Ask Mr. Smarty Plants

You are actually talking about two species of the Ilex genus, Ilex decidua (possumhaw) and Ilex vomitoria (yaupon). As you might guess from the Latin name "decidua," the first species is deciduous. However, as they mature, these plants are covered with gorgeous orange-red berries all winter long, and are beautiful even bare of leaves. You say that the plants were in your yard when you bought your house, which means they might have had berries previously. The problem is, members of the Ilex genus are dioecious; that is, only the female bushes have berries, but there must be a male of the same species and blooming at the same time within about 40 feet of the female in order for the female to have berries. Bees are the pollinators, and sometimes will pollinate a plant grown in a yard with pollen they have gathered in the "wild" or in some other yard. 

So, there are two possibilities, all your shrubs are male or they are female, were purchased and planted with berries on them, and no male of the same species is in the area. The second is the strongest possibility, as nurseries commonly carry only females of berry-producing plants, because that is what everyone wants. The plants were probably shipped by a grower to the nursery where they were purchased after they had been pollinated and were showing berries. It is very difficult to differentiate between male and female bushes when they are not berrying, so the nurseries will sometimes tell you that "yaupons all have berries," as demonstrated by their plants on sale, which are all females. To make things even more complex, most commercially available yaupons are propagated vegetatively, by cloning, and all are cloned from female plants. 

If the yaupons in your yard are deciduous, you have Ilex decidua (possumhaw), which indeed are a great source for attracting birds. If you go to the nursery to buy some more, they will no doubt have berries on them, so they are female, too. You will have to do some detective work, and insist that the nursery find a couple of male plants (one or two will take care of pollinating a lot of females) of the same species. The growers, at least, have to have had males in the growing area for the two or three years the plants were being readied for shipment and sale, so that they would indeed have berries.

Ilex decidua

Ilex decidua

Ilex vomitoria

Ilex vomitoria