for the presence of the weed along fences and thickets. (Fig. 63.)
The best remedy is hand-pulling when the ground is soft, early in the first season's growth, before the root has extensively grown. Otherwise cut the vines from the roots while in early flower, using salt or kerosene on the shorn surfaces. Vines like this are an argument against any more fences than are absolutely necessary.