It is often observed from the Rim above Crater Lake, and from boats on the lake, that great masses of sulphur are floating on the water. This arouses the curiosity of the tourists and explanations are continuously in order. The entire region being of volcanic origin, the conclusion is generally offered that the sulphur is due to this fact. Examination, however, discloses that this wheat substance is pollen, probably of the lodgepole (P. contorta) blown in clouds from a distance and dropped upon the water in significant quantities to be visible from the cliffs above the lake.