Climate change increases flowering duration, driving phenological reassembly and elevated co-flowering richness.

Changes to flowering phenology are a key response of plants to climate change. However, we know little about how these changes alter temporal patterns of reproductive overlap (i.e. phenological reassembly). We combined long-term field (1937-2012) and herbarium records (1850-2017) of 68 species in a flowering plant community in central North America and used a novel application of Bayesian quantile regression to estimate changes to flowering season length, altered richness and composition of co-flowering assemblages, and whether phenological shifts exhibit seasonal trends. Across the past century, phenological shifts increased species' flowering durations by 11.5 d on average, which resulted in 94% of species experiencing greater flowering overlap at the community level. Increases to co-flowering were particularly pronounced in autumn, driven by a greater tendency of late season species to shift the ending of flowering later and to increase flowering duration. Our results demonstrate that species-level phenological shifts can result in considerable phenological reassembly and highlight changes to flowering duration as a prominent, yet underappreciated, effect of climate change. The emergence of an autumn co-flowering mode emphasizes that these effects may be season-dependent.

Taxonomic changes in Oenothera sections Gaura and Calylophus (Onagraceae).

The long-recognized genus Gaura was shown recently to be deeply nested within one of two major clades of Oenothera. New molecular data indicate further taxonomic changes are necessary in Oenothera sect. Gaura. We make these changes here, including three new combinations, in advance of the Onagraceae treatment for the Flora of North America. The new phylogenetic studies show that several pairs of taxa treated as subspecies in the most recent revision by Raven and Gregory (1972) had independent origins within sect. Gaura, and are here elevated to species level (Oenothera nealleyi for Gaura suffulta subsp. nealleyi; Oenothera dodgeniana for Gaura neomexicana subsp. neomexicana; and Oenothera podocarpa for Gaura hexandra subsp. gracilis). Also, a nomenclatural problem in Oenothera sect. Calylophus is corrected by adopting the name Oenothera capillifolia Scheele for the species known previously, and nomenclaturally correct, as Calylophus berlandieri Spach. This problem necessitates a new combination Oenothera capillifolia subsp. berlandieri.