Common names for many plants can be a turn-off to potential customers; therefore I propose the common name morph over time into Spice Tree instead of chaste tree. The plant constantly emits a pleasant and distinct spice-like odor during the growing season. Brush a twig or a few leaves and release of the volatile oil increases. And, even when dormant, the odor remains sufficient to keep deer from feeding on branches or rubbing on large stems.
Vitex negundo is native to China, but is now considered “native” to a large area along the Silk Road through the near east to southern Europe. Vitex agnus-castus appears to have evolved from V. negundo. One hypothesis is that travelers packed Vitex seeds with goods to prevent damage from rodents.
Vitex is commonly described as a large shrub or small tree, and some are. However, extreme dwarfs, semi-dwarfs and small shrub forms are being developed that will fit into most landscapes. Growing thousands of seedlings in the field over eight generations is a substantial price to pay to get to the unique seedlings we are currently evaluating. But growth forms are only part of the improvements.
Vitex is another desirable shrub native to China hardy in zones 6 to 9. Vitex blooms on new growth beginning in early summer and with current seedling populations, many continuing until frost. Our original seed produced plants that flowered once in mid-summer, developed huge quantities of seed and flowered sparsely late in the season if at all. We now have flower colors ranging from near blue, to purple, pink, cream and white. Many seedlings now flower twice and some three times during the growing season with duration of each flower show ranging from 12 to 20 days or more.
Leaves are opposite and palmate leaf shapes range from three to five leaflets, 2 to 3 inches across and appear fern-like, to seven or occasionally nine palmate leaflets 6 to 8 inches across. Leaf shape on some seedlings is remotely reminiscent to marijuana (Cannabis sp.) but the foliage odor makes ID easy.
Vitex grows best in full sun, yet performs well with broken shade for a few hours. Vitex, like crapemyrtle, is best planted from containers during summer when soils are warmest. Also like crapemyrtle, we plant Vitex in any location available, poorly or excessively drained, sandy or heavy clay and they consistently do well. We plant Vitex in areas on the research farm nearest to adjacent woods that provide cover for large quantities of white tail deer. Deer do not bother Vitex and a missing twig or stripped off foliage or a rubbed larger plant has not been observed – not once. And, interestingly, Vitex is not bothered by insects. Large grasshoppers are commonly seen on the stems, but, no signs of feeding, which suggest the insect is using the foliage for cover. To date, and having grown many thousands of plants, we have not observed aphids, mites, thrips or other insects on the plants. There is, however, a virus common among seedlings that causes light colored blotches on leaflets, but, no distinguishable stunting or other problems. And seedlings free of virus symptoms are now the norm. The most widely grown cultivar is Shoal Creek, a large, vigorous plant with purple flowers.
Lacebark has news about release of cultivars of this tough and widely adaptable landscape plant. It will be worth the wait.