| Peak concentration, pollen grains/m3 |  | |
---|---|---|---|
year (season) | J. ashei, from southern Oklahoma, Texas | J. virginiana from local Tulsa area | foreign (J. ashei) vs. vs. local (J. virginiana) pollen |
1987–88 | 175 | 655 | 0.27:1 |
1988–89 | 546 | 1057 | 0.51:1 |
1989–90 | 257 | 1115 | 0.23:1 |
1990–91 | 333 | 4442 | 0.07:1 |
1991–92 | 158 | 1156 | 0.14:1 |
1992–93 | 802 | 1248 | 0.64:1 |
1993–94 | 2027 | 1311 | 1.55:1* |
1994–95 | 947 | 1485 | 0.64:1 |
1995–96 | 2411 | 2027 | 1.19:1* |