Black Mulberry is not indigenous to this country and will not propagate by itself here, but is planted in parks, gardens and towns. It was imported into the UK in the hope that silk-worms would proliferate on it, but they like White Mulberry (Morus alba), not Black Mulberry!

The flower spike is yellowish green and appears in May. The red fruits go dark-purple almost black when ripe in high summer. They are edible when ripe, but slightly poisonous when red due to the presence of 1-deoxy-nojirimycin. The dye within can stain carpets and clothing.

POLYHYDROXYLATED PIPERIDINES 1-deoxy-nojirimycin (or DNJ) is a glucose analogue containing a nitrogen atom in the ring instead of an oxygen atom, as such it is a polyhydroxylated piperidine, an alkaloid by definition. (Nojirimycin is shown alongside for comparison only). DNJ is found in Red, Black and White Mulberry leaves and roots. It is a potent α-glucosidase inhibitor and is present in the milky sap which weeps from broken leaf stems and in the unripe fruits. DNJ can cause mild hallucinations, nervous stimulation and an upset stomach. It is absent from ripened fruits. The roots have been used to treat tapeworm. Research suggests it may be a suitable pharmaceutical for the glycaemic control of glucose for diabetic patients with impaired glucose metabolism. Some other polyhydroxylated piperidines are present in Spring Squill.