In a recent treatment of the family Myricaceae most of the species previously in the genus Myrica have been placed in the genus Morella. This latter genus now has about 50 species, ranging from North America, Europe, Africa, and Asia. Only a few plants remain in the genus Myrica, including Myrica gale, bog-myrtle, and Myrica hartwegii, the California native, Sierra myrtle.
Key to differentiate Myrica and Morella (Herbert, J., Novon 15:293-295. 2005)
Myrica Shrubs deciduous; leaves with sunken stomata; inflorescences born on previous year’s growth; fruits dry with adherent spongiosa [soft and spongy] bracteoles [a small bract], water dispersed. Now only about four species in this genus, Myrica gale (sweetgale) and three others (M. hartwegii, M. holdridgeana, and M. inodora).
Morella Shrubs or trees, evergreen (also semi-evergreen?); leaves with stomata not sunken; inflorescences born of the present year’s growth; fruits papillose [having minute papillae {short, rounded bumps or projections}], fleshy, sometimes with a waxy covering, bird-dispersed. Many species formerly in Myrica are now in Morella; about 50 species in this genus.