The leaves of Juniperus horizontalis are very small and sharp-pointed. Many of the leaves are in the range of 1.5 - 3 mm long, scale-like and tightly appressed to the stem. There are always some leaves of this type present. On some plants there may also be longer, spreading awl-shaped leaves to 10 mm long, though most are less than 7 mm in the material I have seen in Wisconsin. As in all Junipers the mature female cones are blue, often glaucus, berry-like structures.

The growth form is very distinctive in that the branches creep laterally along the ground, spreading horizontally, as the Latin name suggests, with only the short terminal branches sweeping upward. This is in strong contrast to the erect, tightly columnar shape of J. virginiana, whose leaves are very similar to those of J. horizontalis.

The range of Juniperus horizontalis lies mostly in Canada. It is represented in the U.S.A. primarily in widely scattered outliers from the main population. In Wisconsin this species is mostly restricted to the sandy shores of Lake Michigan and to a few very sandy areas near the Wisconsin and Mississippi Rivers.