Beetle Pollination of Magnolia praecocissima var. borealis

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Abstract
The floral biology and pollination of Magnolia praecocissima var. borealis, a tall tree blooming before leaf‐emergence in early spring, were studied in Hokkaido, northern Japan. The flower is protogynous, and each flower lasts about 9 days without closing its petals. The mean duration of the female‐stage and the male‐stage flowers is about 4 and 4–5 days, respectively. The flowering period of an individual tree can be divided into three sexual phases: female, bisexual, and male. Manual pollination and bagging experiments showed that the plants were self‐compatible and that pollinators were necessary for a flower to produce seeds. It was observed that several species of small pollen‐foraging beetles were the most effective pollinators. The male‐stage flowers offered pollen as a reward, while the female‐stage flowers offered no reward; it is likely that the non‐rewarding female‐stage flowers mimic the rewarding male‐stage flowers. The pollination syndrome of Magnolia praecocissima var. borealis differs from North American Magnolia species in its long‐lasting flowers, is no closure of flowers at night, and in lack of food in the female phase.