Morus

Trees or shrubs, deciduous; sap milky. Terminal buds surrounded by bud scales. Leaves alternate; stipules caducous. Leaf blade ovate to broadly ovate, margins entire or lobed, dentate; venation nearly palmate. Inflorescences pedunculate catkins, erect or pendent, cylindric. Flowers: staminate and pistillate on same or different plants. Staminate flowers: sepals 4 (4-5 in M. alba); stamens 4, inflexed. Pistillate flowers: sepals 4, green, of 2 sizes, ciliate; ovary superior, 2-locular; style 2-branched, branches linear. Syncarps short-cylindric; each achene enclosed by its enlarged, fleshy calyx. x = 14.

Distribution

Widespread in temperate and tropical regions, North America, Europe, and Asia.

Discussion

Species 10 (3 in the flora).

Morus nigra Linnaeus has been reported in floras by various authors (J. K. Small 1903, 1933; R. W. Long and O. Lakela 1971), apparently based on dark-fruited M. alba. It is native to Asia, commonly cultivated in Europe for its fruit, and locally naturalized in southern Europe. Occasionally cultivated in North America, it is not known to be naturalized. Because of the similarity to and confusion with M. alba, some American authors place it in synonymy with that species.

Selected References

None.

Lower Taxa

Morus alba, Morus microphylla, Morus rubra

Key

1	Mature leaf blade less than 7 cm, abaxially harshly scabrous or pubescent, adaxially harshly scabrous; petiole to 1.5 cm.	Morus microphylla
1	Mature leaf blade usually more than 8 cm, adaxially slightly if at all scabrous; petiole 2 cm or more.	> 2
2	Leaf blade abaxially glabrous or with pubescence only along major veins or in tufts in axils of principal lateral veins and midribs, adaxially glabrous to sparsely pubescent.	Morus alba
2	Leaf blade abaxially pubescent or puberulent, adaxially with short, stiff, antrorsely appressed trichomes, usually scabrous.	Morus rubra