Same-date first and full bloom reports were rare in four US shrub samples in 1965-2008

We tested whether warmer springs were linked to more first-bloom and full-bloom reports on the same date. Four US region and period samples had only 16 such reports among 15,153 selected pairs in 1965-2008. Plant and year models gave slopes from -0.136 to -0.010 percentage points per C. All four adjusted intervals included zero. The later western slope depended on one event plant. A two-day threshold gave one negative early western interval, but the result did not repeat in the later West. Same-date reporting is too rare here for a strong replicated weather test. It does not identify visit error or rapid flower development. Missing visits, complete-pair selection, mixed taxa, coarse monthly weather and rare events limit inference. We do not test pollution, weather extremes, or causal climate change. The package has a raw-source rebuild, exact source hashes, the panel, code, all results, event records and a figure.

phenology · observation bias · same-date reports · lilac · honeysuckle · temperature · rare events · null result