http://www.montananaturalist.org/
"The fruit is the easiest way to tell huckleberries from unrelated plants. However, if no fruit is showing, the leaves and stems are where to look. Huckleberry leaves are always alternating along the stems, unlike many look-alike plants that have opposing leaf patterns. Huckleberry leaves are broad and lance-shaped, and their stems make a zig-zag pattern. They grow mostly on mountain slopes, at medium to high elevations."