In the landscaping of my region (New England, U.S.), holly shrubs are more commonly found than the corresponding tree form. But Ilex species span quite a variety of sizes, shapes and, consequently, uses. Indeed, one cultivar, 'Helleri,' can function as a ground cover. But at the other end of the spectrum, Ilex opaca commonly stands 50 feet tall; an Ilex towers over my neighbor's two-story house. Nellie Stevens is a popular tree-form type in the American Southeast.
Holly shrubs (and trees) are truly iconic plants. Since most are evergreen, they're a boon to the winter landscape. This same quality -- pregnant as it is with symbols of hope and rebirth -- helps account for why Ilex is one of the plants of our Christmas traditions (especially Ilex aquifolium). Have you ever heard the Christmas carol, The Holly and the Ivy? Or how about the delightful tale from pagan times of the Oak King and the Holly King in connection with the winter solstice?
The excitable Robin from the Batman comics might well have cried "Holy Ilex, Batman!" upon hearing all of this. And if you're a landscaping enthusiast, there's no reason why you, too should not be excited about holly shrubs. About the only downside I can think of is that, given the mild toxicity of the berries for humans, dogs and cats (but birds like them just fine), Ilex species can be listed as poisonous plants.
Let's look at a few examples of holly shrubs below, so that I may impart to you some idea of their diversity -- both in appearance and in landscaping usage.
So what's "blue" about Blue Princess holly shrubs? That epithet is used to indicate the dark color of the plants' leaves. "Dark green" would probably be more accurate, but maybe "blue" sounded better to the marketing folks (you should never underestimate the impact marketing has on plant names!).
Blue Princess sports the classic red berries with which we associate holly shrubs. These add to the winter interest furnished by the bush, provided that you can keep the wild birds from eating them (I protect mine with a netting called "BirdBlock"). Along with the plants' attractive foliage, these red berries make the plant sufficiently pleasing to the eye to warrant using it as a specimen plant. To ensure berry production, you'll want to provide a Blue Prince as a pollinator.
When you see Ilex crenata as the scientific plant name on a plant label, you know you're dealing with one of the Japanese holly shrubs. In this article, I introduce you to one that could easily pass for a boxwood at a distance (or even up-close if you do not know what to look for).
Unlike Blue Princess, this bush bears black berries (try to say that fast three times!). But as with all types of Ilex, you need a male and a female if you want the pleasure of a berry crop. You see, Ilex bushes are dioecious.
Like the Hetz cultivar described above, 'Sky Pencil' is an Ilex crenata (Japanese holly shrub). Also like Hetz, it bears tiny leaves and black berries. But the similarities end there.
The cultivar name of this plant gives a good indication of its signature feature. This is a bush that is narrow, relative to its height. In horticultural terms, such a plant is said to have a "columnar" plant form. This feature makes Sky Pencil popular in landscaping around front entries; such columnar plants effectively frame an entrance. Alternatively, another use for this holly shrub in foundation plantings is at the corners of a house (for a "bookend" effect).
When a bush in our landscaping has dropped its leaves, it's seldom a cause for celebration. Generally, we tolerate a plant's being deciduous, but we prefer it when it's clothed in foliage.
Winterberry, however, furnishes an exception to the rule. These deciduous holly shrubs are grown almost exclusively for their displays of red berries. And why would you want their plain-Jane leaves to be obscuring the view of those berries, right? Winterberry is at its prettiest after it has lost its leaves.