A couple of years ago, I was designing a garden for someone who was interested in creating a nature-friendly landscape in her backyard. One of the plants that I chose was our native Inkberry shrub - Ilex glabra "Shamrock". The dark colored berries (actually drupes) are a valuable food source for birds and small mammals in late winter. However, lo and behold, the five shrubs I planted produced no berries, even after two years. It suddenly occurred to me that (duh!) since Inkberries are dioecious (separate male and female plants), the females needed a male for polination! Why didn't I think of this before? Thus started my quest for a male inkberry.
It seemed to be an easy enough task...just go back to the nursery and buy a male plant. Not so easy, as it turns out. It seems that Inkberries are primarily hybridized and sold for their foliage value - bright shiny evergreen leaves - and not so much for their fruit. Most nurseries don't even sell males - or even know which Inkberry is a male. A check of the Ilex glabra section in Dirr's Manual wasn't much more help...of the 20 odd cultivars listed, nine are labeled as being female; eleven have no gender mentioned or have an undetermined sex. A recent internet search continued the confusion: the cultivar Nordic 'Chamzin' is listed in Baileys Nursery catalogue as being a male; Weston Nurseries lists 'Chamzin' as having black berries. Sylvan's Nursery doesn't list the sex of any of their Ilex glabra cultivars; interestingly enough all of the Ilex verticillita cultivars are clearly labeled as male or female.
I mentioned my confusion to Sue Gordon at URI, and she initially thought that males would be present in sufficient quantity in nature to provide the needed polination. However, she has come to the conclusion that the nursery industry, and the native plant nursery industry in particular, needs to pay closer attention to this. She has started propagating male plants; and is making an effort for other nurseries to join in the cause.
The flowers on all Ilex species are small, fairly inconspicuous and somewhat similar which probably leads to the confusion. Male flowers, it seems, occur in clusters (see photo above) while the female flower is generally found singly on a stem. Other than that, the only real way of identifying a female is the presence of berries.
