Etymology -The name refers to the fruits which resemble those of
the Bilberry (Vaccinium myrtillus). There are four species of
Myrtillocactus which are recognized and unlike most other cactus
genera, the taxonomy of Myrtillocactus is quite settled and
universally accepted. The four species are all similar in that
they are tree-like, much-branching plants with few (4-8)
prominent ribs. Typically the ribs features a single, thick,
long central spine and only a few thick, short radial spines or
the areoles may be spineless. Flowers are quite small at less
than an inch (2.5cm) and have short floral tubes which keep the
flowers fairly tight to the stems. An unusual feature of
Myrtillocactus is that the areoles may produce multiple flowers.
The flowers are a greenish-white color, waxy and somewhat
translucent. Large sections of the ribs will feature flowers all
at once and later give rise to blue-berry-like fruits which are
very tasty and have been used by native people of Mexico for
centuries and are still harvest