Vascular Plants of North Carolina
Account for Thickleaf Meadow-rue - Thalictrum coriaceum   (Britton) Small
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Section 6 » Order Ranunculales » Family Ranunculaceae
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Author(Britton) Small
DistributionPresent throughout the mountains, including along the Blue Ridge Escarpment; apparently not found in upper Piedmont ranges.

This is a Central and Southern Appalachian endemic, ranging north to central PA, and south to extreme northern GA.
AbundanceUncommon to infrequent in middle and higher elevations, but rare at low elevations (below 2000 feet). It is not scarce enough for the NCNHP to place on the Watch List, perhaps as its habitats are not threatened, and as it has been recorded from all but two mountain counties. The editors feel that a State Rank of S3 is more appropriate.
HabitatThis species grows in rich, moist forests, in cool settings. It favors Rich Cove Forests, more so at middle elevations, as well as Northern Hardwood Forests, and various forests along seepages.
PhenologyBlooms from May to July, and fruits shortly after flowering.
IdentificationThis is one of the more robust and taller Thalictrum species, typically growing to 2.5-3 feet tall. The basal and cauline (stem) leaves are bi-ternately dissected (that is, doubly dissected, into about 9 leaflets per leaf), with each leaflet being 1.5-2 inches long and wide in the lower part of the stem, and smaller above. Leaflets are glove-like, with three lobes, the middle one the widest; however, each lobe has additional rounded teeth. Leaflets tend to be somewhat thick, at least thicker than in other tall meadow-rues. The uppermost leaves, just below the inflorescence, are sessile. The inflorescence, held above the leaves, is a broad but sparsely flowered panicle, with the flowers being male only and female only -- on separate plants. The male flowers have drooping filaments, which are extremely thin (filiform). It is most similar to the normally smaller T. dioicum, which blooms in early spring (March and April), and the stem leaf just below the lowest flowering branch has a petiole about 2 inches long. Other tall Thalictrum species have leaflets that normally have 3 rounded lobes (middle one widest and largest), but these lobes are not toothed; plus, the male flowers have filaments that are not filiform but wider. Though not a rare species in the mountains, it may take a bit of looking before you find this species, and even when you do find a tall Thalictrum, it is very important to be careful in its identification, as there is a rare one in the mountains (T. macrostylum).
Taxonomic CommentsNone

Other Common Name(s)Appalachian Meadow-rue, Leatherleaf Meadow-rue, Maid-of-the-mist. Several references use this last name, but it is highly idiosyncratic, imparting no taxonomic affinities, even to a plant group.
State RankS2S3 [S3]
Global RankG4
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