Flora of North America species comparison

Tiarella macrophylla was described from Tyron Mountain, North Carolina; the specimen consists of basal leaves of Heuchera villosa and racemes of T. cordifolia. Tiarella wherryi and T. cordifolia have been differentiated primarily on the basis of lack of stolons in T. wherryi. Such plants grow in mixed populations and it has been impossible to differentiate taxa on the basis of herbarium specimens. It is also thought that the differences between the taxa might be a result of altitudinal variation in habitat. Attempts by Lakela to distinguish var. cordifolia and var. austrina on the basis of leaf dimensions and marginal dentation have been thwarted by continuous variation in these characteristics.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 3 (3 in the flora).

Varieties of Tiarella trifoliata have overlapping ranges and differ from each other in leaf form and marginal dissection. Their floral features are stable throughout. They were previously suspected of hybridizing when sympatric. They are differentiated along elevational gradients and often remain distinct in sympatric populations.

(Discussion copyrighted by Flora of North America; reprinted with permission.)