Tiarella stolonifera Nesom

Locations ofTiarella stolonifera Nesom in Virginia

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Detail

Family
Saxifragaceae
Botanical Name
Tiarella stolonifera Nesom
Common Name
Creeping Foamflower
Synonym(s)
Tiarella cordifolia L. var. cordifolia
Flora of Virginia Name/Status
Tiarella cordifolia L. (sensu lato)
Comments
Treatment follows Nesom’s recent revision of the genus in e. North America (Phytoneuron 31: 1-61, July 2021), which argues that taxa formerly recognized as varieties of Tiarella cordifolia merit species rank. Two species – Tiarella cordifolia and T. stolonifera – are attributed to Virginia. Although differing in several characters, these taxa are readily distinguished by habit in the field, with T. cordifolia forming discreet clumps and lacking the stoloniferous habit so typical of T. stolonifera. Additionally, the two are quite distinct geographically, with T. stolonifera nearly restricted to the mountains and T. cordifolia occurring primarily east of the mountains. Tiarella austrina (Lakela) Nesom, based on more elongate terminal lobe on leaf and only shallowly toothed compared with the typical variety, was mapped in far sw. Virginia in Amer. J. Bot, 1937, but a supporting specimen has not been seen and the record seems well out of range based on Nesom (2021). A modern molecular phylogenetic study would help clarify the relationships of all five taxa of eastern North American Tiarella .

In Virginia, Tiarella stolonifera is essentially restricted to the mountains, often at middle to higher elevations. It is readily distinguished from Tiarella cordifolia by its stoloniferous habit. The distribution map is based on the map in Nesom (2021), modified slightly by Virginia herbarium data. If this taxon is accorded full species status, as Nesom argues for, then the name Tiarella cordifolia would apply to the former T. cordifolia var. collina and this taxon would have to be renamed.
Habitat
Tiarella stolonifera occurs in cove forests, deep-soiled ridge forests, montane alluvial forests, and crevices of shaded rock outcrops. It favors, but is not restricted to, more base-rich soils. It is frequent in the sw. mountains, infrequent in the c. and n. mountains, and rare in the sw. Piedmont.
Native Status
Native

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