The Fruitless Mulberry tree is probably one of the best trees around when it comes to producing shade.
They are a very fast growing shade tree with a large spreading head. They take the dry desert heat and full sun very well.
Heavily planted in the mid 1900's as shade trees in many Southwestern towns. Today, it's really hard to find one for sale in a local nursery. This is because of the tree's allergy producing catkins.
Although the tree bears no fruit, these pollen-laden catkins appear on the tree in early spring, stay for two to three weeks and fall to the ground.
Most people with alergies are highly alergic to the pollen and suffer greatly because of these trees.
I would not suggest planting a Fruitless Mulberry in a rock landscape, as it is almost impossible to blow the catkins out of the rocks.
The Mulberry tree also has surface root issues, if your septic tank, swimming pool, sprinkler system pipes or any other water source happens to be nearby, these roots will search it out, lifting and cracking sidewalks that happen to be in their path.
Still, a great shade producing tree for the desert Southwest landscape.