Bush or tree?

If you have seen a shrub covered with cone-shaped, lilac-blue flowers during recent weeks you have probably seen a Chastetree, scientific name Vitex agnus castus.
This bush, which can be trained as a tree, has many wonderful traits.
The first bloom period lasts for a few weeks, but additional blooms will appear later in the summer. 
If the old blooms are removed the new ones will appear more quickly.
The casual observer might think that this is Cannabis because the leaves are shaped similarly, but there is a world of difference.
In fact in medieval times, monks made potions of the berries to assist them in keeping their vows of chastity, the source of the common name.
The Chastetree may be planted in full sun or partial shade in soil that is well drained. After it is established, it does not require supplemental watering and is ideal in a Xeric landscape.
This deciduous plant blooms on new growth, so it may be pruned in the spring to keep the size you want.  If it is not pruned it can grow as tall as 20 feet and up to 15 feet wide. 
It tends to put on leaves later in the spring than most shrubs.
Chastetree may be purchased in containers at plant stores and can be propagated from cuttings taken in either the summer or winter. 
Low hanging branches can be layered by burying part of the limb in soil, held in place by a rock or brick. In the spring the branch can be cut off and planted at another location. 
Depending on the source you check, this plant came to the United States from China, India, or the Mediterranean.
It has been here since 1670.
Recently new varieties have been developed, such as ‘Montrose Purple,’ ‘LeCompte,’ both with purple blooms, and ‘Salinas Pink.’