Sometimes western poison-oak attaches itself to upright objects for support and takes more or less the form of a vine. A plant of this type is shown in figure 13, where it is growing on a telephone pole by the roadside. It may be noted even in this case that the tendency is for individual branches to continue an upright growth rather than become entirely dependent upon other objects for support. In some areas, especially in woodland, poison-oak may grow principally as a vine. Areas have been noted where 70 to 80 percent of the trees leaves and flowers. in a wooded area support vines running more than 25 or 30 feet in height, although the most common form of the plant is the shrub. _Figure 13._--Western poison-oak on a telephone pole. This vine form is not uncommon, especially on trees in woods. _Figure 14._--Western poison-oak: Upright shrub, with fruit, growing in open pasture field. _Figure 15._--Western poison-oak, showing common leaf types: _A_, The more common leaves with irregular margins; _B_, less typical, although not uncommon, leaves with even margins. _Figure 16._--Western poison-oak growing alongside roadside. This rank shrubby growth is typical for most localities. _Figure 17._--Western poison-oak, showing common leaf types: _A_, Leaves with thick leathery appearance; _B_, leaves irregular in shape with much-curled or distorted surfaces; _C_, branch, with leaves and flowers. In open pasture fields western poison-oak usually grows in spreading clumps from a few feet to several feet tall (figs. 14 and 16). Where it develops extensively it greatly reduces the area for grazing and becomes a serious menace to most people who frequent the area or attend cattle that come in contact with the plants while grazing. _Figure 18._--Western poison-oak: _A_, Top of shrub, with leaves and fruit; _B_, clusters of fruit after leaves have fallen. Low-growing plants, especially those exposed to full sunlight, are often quite woody and show no tendency for vining. Low-growing plants with woody stems are common in pasture areas or along roadsides. Livestock in grazing do not invade the poison-ivy shrub, and as a rule these plants continue to spread both by root-stock and seed.