Let's make a catch-all thread for this genus. Likely best we start with a simple dichotomous key. I say this because looking at the data I have had V. negundo unknowingly. I have successfully grown: V. negundo, V. agnus-castus, and V. trifolia.
Botanical Key: Common Vitex Species in Bonsai
For...
Up for auction is a One-year-old cutting grown new variety of Vitex agnus-castus that I have identified and will be releasing. I'm calling it, Vitex agnus-castus 'corteza áspera' (rough bark in Spanish) as a tip of the hat to how well it performs in the Southwest. (It's also called Chaste Tree...