Juniperus virginiana

Eastern red cedar (Juniperus virginiana) is a medium-sized tree that is found throughout the eastern half of the United States; however, the species is encroaching across the prairie states. The results of this invasion is the conversion of grasslands into eastern red cedar savannas or woodlands. Easten red cedar has separate male and female trees. Male trees produce pollen cones, and female trees produce small seed cones that look like small berries.

Eastern red cedar is the only Juniperus species native to eastern Oklahoma. Pollen release begins in early February and continues through April. Peak concentrations generally occur in late February or early March. The pollen is allergenic and is the cause of late-winter or early spring hay fever symptoms. Long term air sampling in Tulsa has shown that the pollen levels have been increasing over time, which parallels the increasing population of eastern red cedar trees in Oklahoma.