White stonecrop. Berlin, Germany. © Matt Lemon Photography. All Rights Reserved.
The white stonecrop (sedum album) is found in the northern temperate regions of the world, often growing in crevices or free-draining rocky soil. As a long-day plant it grows vegetatively for most of the year and flowers in June and July. The white stonecrop is able to acclimate to its environment. It can switch between C3 carbon fixation and crassulacean acid metabolism (CAM) depending on the availability of water. CAM saves water as the stomata on its leaves only open to allow CO2 to diffuse into the leaves at night when the temperature (and therefore evapotranspiration) is lower. Drought stressed plants are also more susceptible to photoinhibition which CAM may help to protect against.
As the long dark winter in Germany only ended recently, photoinhibition, which is caused by an overexposure to light, is hardly a problem for plants or people here these days. Instead, the latter welcome every ray of sunlight with a serene smile, while the former fill the city with colours. This photo was taken as the sun reached the pots and plants on the terrace outside my kitchen, which currently doubles as my study in the mornings.