Plant Scout

Flowery trees.

As a nurseryman, I am occasionally asked: “What’s an attractive small tree that grows quickly and has lovely flowers?”

That’s a short list, but one very fine candidate is the Mediterranean tree Vitex agnuscastus. Now, I’ve applied a very broad definition to the word “tree,” because this lovely specimen is actually a large bush that can be pruned to be more tree-like. In fact, it is better known in the gardening world as a chaste tree (more on that common name in a moment). Most trees are, of course, slow growing, but this multi-branching tree establishes quickly and will get to a good size even in its first year. Mature trees top out in the 10- to 20-foot range, depending on how they’re pruned.

The first thing people notice about it is its lovely purple flowers. Plants form long cones of lilac flowers that resemble those found on buddleja (butterfly bush). When mature plants are in full bloom the show is spectacular. Each cone, roughly 10 to 12 inches long, comprises dozens of ¼-inch open-faced flowers, much beloved by hummers, butterflies and bees. Dark green elliptical leaves provide a verdant backdrop for the summer-blooming show and look good the rest of the year. The leaves also exude a pleasing woodsy fragrance when crushed.

Chaste trees are versatile plants. They are showy enough to feature as a focal point in a sunny spot; when not in bloom, they blend in with Mediterranean planting schemes. They are an excellent addition to a pollinator garden, especially given that they grow, mature and bloom fairly quickly. Bees are especially drawn to the flowers. Given how cold-hardy and durable the trees are, you can also use them as a privacy screen or to line a driveway. You can also force a second bloom in late summer by removing the first flush of blooms as soon as they fade.

In reference to my opening comment, the compact nature of these trees means you can tuck single specimens into a relatively small space. Pruned hard, the trees become a dense, multibranching large shrub. They thus make great patio trees and, given a large enough container, can live happily within it for many years.

As to its name: Vitex is derived from the Latin vieo, meaning to weave or to tie up, a reference to the use of Vitex agnuscastus in basketry. The idea (probably erroneous) that this plant promotes chastity led to the castus part of its species name and its main common name (Chaste tree). As to its other common name — Monk’s pepper — that remains a bit of a mystery.

Earl Nickel is an Oakland nurseryman and freelance writer. Email: food@sfchronicle.com

The chaste tree is a fast-growing bush, Vitex agnus-castus, that can be pruned into a flowering tree.