| Author | Epling | |
| Distribution | Limited to the eastern Piedmont, south to Moore County, but mainly in the diabase sill areas in Granville and Durham counties.
This species has a wide range, from MA to ND, and south to western FL, AR, and OK. It is quite scarce east of the mountains, and south of VA it is mainly limited to the lower Piedmont.
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| Abundance | Declining in the state, for uncertain reasons; a number of recent populations have not been relocated, owing to competing vegetation, embankment disturbances, and other factors. Rare to almost very rare in the northeastern Piedmont, essentially just in Granville and Durham counties. Casual to very rare in other counties in the eastern Piedmont -- Orange, Johnston, and Moore. As a result, the website editors suggest the State Rank be upgraded from S2 to S1S2. The species is rightfully listed as State Endangered. | |
| Habitat | This species requires high pH soil in NC, and is found in dry places with very little competition. It grows on roadbanks, diabase barrens and glades, and openings in dry woods. |
| Phenology | Blooms from April into June, and fruits shortly after flowering. | |
| Identification | This species is easily confused in the field (and in the literature) with the other two dwarf species in the genus -- S. australis and S. parvula. It grows to about 6 inches tall, usually unbranched, but is quite slender. It has numerous pairs (opposite) of stem leaves, being lanceolate to triangular, sessile, ascending, about 2/5-inch long and half as wide, with entire or nearly entire margins. The other two species have wider and more ovate leaves and are more pubescent overall. From the upper leaf axils grow the quite small blue flowers, each one about 1/3inch long. These species are very difficult to spot, even in flower; it is often the capsule that more readily catches the attention than does the flower. To best find S. leonardii, look very closely on roadbanks where there is circumneutral soil, as this species is easily shaded out by competing vegetation on flat ground. | |
| Taxonomic Comments | The three small species in the genus have been greatly confused in the past, some references like RAB (1968) even lumping all three into one, called S. parvula in that reference. Oddly, NatureServe calls the species as S. parvula var. missouriensis.
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| Other Common Name(s) | Shale-barren Skullcap, Glade Skullcap | |
| State Rank | S2 [S1S2] | |
| Global Rank | G4T4 [G4] | |
| State Status | E | |
| US Status | | |
| USACE-agcp | | |
| USACE-emp | | |
