From birdandhike.com: "White Mulberry (Morus alba) is a fast-growing deciduous tree that is native to China, but is widely cultivated and sometimes naturalized in the US. The species grows to some 60-ft tall, has large, green, sometimes dissected leaves, and produced huge amounts of pollen and fruit. Because of pollen allergies, the tree is considered a pest in some areas (not legal to plant in Las Vegas), but the fruit is relished by desert and migrant birds. Even normally insectivorous birds (e.g., Western Kingbird) feast on the fruits during spring migration. On young trees, the leaves are long and deeply lobed, but on older trees, the leaves tend to be shorter and unlobed with serrate margins. The flowers are borne in male and female catkins, usually on separate trees. Fruits look like 1-inch long blackberries; starting white and maturing to purple and black." With this information, it has given me insight on this particular kind of tree that I see often in parks, and I now understand why it is so widely used, as it is a fast growing tree that can provide a lot of shade, which would be helpful here in our desert climate.