Winterberry; Black Alder, Canada Holly, Coralberry, Fever Bush, Michigan Holly (Ilex verticillata)
Mature Size - (3-12′ x 3-12′) Occasionally will grow taller.
Shape and Form - Deciduous shrub with an upright-rounded habit. Dense branches grow in a zig-zag pattern.
Growth Habit - Slow growth rate. In the wild, it often suckers to form large thickets or colonies.
Leaves - Elliptic to obovate, toothed, dark green leaves (2-3” long). Fall color is usually negligible, but in some years leaves may turn attractive shades of maroon. A deciduous holly.
Flowers - Relatively inconspicuous greenish-white flowers appear in the leaf axils in late spring.
Fruit/Seeds - Flowers, if properly pollinated, give way to a crop of bright red berries (1/4” diameter) in late summer to fall. Berries are quite showy and will persist throughout the winter (hence the common name) and often into early spring. Berries provide considerable impact and interest to the winter landscape, and are of important wildlife value to a number of species.
Bark - Stems are slender, angled, olive-brown to purplish-brown. Glabrous or finely pubescent, and lenticelled. Stems develop onion-skin effect in second year, and turn grey and smooth with maturity.
Region - USA native. Native to eastern North America, down to Florida. Heaviest population densities in New England to Great Lakes region, and southeastern Canada.
Habitat/Growing Conditions - Typically occurs in swamps, damp thickets, low woods and along ponds and streams. Easily grown in average, acidic, medium to wet soils in full sun to part shade. Adaptable to both light and heavy soils, but prefers moist, acidic, organic loams. Good tolerance for poorly drained soils including wet boggy or swampy conditions. Will tolerate shade, but more sun means more fruit.
Plant Community - Red Maple Swamp
Eco-indicator - Facultative wetland species.
Other info - See Ilex verticillata ‘Afterglow’
Winterberries are dioecious (separate male and female plants). Only fertilized female flowers will produce the attractive red berries that are the signature of the species. Generally one male winterberry will be sufficient for pollinating 6-10 female plants. Flowers appear on new growth.
The fruit of Winterberry is eaten by small mammals and more than 48 species of birds. The leaves and stems of Winterberry are not a preferred source of browse, but moose, whitetail deer, cottontail rabbits, and snowshoe hare do utilize this plant.
Current Nursery Status and Availability - Species itself is relatively uncommon in nursery trade, as most retailers opt to carry a number of well-preferred cultivars. A wide variety of cultivars and varieties exist, all of which have varying degrees of popularity and availability. Dirr lists several cultivars of this species in his 6th edition woody plants manual, some of which are listed below.
'Afterglow' - This form features glossy green leaves that are smaller than typical. It is compact growing (to 10' tall and wide) with large orange-red berries maturing to orange. It is best pollinated with 'Jim Dandy'.
'Aurantiaca' - An unusual form, this cultivar produces orange-red fruit that fade to orange-yellow. These fruit are less persistent than most red fruited forms, plus they may discolor easily. It blooms early, thus it is best pollinated by 'Jim Dandy' or other early- flowering male selections. The habit is around 5' tall; slightly larger than 'Red Sprite'. 'Chrysocarpa' (correctly I. v. f. chrysocarpa) is a naturally-occuring yellow-fruited form.
'Cacapon' - This plant grows to 5' tall, possible more. It is similar to 'Afterglow', but more upright in growth. It is heavy-fruiting, with true red fruit, plus the leaves are textured and dark green and glossy. Use 'Jim Dandy' as a pollinator.
'Jim Dandy' - A slow-growing, early-flowering dwarf male clone, this cultivar is useful as a pollinator for early-flowering female clones such as 'Afterglow', 'Aurantiaca' and 'Red Sprite'. It grows to about 5' tall.
'Red Sprite' - A very popular, award-winning form, this dwarf female clone matures at only 3' to 4' tall. The habit is pleasantly mounded. Early blooms produces numerous, very large red fruits which persist well in the winter. This USDA release is widely considered to be one of the best winterberries. Use 'Jim Dandy' to pollinate. 'Shortcake' is similar, but larger (to 5' tall), with smaller fruit.
'Shaver' - An early-flowering form (use 'Jim Dandy' to pollinate), this plant produces orange-red fruit and glossy leaves on an upright, 5' tall shrub.
'Southern Gentlemen' - This plant is a late-blooming male pollinator for 'Winter Red', 'Winter Gold', 'Capapon', 'Shaver', 'Sparkleberry' and other later blooming female clones.
'Stoplight' (aka 'Hopperton') - This is a newer selection with large, deep red fruit and glossy foliage on a 8' tall plant. 'Jim Dandy' should be used as a pollinator.
'Sunsplash' - A very unusual and rare form, this plant sports leaves irregularly mottled and marked with yellow. The variegated leaves are complemented by red drupes on this female clone.
'Winter Gold' - A branch sport of 'Winter Red' (Winter Red), this plant features unusual pinkish or golden-orange fruit. It grows to around 8' tall and wide. The blooms come late, so it requires a late-blooming male as a pollinator (such as 'Southern Gentleman'). The leaf color is a lighter green than 'Winter Red'.
'Winter Red' - This popular form is widely accepted as one of the best winterberries. It forms an upright, rounded shrub to around 8' tall with dark green foliage. The bright red fruit are borne in profuse quantities and they persist into winter consistently.
Ilex verticillata x Ilex serrata hybrids: These forms exhibit more vigorous growth than Ilex verticillata cultivars, plus the new leaves emerge purplish. In addition, the fruit discolor by late winter. They are becoming more popular in commercial trade and cultivation.
'Apollo' - This is a male clone useful as a late pollinator for 'Sparkleberry' and 'Winter Red'. The new growth is burgundy-red, and the habit is ascending-upright with a final height of 10' to 12' tall. A U.S. National Arboretum introduction.
'Autumn Glow' - A selection out of Rutgers University, this plant is dense-growing to 10' tall and wider. The red fruit persist well, but may discolor. Reports vary concerning fall color, which may include yellow and orange shades.
'Bonfire' - Most notable for its profusion of small red fruit early in the season, this selection fruits at an early age and holds the fruit well. It will reach 12' tall and wide with a mounded habit. 'Apollo' should be used as its pollinator.
'Harvest Red' - This plant produces deep red, large fruit on a 10' tall and 15' wide plant. The leaves may color yellow in fall. Use 'Raritan Chief' to pollinate.
'Raritan Chief' - This is a male clone used to pollinate many deciduous holly hybrids, as it flowers over a long period. It may reach 12' tall and features attractive glossy, light green foliage.
'Sparkleberry' - This award-winning, popular selection is common in the trade. It ultimately reaching 12' tall and can become somewhat leggy at the base due to its upright growth habit. The main attraction are the abundant red fruit that are medium-size and persist well, often until spring. Use 'Apollo' to pollinate this U.S. National Arboretum introduction.
http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=d440
https://plants.usda.gov/factsheet/pdf/fs_ilve.pdf
https://plants.usda.gov/core/profile?symbol=ilve
http://www.hort.uconn.edu/plants/detail.php?pid=221
https://gobotany.newenglandwild.org/species/ilex/verticillata/
Dirr - “Manual of Woody Landscape Plants”
Wessels - “Reading the Forested Landscape”
