What is this winter beauty doing in July?
Updated: Jul 29, 2021
Winterberry holly (Ilex verticillata), bearer of those vibrant winter berries that hold on long after the leaves have colored and fallen, is actually blooming now! Not noted for the showiness of its blooms, you must walk right up to the plant to spot the flowers. If you look carefully you might learn something new. Winterberry is diocious, meaning each plant is exclusively male or female, unlike monecious plants which have both male and female parts on the same plant and often the same flower. Biology basics tell us that pollen from the anthers (male flower part) lands on the pistil (female flower part) it makes its way to the ovary and the flower is pollinated. The ovary becomes the seed or the fruit, so in the case of winterberry holly, only the female plants can produce fruit.
Cultivars are sold as sexed plants with amusing names such as sparkleberry (female) and southern gentleman (male of course). But what if your labels have disappeared and you want to transplant your shrubs now, how will you know which are the males and which are the females? You can tell by examining the flowers closely. On the male flowers, the anthers are protruding from the center of the flower compared to the female flowers where the pistil is protruding. If you don’t have a hand lens, you can count the number of flowers in each cluster at the axil of a single leaf (where it joins the stem). Females will have from 1 to 3 flowers and the males will have more - many more. Anytime after flowering, you can look for the developing fruits to identify the females.
Winterberry hollies tends to sucker from the root, so now is a good time to visit your plants and look for suckers you might want to transplant. Remember the suckers will be the same sex as their parent. Follow the root sucker back toward the plant as far as you can and cut it through. Leave the sucker in place for a couple of months and transplant in September or wait until next spring. These may take a few years to reach fruit bearing age and contribute fully to the beauty and habitat of your winter garden, but you will have the satisfaction of creating more plants that have the fruiting characteristics you desire.