Table 1.
Mean pollen densities on milkweed leaves inside a cornfield for different studies
| Study | Anthesis level | Mean pollen density (cm2) | No. of leaf subsamples | No. of rain events* |
|---|---|---|---|---|
| Maryland 1999 | Near peak | 65.7 | 66 | 0 |
| Iowa 2000b | 100% | 425.6 | 136 | 1 |
| Iowa 2000c | 75% | 203.8 | 180 | 2 |
| 100% | 157.1 | 180 | 2 | |
| Post anthesis (10 days) | 101.2 | 135 | 1 | |
| Iowa 2000d† | 5% | 58.0 | 36 | |
| 30% | 109.5 | 36 | 1 | |
| 50% | 122.7 | 36 | 2 | |
| 75% | 115.7 | 32 | 2 | |
| 100% | 231.4 | 38 | 0 | |
| Ontario 2000 | Day 6 | 69.7 | 350 | 1–3 |
| Day 11 | 97.7 | 305 | 0–2 | |
| Maryland 2000‡ | Day 3 | 9.7 | 48 | 2 |
| Day 6 | 67.3 | 46 | 2 | |
| Day 9 | 161.3 | 46 | 3 | |
| Day 14 | 61.8 | 86 | 2 |
*
Number of rain events since previous sample, since the start of anthesis, or in the previous 7 days; for Ontario the intersampling intervals for each of the six fields covered different time periods.
†
Only data from 25 m within the field were used.
‡
Data from 1, 3, 5, and 10 m within the field were used; only upper leaves included.