Holly (Ilex) has been associated with winter celebrations since at least Roman times when it was a feature of Saturnalia, a week-long party around the winter solstice in December. In later centuries, holly’s evergreen leaves and persistent red fruit were entwined in other symbologies including those of the Druids and Christians; holly has been a staple of Christmas celebrations since the early Middle Ages.
There are at least 400 Ilex species [pdf] worldwide, but the Romans (and later celebrators) cut branches of English holly (Ilex aquifolium), an evergreen species with a wide native range from the British Isles through western and southern Europe, southwestern Asia, and northern Africa. English holly forms a small, dense, upright shrub or tree and is noted for its stiff, spiny, glossy deep green leaves and bright red berrylike fruit (hollies are dioecious–male plants provide pollen and fruit are borne on female plants). In North America, English holly grows best in the moderate climate of the Pacific Northwest, where commercial growers in Oregon, Washington, and British Columbia produce much of the world’s supply of cut English holly branches, including both green and variegated-leaf types.
English holly has limited cold hardiness (USDA Zone 6b or 7) and poor heat tolerance, but a similar looking species, American holly [pdf] (Ilex opaca, Zone 5), is much more adaptable. Its native range runs from Massachusetts south to Florida and west to southeastern Missouri and eastern Texas. American holly forms a dense, pyramidal, small to medium-sized tree. Its evergreen leaves are similar in form to English holly but generally lack that species’ glossiness. The showy fruit (drupes) are red, and there are also yellow-fruited forms.
The foliage of evergreen hollies certainly provides year-round landscape interest, but my favorite hollies are the winter-bare deciduous species. When the leaves drop from female specimens of these multi-stemmed shrubs a spectacular display of bright red fruit is revealed. The Arboretum collection holds a number of deciduous hollies including North American natives winterberry (Ilex verticillata) and possumhaw (Ilex decidua) as well as the Japanese species Ilex serrata. Look for winterberry cultivars such as ‘Red Sprite’ and ‘Winter Red’ in the Leventritt Shrub and Vine Garden.