With access to many species within a genus growing in one place, botanic gardens are able to study different responses of related plant species to climate change. For example, within the genus Cornus, most species avoid seasonal freezing of woody tissue by supercooling (where water is cooled below 0°C without solidifying), but there is a temperature below which this is no longer possible. Some species, like the Red Osier Dogwood, have evolved to tolerate lower temperatures by recruiting special proteins in the cells to help prevent drying out when ice forms externally, which has allowed them to expand their range northwards. (Laboratory tests have shown that the Red Osier Dogwood can survive down to the unnaturally low temperature of –269°C, the temperature of liquid helium!) Studies like these will help us to model shifts in species range in response to climate change. Botanic Garden staff also routinely identify species that used to grow well but no longer do, or those recently able to survive beyond the confines of the glasshouse due to less frequent frosts.

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