Vascular Plants of North Carolina
Account for Michaux's Saxifrage - Micranthes petiolaris   (Rafinesque) Small
Members of Saxifragaceae:
Members of Micranthes with account distribution info or public map:
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Section 6 » Family Saxifragaceae
Author(Rafinesque) Small
DistributionEssentially throughout the Mountains, and also ranging eastward into the higher elevations of the Piedmont, into the Sauratown, Brushy, and South mountains.

This is a Southern Appalachian endemic, being found from western VA and eastern WV, south to northwestern SC and northern GA.
AbundanceCommon over nearly all of the Mountains, but scarce in the southwestern tip. Uncommon to locally fairly common at higher elevations on Piedmont ranges.
HabitatThis Micranthes is another that is restricted to rocky places. It is quite widespread in habitats, from sunny to shady, and over many rock types. It prefers moist or damp rocky seepages, but it can also occur in dry rocky places, as well. Most sites are in rather exposed places and not in deep shade. It is, by far, the most widespread of the genus in the mountains.
See also Habitat Account for Montane Rock Barrens
PhenologyBlooms from June to August, and fruits shortly after flowering.
IdentificationThis Micranthes is the most familiar of the genus to most biologists in the mountains. It is easily identified just by its leaves, as are many in the genus. The cluster of basal leaves is typical for the genus; each leaf is wider toward the tip, but narrow; it is oblanceolate to spatulate, about 5-6 inches long and about 1.5 inches wide, with strong, saw-tooth serrations along the margins of the upper half of the blade. The lower half is mostly entire and tapers into the short petiole. The leaves are also quite hairy, more so than in most others in the genus. Also, some leaves may be reddish in color, especially by late summer. The flower stalk reaches about 1.5 feet tall and is very widely branched. The numerous white flowers are somewhat larger than in most other Micranthes species, being about 1/2-inch across. This is a species of rocky places in the mountains that does not need advanced knowledge to locate; it should be readily found in the more exposed rocky places.
Taxonomic CommentsNot only was this species with the others in the genus Saxifraga -- named as S. michauxii, but this one is somewhat different enough that it briefly went to another genus. It was named as Hydatica petiolaris, and it is still considered with this name by some references. Weakley (2018), NatureServe, and some others now use the name Micranthes petiolaris.

Other Common Name(s)Cliff Saxifrage, Mountain Saxifrage
State RankS4
Global RankG4G5
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US Status
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