See Sabina scopulorum and Sabina deppeana  and  Sabina osteosperma.

Semi-desert. Shrublands, woodlands. Spring.
Painted Desert area of Petrified Forest National Park, Arizona. March 24, 2007.

S. monosperma is typically a small, symmetrical tree about three meters high with a number of thin, curved branches emanating from the base.  The taller S. osteosperma often has a more open appearance with few stout branches from a massive central trunk.  S. monosperma grows in eastern Colorado, New Mexico, and Arizona but is not found in western Colorado.

George Engelmann named this tree Juniperus occidentalis variety monosperma in 1878 from specimens collected (by Engelmann?) probably near Pike's Peak.  Charles Sargent named it Juniperus monosperma in 1896 and Per Axel Rydberg named it Sabina monosperma in 1905.

Semi-desert. Shrublands, woodlands. Spring.
Petrified Forest National Park, Arizona. March 24, 2007.

S. monosperma is dioecious (male and female flowers on separate trees) whereas S. osteosperma is usually monoecious.  In the photograph at left, male flowers are about to open and flood the air with yellow pollen.

Semi-desert. Shrublands, woodlands. Spring.
De-Na-in/Bisti Wilderness, October 8, 2007.

Female trees have blue, cone-like structures which mature in one season.  The cones house the seeds and are full of liquid resin --  in contrast to the dry and mealy cones of S. osteosperma.