Allergies to cedar pollen are so significant that they have been dubbed "Cedar Fever". The cedar allergy season is actually caused by a couple of different, but related plants. The plants are so closely related that the pollen is almost identical under a microscope. Whether you call it Ashe Juniper or Mountain Cedar, (Juniperus Asheii ) is the real offender. These trees seem to be everywhere in the Hill Country and they produce enormous amounts of pollen. So much so, that the male trees appear to be smoking as they release the pollen from tiny cones. The female trees produce clusters of blue/green berries. Small amounts of the pollen appear in our air samples in November but the peak of the season is typically late December through late January.