Early Bloom of Hamamelis vernalis Documented Across Missouri
iNaturalist Community
Phenology
If winter-blooming shrubs like witch-hazel are flowering weeks ahead of schedule, the insects that pollinate them — and the birds and plants that depend on those insects — may all be falling out of sync, potentially affecting the ecosystems in the parks and gardens near you.
Witch-hazel is one of the few plants that blooms in the dead of winter, making it a key early food source for pollinators. Across Missouri, people using the nature app iNaturalist noticed it flowering a full three weeks sooner than normal this year. Scientists linked this early bloom to an unusually warm January, suggesting that as winters get milder, the timing of nature's calendar is shifting in ways we can actually see.
Key Findings
Ozark witch-hazel bloomed approximately 3 weeks earlier than the historical average across 47 community observation sites in Missouri.
January mean temperatures were +2.8°C above the 30-year climate norm, strongly correlating with the early bloom timing.
The phenological shift was documented through citizen science observations on iNaturalist, demonstrating the value of community-collected data for tracking climate-driven change.
chevron_right Technical Summary
Ozark witch-hazel is blooming three weeks earlier than usual across Missouri, with community scientists documenting the shift at 47 sites. The change tracks closely with January temperatures running nearly 3°C warmer than the 30-year average.
Abstract Preview
Community observations document Ozark witch-hazel blooming 3 weeks earlier than historical average across 47 observation sites in Missouri. Phenological shift correlates with above-average January ...
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Witch-hazels or witch hazels (Hamamelis) are a genus of flowering plants in the family Hamamelidaceae, with three species in North America, and one each in Japan (H. japonica) and China (H. mollis). The North American species are occasionally called winterbloom.