Morus

Content

Description

Trees, dioecious, unarmed, shoot apices shed, with axillary scaled resting buds. Leaves distichous; stipules free, almost lateral. Inflorescences unisexual, usually solitary on the lower leafless nodes of new (short-)shoots arising from well-developed scaly resting buds on wood of the previous season, ebracteate or bracteate. stamens 4, inflexed in the bud. ovary free, style subterminal, stigmas 2. fruit with a broad base, exocarp thin-fleshy, thicker on the seed-bearing side, indehiscent, endocarp crustaceous with a woody plug towards the hilum; seed with endosperm, embryo curved, cotyledons equal and flat, not enclosing the long radicle.

Distribution

Africa present, Asia-Tropical, East Asia present, North America present, Northern America, SE Asia present, SE United States present, neotropics present

The genus comprises ten to ﬁfteen species, most of them in temperate to subtropical regions of the northern hemisphere, some in montane habitats in the tropics (M. insignis Bureau in the Neotropics and M. macroura in SE Asia and Malesia), one in the tropical lowlands of Africa (M. mezozygia A. Chev., as evergreen tree in rain-forest or as deciduous tree in drier conditions), and one in dry regions of SE United States and Mexico (M. celtidifolia Kunth). The North American M. rubra L. is closely related to the group of species associated with northern temperate to subtropical conditions and centred in the Himalayan and East Asian region and constituting a complex of very closely related taxa for which a recent taxonomic evaluation is still wanting; this complex comprises, e.g., M. alba L. and M. nigra L.

Morphology

The association with northern temperate conditions is morphologically expressed in the abscission of shoot apices, the presence of ± well-developed scaled resting buds, and deciduousness, features which are at least partly still pertained by the tropical lowland species.

Taxonomy

Leroy () recognised three subgenera: Afromorus (with M. mesozygia), Gomphomorous (with M. insignis), and Eumorus with the rest of the species.

Cytology

Polyploids (4x, 6x, 8x, or even 22x) are found in the Himalayan-East Asian complex of taxa.

Uses

The genus has a very long historical association with mankind for edible fruits of many species and for the cultivation of the slik-moth.

Citation

Endl. 1837: Gen. Pl. p 278

Nakai 1927 – In: J. Arnold Arbor. 8. p 234

C.C. Berg 2001 – In: Fl. Neotrop. Monogr. p 25

Bureau 1873 – In: DC., Prodr. 17. p 237

Gagnep. 1928 – In: Fl. Indo-Chine. p 706

Baill. 1875 – In: Hist. Pl. p 190

Engl. 1888 – In: Engl. & Prantl, Nat. Pflanzenfam. 3. p 72

Benth. & Hook.f. 1880 – In: Gen. Pl. p 364

L. 1848 – In: Gen. Pl. p 33