2. Vinca minor L. (common periwinkle, myrtle)

Pl. 217 a–c; Map 902

Stems 10–150 m or more long. Leaves evergreen, strongly leathery, the petioles 1–2 mm long. Leaf blades 1.8–5.0 cm long, 0.8–2.5 cm wide, lanceolate, elliptic, or ovate, narrowed to a sharply or bluntly pointed tip, angled at the sometimes slightly asymmetrical base, the margins glabrous. Flower stalks 9–12 mm long. Calyx lobes 4–5 mm long. Corollas with the tube 8–12 mm long, the lobes 9–14 mm long. 2n=46. March–May.

Introduced, scattered, mostly south of the Missouri River (native of Europe, Asia; introduced widely but sporadically in the U.S. and Canada). Bottomland forests and mesic upland forests; also abandoned homesites, cemeteries, ditches, roadsides, and shaded, disturbed areas.

Vinca minor is the hardiest of the periwinkles and has long been cultivated in North America as an evergreen ground cover. The species is relatively aggressive, however, potentially covering large areas and climbing into trees. Although available very commonly in the horticultural trade, it is not recommended here for planting. Because it almost never produces fruits in North America, periwinkle usually escapes from cultivation by pieces of plants that are discarded by gardeners or that are washed into drainages from adjacent plantings. The species might be confused with a superficially similar invasive exotic, Euonymus hederacea Champ. ex Benth. (E. fortunei (Turcz.) Hand.-Mazz.) (wintercreeper, Celastraceae), but the leaves in that species have blunt teeth along the margins and the flowers have small, yellowish white, 4-parted corollas.