This taxon is centered in east-central states. It is close to australis, which has an overlapping southeastern range; it may generally occur in drier habitats (W). S. parvula reportedly differs from australis as follows, based on varied sources (F, Y; Sorrie et al. in W): leaf veins usually unbranched along margins (versus tending to anastamose), lower surfaces "dotted with sessile glands" (Y, versus not so) but clothed with largely eglandular hairs (versus only stipitate-glandular hairs or nearly so); upper stems retrorse or spreading eglandular or stipitate-glandular (versus antrorse eglandular and spreading stipitate-glandular); fresh plants with strong turpentine odor (versus inodorous). However, these differences are not always clear. A few colls. from BULL and WAYN (MDKY) may be somewhat intermediate. Both taxa usually occur on deeper or richer soils than leonardii. All three taxa (= parvula sensu lato) are distinct from congeners in their "stolons producing thick moniliform tubers" (F); these are similar to tubers of the Stachys cordata group.. Also, flowers are relatively small on average, with corollas 6-11 mm long (versus 8-10 mm or more). And leaves are relatively small: 0.5-2 cm long (versus 1.5-4 cm or more).