The Friends of the Wildflower Garden, Inc.

Trees & Shrubs of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States


Common Name
Winterberry (Black Alder)


Scientific Name
Ilex verticillata (L.) A.Gray


Plant Family
Holly (Aquifoliaceae)

Garden Location


Prime Season
Early Summer flowering, red drupes can be persistent into winter



Winterberry is a large shrub, 6 to 16 feet high, forming red 1/4 inch drupes in the fall, assuming that there are both male and female plants nearby as the sexes are separate (i.e. dioecious). It takes about 3 years for seedlings to develop their flowers.

The bark is conspicuous with a thin brown outer surface with whitish patches (lenticels).

Twigs are slender, green on new growth, then brownish, with scattered light colored lenticels. Buds are small and emerge above old leaf scars where there may be a small persistent stipule on the side of the leaf scar.

The leaves are sharply toothed, stalked, 1 1/2 to 4 inches long, lance to ovate shape, pointed at the tips, deep green in summer, hairy on the underside, and turning yellow in autumn.

Flowers: The small greenish-white flowers with 5 to 7 petals form clusters in the leaf axils in early summer in our climate zone. Male and female flowers are on separate plants. Both are stalked and same size, however, the female flowers have one to three flowers in the cluster and the male flowers have two to ten; only at this time can the sexes be determined.

Fruit: The drupes are very attractive and are eaten by about 50 species of birds, HOWEVER, the fruit should not be eaten by humans as it is a purgative. Inside is a hard nutlet.


Habitat: In the landscape Winterberry should be planted in areas that receive good moisture but marsh soil is not required. A large amount of sun is helpful. It can grow to 15 feet high with dense branches. Plants can be developed from rooted stem divisions and stem cuttings.

Names: The genus Ilex denotes 'holly' and comes from the Latin name for the Holm (or Evergreen) Oak (Quercus ilex). Linnaeus applied it the the hollies. The species name verticillata, means 'whorled' or 'forming a ring around an axis' and refers to the flowers and the drupes appearing as to surround the twig.

The author names for the plant classification are: First to classify was '(L.)' which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. His work was amended by ‘A.Gray’ which refers to Asa Gray (1810-1888), American botanist, Professor of Natural History at Harvard and instrumental in unifying plant knowledge of North America and author of Gray’s Manual - Manual of the Botany of the Northern United States, from New England to Wisconsin and South to Ohio and Pennsylvania Inclusive. He was a student of John Torrey and became his assistant. His first book, Elements of Botany was the first text to use the new Natural System of classification. He and Torrey collaborated for the remainder of their lives.

Comparisons: This is the only native holly growing in Minnesota. In the fruiting stage it could be confused with Glossy Buckthorn (Frangula alnus) when the buckthorn berries are red, but the Glossy Buckthorn leaves are more oval and do not have teeth. The flowers are also different.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

Winterberry shrub Winterberry fruit

Above: In perfect growing conditions of sun and adequate moisture, Winterberry produces an abundance of fruit.

Below: 1st photo - A twig with male flowers - note how they cluster and appear to encircle the twig - hence the species name. The blooms appear in late June to early July and the red fruit shown here (2nd photo) in September.

Winterberry flowers Winterberry fruit

Below: 1st photo - Leaves are dark green on top, tapered on both ends and on a short stalk. 2nd photo - Each flower has a short stalk. The calyx is light green with rounded lobes. The new twig shows the conspicuous light colored lenticels which remain as the twig ages.

leaf calyx

Below: 1st photo - Flowers are greenish-white with 5 to 7 petals. 2nd photo - A small cluster of male flowers. Note the hairy underside of the leaf and the sharp marginal teeth.

Winterberry flower detail Winterberry leaf underside

Below: 1st photo - The conspicuous white patches on the brown older stem bark (expanded lenticels). 2nd photo - A small thorn-like persistent stipule remains on either side of a leaf scar, below the new buds.

Winterberry bark lenticels Winterberry leaf scar

Below: 1st photo - In late fall, remaining drupes loose their bright red color and the twigs (2nd photo) turn from green to a brown.

Winterberry fall fruit Winterberry twig

Below - For comparison: The fruit of Glossy Buckthorn in the red stage before turning black. Green and red fruit can resemble Winterberry. The leaf is more oval and without teeth. Shrubs can be of similar size.

Glossy Buchthorn red fruit


Notes: Winterberry is indigenous to the Garden area. Eloise Butler catalogued it on April 29, 1907. There are numerous additional acquisitions by Eloise Butler. Plants were obtained from Solon Springs, WI on Oct 2, 1913; 2 from Kelsey's Nursery in Pineola N.C. on Oct 6, 1917; from Stanchfield, MN on Sept. 6, 1921 and from Round Lake, MN on Sept. 24, 1924. Winterberry was listed on Martha Crone's 1951 inventory of Garden Shrubs. She planted specimens in June 1933, '35, '37, '47 and '56. Ken Avery planted some in 1963. All but one of these died back at sometime as when Gardener Ken Avery retired, the Friends of the Wild Flower Garden had this species planted in his honor. It was Mr. Avery's choice of plant - "Minnesota Holly" as he called it. Gardener Cary George reported that at that time only one plant was left in the marsh area and while it took him some time to find the correct species, he and Friends' member Joyce Smeby and her family planted 3 of them in 1987 and additional plants in 1989, and the existing specimens are presumably these; then Susan Wilkins added more in 2019.

This is the only Holly native to Minnesota, it is found in the more moist areas of the eastern half of the state from the metro area north and in a few counties in SE Minnesota. It is hardy in all zones. In North America it is native to all states along and east of the Mississippi River and to those Canadian provinces northward of that.

Medicinal Lore: There is literature about the use of the bark and fruit for medicinal purposes. Mrs. Grieve (Ref.#7) has a good description. The bark contains tannin, two resins and a bitter principle. A decoction was prepared by boiling the bark for use as a tonic, astringent and a cathartic. Fruits, when eaten, are cathartic (purgative).

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

graphicIdentification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.