A photograph and written entry by Tamara Bonnemaison today. She scribes:
During a morning with frost a few weeks ago, the silvery-tipped leaves of this Saxifraga paniculata stood out among the many other beautiful specimens in UBC Botanical Garden’s Alpine Garden. Daniel has been patiently teaching me to use the BPotD camera, and despite my best efforts, I was not quite able to capture the glow of the morning sun playing across the surface of the saxifrage’s rosettes. This photo comes fairly close; for the rest, you’ll need to use your imagination.
Saxifraga paniculata, also known as lime-encrusted saxifrage and white-alpine saxifrage, is a circumboreal species that is found in calcareous boreal, subalpine, and alpine habitats in North America, Europe, Scandinavia, Iceland, and Greenland. This species’ common name is a result of lime-secreting pores on the leaf edges, which give the toothed leaves a silvery or ‘encrusted’ appearance. What I had at first thought to be the work of a particularly hard frost was actually the combination of frost and secreted lime, both of which contributed to making this plant literally glow against the shaded ground.
Encrusted saxifrage is a stoloniferous perennial that is extremely hardy. Its stiff, leathery leaves form 3cm tall rosettes that close as they become desiccated, with the outer leaves acting as an evaporative and solar shield for the younger leaves in the centre of the rosette. During times of extreme drought, these outer leaves dry out completely, but the plant itself is protected and survives. The species is also able to survive a short growing season and long periods of cold-induced photoinhibition (meaning that it is so cold that very little photosynthetic activity can occur). On top of having to survive extreme cold, drought, and insolation, Saxifraga paniculata must contend with an irregular supply of pollinators. However, it can both reproduce vegetatively through its stolons and self-pollinate.
The perfect flowers of lime-encrusted saxifrage are quite beautiful. I came across this species at the wrong time of year to capture the white, five petaled flowers, but thankfully these have been amply photographed by others. The Acta Plantorum website has many photos that show the curious purple-dotted white petals, as well as some images of lime-encrusted saxifrage growing in its alpine habitat.