Pollination of the eastern dwarf mistletoe.

Flowering and pollination of Arceuthobium pusillum growing on Picea mariana were studied in Carlton County, MN. Staminate flowers opened in April and abscission was complete by mid-June. Average number of pistillate flowers per aerial shoot ranged from 4.8-5.1. From the flowering period of seed dispersal (September), 36-59% of pistillate aerial shoots were lost. Based on March flower counts, 0.3-2.4 fruits matured per aerial shoot, ie 5-35% of pistillate flowers developed into mature fruits. Although insect exclusion studies demonstrated that wind pollination did occur, few grains of Arceuthobium pollen were collected with vaseline slides or a Rotorod sampler. Fifty-nine species of insects trapped on sticky-board traps carried pollen of Arceuthobium. Entomophily is the most important pollination mechanism for this dwarf mistletoe. -Authors