https://www.cabi.org/isc/datasheet/34816
A small to medium tree growing up to 15 m, M. alba has a short trunk, and a rounded crown with a dense canopy of spreading branches. Leaves are alternate, simple, 6-18 cm long, 5-13 cm wide, broadly ovate, dentate or lobed with 3 prominent veins running from the rounded or obliquely cordate base. Somewhat polymorphic, leaves are shiny green on the adaxial surface, paler and slightly hairy underneath. Bark is light brown to grey, smooth but may be furrowed. Dioecious, male inflorescences are small with 4 stamens, filaments inflexed in bud, green and borne on long catkins. Female flowers are inconspicuous, perianth with 4 free or almost free segments, aggregated in short spikes. Fruit is an ovoid or cylindrical syncarp composed of achenes, pendunculate, red when immature, blackish-purple, purple or greenish-white when mature, 1-2.5 cm long (Global Invasive Species Database, 2016; Tutin, 1964).
Two botanical varieties of M. alba are recognized (Zhou and Gilbert 2003): varieties ‘alba’ and ‘multicaulis’. The leaf blade of ‘alba’ is 5-15 cm, fruits are ovoid to ellipsoid, blackish purple when mature. The leaf blade of var. ‘multicaulis’ is <30 cm with cylindric fruits which are greenish-white to purple when mature.