Late-blooming Rose (Rosa acicularis) in Fairbanks

Observation by Dana Brown:

Rosa acicularis flowering very late in season (October)

Comments from LEO Editors:

This observation has been shared with Katie Spellman, ecologist at the International Arctic Research Center in Fairbanks, who is collecting observations of late blooming plants to better understand a possible interaction between warming temperatures and plant response.

Since 2017, LEO has received 19 posts about late blooming plants across Alaska. In post documenting a rose blooming in September, Pamela Diggle, a professor in the Ecology and Evolutionary Biology Department at the University of Connecticut, wrote:

"Plants rely on a variety of signals so that they go dormant at the right time. Going dormant at the right time is critical for flowers or leaves. If they delay too long, they risk being killed by low temperatures...Temperature is probably very important and temperatures probably do cause the plant to make some chemical signals, but those signals are not necessarily released by the plant into the environment. Rather, they remain inside the plant and cause the flowers to open prematurely.

Temperatures across the state are trending warmer. The average annual temperature in Fairbanks has increased 3.7 degrees between 1949-2016. During 2020, temperatures in Fairbanks have been warmer than normal in late September and early October. Erica Lujan