Hollies are innately uncommon in California. Yaupon (holly), Ilex vomitoria, happens to be one of the least common. Ironically, because of its small leaves and dense growth, it is more tolerant to frequent shearing by maintenance gardeners who ruin other hollies. It can actually make a nice shorn hedge.
Hedged yaupon can eventually get up to the eaves of a single story. Unshorn plants can reach the eaves of a second story, and might display showy red berries about an eighth of an inch wide. The small and often randomly serrate leaves are only about half to an inch long, and maybe half an inch wide.
Seasonal color is as variable as the weather. Just as the many different spring flowers bloom differently every spring, and the autumn foliage color is different every autumn, the colorful berries and fruits that linger on many plants through winter respond to the weather. Then, the various birds and other animals that devour them do so at different times, and at different rates every year.
Pyracantha (or firethorn) is probably the most reliable for an abundance of brightly colored red berries. Old varieties with orange or even yellow berries are very rare, perhaps because they are comparably wimpy. Unfortunately, because they are so colorful, and also because they ripen before many of the migratory birds have gone, the berries often get eaten by birds soon after they ripen.
Berries of the various cotoneasters are not quite as colorful, and many ripen slightly later, so they are not so efficiently stripped by birds. Cotoneasters are now more popular than related pyracantha because there are so many varieties with so many different growth habits. Larger types grow into large shrubbery while prostrate types grow as ground cover. Cotoneaster also has the advantage of lacking thorns.
The native toyon can provide large clusters of similar red berries, but only if it is allowed to grow somewhat wildly. It is unable to bloom and subsequently produce berries if regularly shorn. Yet, even in the wild, toyon is unpredictable. Because damp weather can cause berries to rot before they ripen, toyon may be unproductive for many years, and then produce remarkably colorful displays of berries when least expected.
Hollies are the most familiar of colorful winter berries, but are not as colorful as pyracantha or the various cotoneasters because they are almost never provided with male pollinators that they require to develop fruit. Fortunately, their remarkably glossy and prickly foliage is appealing alone.
Flowering crabapples are grown for their impressively colorful pink, white or nearly red spring bloom, but some types also produce sparse and minute red, orange or even yellow crabapples that stay after the foliage turns yellow and falls. English hawthorn lacks the flower color of flowering crabapples, but has more abundant and colorful red or orange berries that linger into early winter after the foliage is gone, or at least until birds find them.
It is no coincidence that so many colorful berries ripen in autumn as migratory birds migrate south for winter. Such colorful berries are intended for both migratory and overwintering birds. Rodents and other wildlife are welcome to take what they want as well. Most colorful berries are bright red, to get the attention of birds and wildlife. They are a convenient ‘grab and go’ size, and abundant.
Plants who produce colorful berries are pleased to provide in exchange for the dispersion of their seed. It is an ingenious system. Everyone involved does what they do best. Plants produce their colorful berries to exploit wildlife. Wildlife exploits the berries. Seed within the berries survives digestion, and gets ‘deposited’ elsewhere. Most types of berry seed germinate best after digestion.
Colorful berries are popular in home gardens either to attract birds, or because they are delightfully colorful for autumn and winter. Of course, many that should remain colorful attract birds instead. Fortunately, birds are good sports, and often leave colorful berries long enough to blet (age). Then, polite birds consume the berries before they get messy, and ideally take their mess elsewhere.
Various hollies are famous for their colorful berries. However, not many hollies reliably produce many berries here. Because they are dioecious (of separate genders), commonly available female plants are fruitless without rare male pollinators. Fortunately, modern hollies are becoming available in conjunction with pollinators. Otherwise, the best colorful berries are of the Rosaceae family.
Firethorn is the most profuse and most familiar of the colorful berries through autumn and winter. A few species and cultivars of Cotoneaster can be almost as prolific, but with more subdued color and stature. Toyon is a related native species that performs well in unrefined landscapes. English hawthorn produces similar colorful berries, but develops into a small and gnarled deciduous tree.
Unfortunately, none of these colorful berries are notably edible. In fact, some are mildly toxic.