The three species noted here are the most commonly cultivated Ligustrum species in Michigan and the northern States, especially for hedges, and they doubtless escape far more often than the maps suggest. Two other species may occasionally be grown in southern Michigan, but have not been seen as escapes, although both are known to escape in the southeastern United States. Ligustrum quihoui is a relatively showy species blooming very late (July-August) with leaves distinctly widest above the middle (narrowly obovate). Ligustrum sinense may be hardy in southernmost Michigan; it has inflorescences distributed both terminally and laterally, unlike the three species treated below, which have strictly terminal inflorescences. Both these species are semi-evergreen, with leaves persisting late into the fall or early winter. See Maddox, Byrd, Jr., & Serviss (2010) for more details.
Numerous Ligustrum cultivars have been named, as have hybrids of L. vulgare × L. ovalifolium (L. ×vicaryi Rehder) and L. obtusifolium and L. ovalifolium (Ligustrum ×ibolium Coe).
1. Corolla tube equaling or shorter than the lobes; leaves glabrous; twigs and pedicels glabrate to finely puberulent (hairs all or mostly less than 0.2 mm long).
1. Corolla tube about twice as long as lobes, or longer; leaves glabrous or pubescent; twigs and pedicels glabrous or pubescent with many hairs over 0.2 mm long.
2. Twigs, pedicels, calyx, and midrib of leaves beneath pubescent with many of the hairs over 0.2 mm long; leaves promptly deciduous.
2. Twigs, pedicels, calyx, and leaves glabrous or nearly so; leaves persistent well into winter.
All species found in Ligustrum
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 4, 2020. https://michiganflora.net/genus.aspx?id=Ligustrum.