Video Highlight: Flower of the purple alder 2026
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Despite the cold weather, the purple alder is already in full flower in Vienna. Most of the catkins are open and ready to release pollen, as can be clearly seen here in the video (©Katharina Bastl (MedUni Vienna/Pollen Service Vienna)).
The purple alder usually begins to flower during Christmas week. Due to its hybridization between Japanese and Caucasian alder, the tree copes well with lower temperatures and can release pollen even at just above 0°C.