Black mulberry is not native to the UK - which surprises quite a few people. There are quite a few good specimens across Exeter in such places as Heavitree park, Rougemont gardens and by the side of the Cathedral green. There are three main groups of mulberry which are black, red and white and there are many cultivars about which can make identification quite tricky. Black mulberry is native to southwestern Asia and the Iberian Peninsula, however it's been in cultivation for so long nobody can be sure of it's natural range. The black mulberry was imported into Britain in the 17th century - mainly to try and feed silk worms. This didn't go to plan as the silk worms prefer the leaves of White mulberry - thankfully a lot of the old trees remain alive to this very day.
The two main reasons why Black mulberry was planted in the UK was for the edible fruit and as a food source for silk worms. As such you tend to find the older trees in old private estates, court yards and a handful of large parks. They are not suited as street trees due to the high amount of mess they create in the summer (fruit) and the autumn time (leaves). The Black mulberry tree is quite fast growing and can produce fruit from as young as 10 years of age. They typically grow up to heights of 12m so are considered small to medium sized trees. They tend to grow wider rather than taller. Of the three main types of Mulberry the Black mulberry is the smallest.
The leaves are usually 10 - 20cm long by 6 - 10cm in width with toothed edges
Black mulberry is a small to medium sized tree and is usually wider than it is tall
Black mulberry is a dark green coloured deciduous small to medium sized tree but it in some cases can grow as a large shrub. The trunk is usually quite with large lower branches - so this makes an excellent tree for climbing! The leaves are usually 10–20 cm long by 6–10 cm in width. They are downy on the underside whereas the upper surface is rough with very short, stiff hairs. The buds of the Black mulberry are quite large and distinct and make identifying this tree a lot easier in the winter.
During early summer the flowers are present - but are often hard to spot under the large amount of leaves
The fruit is a similar to a raspberry but will turn a dark purple before falling off the tree
A very interesting feature of Black mulberry is the flowers. Usually the trees are dioecious so the male and female trees are separate. However, this can change from year to year so an all male tree one year could be all female the next! In some cases it will be monoecious so will have both male and female flowers on the same tree. The male flowers are longer than the female ones and usually stand out a bit more. The flowers are greenish or creamy coloured and are arranged in short catkins designed for the pollination by wind. That being said I have seen plenty of insect pollinators on the flowers. As the female flowers mature into the fruit they change colour from light green to red and eventually a dark purple almost black colour. When the fruit begins to fall the ground is soon covered in deep reds, dark purple and black splatters - which is why they are not good street trees. Also they tend to drop a lot of fruit at the same time - so you have to be quick to pick them to avoid a lot of waste.
The bark is orange-brown and often gnarled with large burrs and fissures
The buds are large and dark reddish brown with a tip
Black mulberry requires full sunlight to grow to it's full potential so for this reason is usually planted as a centre piece. The root system is quite aggressive and will easily destroy drains and other underground resources - another reason why it is not suited as a street tree. When picking the fruit is almost impossible not to get stained with the deep red colours - so wear suitable clothing! The fruit is very good for you and contains lots of vitamins and minerals.