Visit gaps allowed a week of bloom spread in 46 of 104 same-date US shrub groups in 2009-2014

We tested whether a public lilac and honeysuckle archive could support a study of bloom synchrony among plants at the same site. All 25,186 legacy first-bloom records had only one individual identifier per site, taxon, and year. Modern records gave 183 selected groups with multiple plants and prior absence reports for every plant. Of these, 104 had the same recorded bloom date for all plants. Visit intervals still allowed a true date range of at least seven days in 46 of those groups. We derived sharp integer-day range bounds and checked them by exhaustive enumeration and an independent calculation. The bounds assume correct status reports and one transition in each interval. They are not confidence intervals. Sparse repeated groups, selected planted shrubs, missing visits, and possible reporting errors limit use. We do not estimate a climate or pollution effect. The package includes source hashes, code, derived evidence, a raw rebuild check, and a figure.

phenology · observation bias · bloom synchrony · interval censoring · data support · lilac · honeysuckle