Systematics of the Genus Morus L. (Moraceae)

Abstract

Morus L. (Moraceae Gaudich.) is a genus of trees distributed in temperate and sub-tropical regions worldwide. Species delimitation within the genus vary considerably among major taxonomic treatments, with different authors recognizing about five to 68 species. The main objective of this study is to evaluate the taxonomy of the genus Morus. We examined relevant taxonomic literature, studied herbarium specimens from across the world for morphology (particularly characters of the bud, leaf, inflorescence, style, and infructescence), and conducted field studies on native and naturalized Morus species in North America. We concluded that there are 13 species of genus Morus, including eight in Asia, one in Africa, and four in the New World. A brief discussion on the taxonomic history of the genus, a key to the species, specie description with information on type specimen(s), synonym(s), distributions and lists of examined specimens are provided along with a summary of phylogenetic relationships. Both empirical studies and simulation models indicate that the distribution of some Morus species may shift in response to climate change. This taxonomic revision is the most comprehensive genus-wide treatment since the revision by Koidzum, in 1917.

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