Colette S. Berg, Naomi Burr, Jennifer J. Weber
Rhodora 125 (1001), 1-18, (28 June 2024) https://doi.org/10.3119/22-18
KEYWORDS: climate change, flowering time, herbarium records, native plants
Flowering phenology, or the timing of plant reproduction, is a key component of plant fitness, influencing plant survival, reproduction, and the presence (or absence) of temporal reproductive barriers between closely related species. Flowering phenology often varies across space, and advancing spring phenology is a common response to anthropogenic climate change. Characterizing phenological variation at higher taxonomic levels can reveal whether related species vary in their sensitivity to climate change. We characterized flowering phenology across space and through time in the dimorphic cleistogamous genus Triodanis using vetted digital herbarium and iNaturalist records of Triodanis species spanning 153 years across the contiguous United States. We found considerable overlap in peak flowering time in all seven Triodanis species, suggesting that factors other than flowering time, such as self-fertilization, may contribute to the maintenance of species barriers in this genus. Geography influenced the peak-flowering date in four species, but the direction and strength of these relationships varied between species, perhaps reflecting local variation in abiotic conditions and species-level differences in flowering cues. We found phenological advancement over the past century in four of seven Triodanis species, suggesting that this genus is potentially tracking climate change through flowering time shifts.