Latin name: Morus alba
Source material: Pollen
Common names: White mulberry, Silkworm mulberry
The Mulberries, comprising about 10 species, are monoecious or dioecious trees or shrubs. The origins of the Mulberry tree (M. alba) are mainly in China, Japan, Thailand and Malaysia. The tree is now found throughout the world. Only 2 species are native to North America, but several others have been introduced.
The Mulberry is a deciduous tree growing 18 to 20 m in height, with a wide-spreading, round top. The trunk is light grey. The green leaves may be unlobed, mitten-shaped, or 3-lobed.
The trees bear the staminate and pistillate flowers on different branches of the same tree or on different trees; these flowers are minute, and the staminate ones are in cylindric spikes up to 2 cm long (1). The tree flowers in spring and is wind-pollinated, and the pollen is dominant in its region. The pollen is highly allergenic. The seeds (fruits) ripen from summer. The fruit is an aggregate, 1 to 5 cm long, white becoming pink and then purplish to nearly black.
These trees are extensively grown in locations such as China, Southern Europe and India for their leaves as food for silkworms. Mulberries are popular for street planting and as garden and roadside ornamentals in the eastern US, Europe, and other places. Having escaped, trees often appear growing wild on roadsides and along fencerows.
The fruits may be eaten raw or cooked. The wood is valued for sporting goods due to its elasticity and flexibility when steamed.
No allergens from this plant have yet been characterised.
An extensive cross-reactivity among the different individual species of the genus, as well as a certain degree of cross-reactivity within the family Moraceae (including Breadfruit, Ficus spp. [Weeping fig], Fig, India rubber plant, and Jackfruit) could be expected (2).
Mulberry pollens can induce asthma, allergic rhinitis and allergic conjunctivitis (3-4).
A study from Tuscon, Arizona, USA, concluded that Mulberry pollen is an important allergen associated with asthma and allergic rhinitis in children raised in a semiarid environment (5). In the tropical area of Caracas, Venezuela, Mulberry tree pollen was shown to be a frequently encountered aeroallergen (6).
Further studies, including from Spain and India, have shown Mulberry tree pollen to be an important aeroallergen (7-13). In a study of 30 patients in Santander, Spain, aged between 13 and 69 years, who suffered seasonal rhinoconjunctivitis symptoms and who had always lived in the area, it was found that 27% tested positive to Plantago, 20% to Quercus, and 13% to Mulberry tree pollen (14).
Mulberry pollen has also been recorded in the atmosphere of Didim, in southwestern Turkey (15). In a study conducted in the city of Heraklion, located in the center of the northern shore of the island of Crete, pollen from Moraceae
was the seventh most prevalent pollen recorded (16). In a study of the pollen spectrum in La Plata, Argentina, 79 pollen types were represented. The most prevalent 10 pollens included pollen from Mulberry tree (17).
Airborne contact urticaria due to Mulberry pollen has been reported. (18)Other reactions
Asthma and allergic rhinitis as reactions to the fruit of the Mulberry tree have been documented (19). Mulberry leaves have hypoglycaemic, hypotensive, diuretic and hypolipidaemic effects in diabetic patients (20).
The tree’s unripe fruit and milky sap are reported to result in stomach upset and hallucinations, but this is not substantiated by all authors.
Compiled by Dr Harris Steinman, firstname.lastname@example.org
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Kesava Reddy G. Effect of mulberry (Morus indica L.) therapy on plasma and erythrocyte membrane lipids in patients with type 2 diabetes.
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