Airborne pollen survey for Lincoln, Nebraska: I. Trees.

Pollen counts in 1988, 1989, and 1990 revealed 14 different tree pollen types. The main tree pollination season in Lincoln extends from late February or early March through the end of May. First linden and then pine and juniper extend the trees through October. The sequence of flowering for the plants is similar to that found in other regions of the country. The highest counts (peaks of ca. 1000 grains/m3) are in March, April, and May when the largest number of trees are in bloom. Counts fall through June (highest ca. 300 grains/m3) and July (highest at ca. 35 grains/m3) when grasses and some weeds are flowering.