Plant of the Week
White mountain-saxifrage (Saxifraga paniculata Mill.)
By Christopher Mattrick
White mountain-saxifrage is a small, but exceedingly handsome member of the saxifrage family. It is found worldwide in northern boreal regions. In North America, it reaches its southern limit in the northern portion of New England, but European populations range as far south as Greece. In North America, it is reported from all the northern New England states, New York, Michigan, and Minnesota, as well as all Canadian Provinces east of Manitoba and the Northwest Territories. It is globally common with a global rank of G5; however in the United States it is considered endangered or threatened in all states where it occurs except Vermont where it is uncommon. The white mountain-saxifrage occurs on the White Mountain, Green Mountain, and Superior National Forests.
In the southern part of its North American range, it most typically occupies small-vegetated ledges and cracks in nearly vertical cliffs. Areas surrounding populations are typically free of other vegetation, and therefore competition. Reports from known locations repeatedly reference bedrock types as calcareous, basalt, basic or anorthosite bedrock at indicating that the species is likely a calciphile. White mountain-saxifrage is a perennial species growing in small, tight rosettes of basal leaves. The leaves are fleshy and secrete liquid from special structures at the tips of the basal leaves. As the liquid evaporates it leaves behind a sort of salt rime on the tips and edges of the finely toothed basal leaves adding to the striking beauty of this species. In July, each rosette sends up a single flowering stalk containing multiple five-petalled white flowers. The flowers stand out in sharp contrast to the gray background of cliff faces. The flowers and leaves are so distinct that either can be used for accurate identification.
The species has undergone many taxonomic changes since it was first described in 1768. It has been known variously as Saxifraga paniculata and Saxifraga aizoon. The original descriptions of both species appear to be based on European specimens. When the species was first discovered and examined in North America is initially considered its own variety and then sub- species of Saxifraga aizoon ssp. neogaea. The North American species are now subsumed under Saxifraga paniculata, but some debate concerning a North American variety continues. The common name white mountain-saxifrage does not refer to the White Mountains of New Hampshire. The first observation of this species in the White Mountains of NH appears to have been in 1939 and as recently as 1964 perhaps the most knowledgeable White Mountain botanist of the day indicated, “the white-mountain-saxifrage does not occur in the White Mountains”. Instead, the name is applied to distinguish it from yellow mountain-saxifrage. Note the placement of the hyphen in the names; the white and yellow are a reference to the flower color.
One final fascinating fact about this species is that people native to the arctic tundra region where this species also grows, once made a sauerkraut-like food of the leaves by stuffing them in a seal skin bag and allowing it to ferment. Although intriguing its aesthetic value probably outweighs its value as a food source today.