カワラハンノキの開花：Kawarahannoki (Alnus serrulatoides)

桂川沿いのカワラハンノキが開花しています。昨年よりは2週間ほど遅い開花です。雄花は大きく下方に垂れ、雌花は小さく上向きに。雄花の花粉は開花と共に風に乗って拡散します。雌花序を拡大すると、鱗片状の苞の間から柱頭が各苞に2個出ています。

The Japanese alder trees along the Katsura River are in full bloom. The flowering is about two weeks later than last year. The male flowers are large and hang downward, while the female flowers are small and point upward. The pollen from the male flowers is dispersed by the wind as they bloom. If you zoom in on the female inflorescence, you can see two columnar heads on each bract coming out from between the scaly bracts.

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Photos 2022-02-16