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Ilex verticillata

Winterberry or Michigan Holly

(Aquifoliaceae - Holly Family)

Form

• medium-sized ornamental shrub
• slowly maturing at about 8' tall by 8' wide under urban conditions, but larger in the wild
• upright oval to spreading rounded growth habit
• slow growth rate

Culture

• full sun to partial shade
• best performance occurs in full sun in acidic, organically-enriched, moist to wet soils, but it is somewhat adaptable to soils that are occasionally dry; chlorosis and stunting will occur in alkaline pH soils
• cultivars are propagated by rooted stem cuttings, while the species forms in the wild spread by seeds or suckers
• Holly Family, with occasional leaf spot being the only minor disease, and wildlife feeding (especially birds and deer) on the ripened fruits being the only pests
• commonly available in container or ball and burlap form
• plant one male plant (of the appropriate flowering time) in close proximity to three to five female plants, to ensure good pollination and subsequent fruit set

Foliage

• shiny dark green, deciduous, alternate, elliptical, and serrated
• a distinctive reticulate branching pattern of the veins occurs, with the outermost "shell" of veins being connected in an irregular oval shape, parallel to and very close to the serrated leaf margin
• chlorosis can occur during the growing season in alkaline soils, resulting in foliage that is medium green or chartreuse, while fall color is green, chartreuse, or purplish, and ornamentally ineffective

Flowers

• creamy-white and small, dioecious, occurring in early- to mid-June in the leaf axils from the new season's growth, and while noticeable up-close, they are ornamentally insignificant
• female plants have flowers with a distinct green miniature "knob" in the center (the immature ovule), while male flowers are loaded with yellow anthers (the pollen-bearing structures)
• like Blue Hollies, Winterberry male plants need to be carefully matched with female plants (mismatch of blossom times by even one week will result in poor to non-existent pollination and little or no fruit set on female plants); in many cases, the male plant is simply labeled "early" or "late" in reference to its relative bloom time
• if a large landscape planting of this species exists, and little or no fruit production occurs year after year, then buy both an early male and a late male, plant very close by, and observe if fruit production dramatically jumps

Fruits

• green ellipsoid immature berries emerge on female shrubs in early Summer, being sessile on the stems, becoming rounded, and maturing to attractive red berries in late August to early September, forming an outstanding contrast in late Summer and early Autumn against the dark green foliage
• berries persist well into Winter (if not eaten by wildlife) and are very showy due to their red coloration on the bare stems, although they will darken in color as the Winter progresses
• the red berries (cultivars are bright red, dark red, orange-red, gold, or lemon-yellow) are extremely effective when contrasted against background snow or when reflected in nearby bodies of water
• if female plants are sited in relatively dry soils, berry size (and subsequent ornamental appeal) will be maximized by irrigation during dry periods in July and August

Twigs

• purplish-brown on young stems in Winter, becoming gray with age
• on mature plants with spreading branches (as opposed to the upright habit in youth), the stems and branches will weight down heavily with berries
• mature plants will become leggy, but at the same time will sucker from their surrounding roots, forming broad colonies, especially if sited in permanently moist to wet soils in a group or mass planting

ID Summary

• dark green shiny leaves with a reticulate (net-like) branching to their veins, with the leaves becoming deciduous in mid-Autumn (a "deciduous holly"), bright red berries on female plants from late Summer through mid-Winter, a suckering growth habit at maturity to form broad colonies in a group or mass planting, and best performance in moist to wet, acidic soils characterize this very showy representative of the Hollies

Function

• most effectively used in a group or mass planting, found at entranceways, along borders, as a deciduous screen, in wet naturalized areas, and excellent at the very edge of bodies of water

Texture

• medium-fine texture in foliage and when bare
• open density in foliage and when bare

Assets

• showy red berries from late Summer through mid-Winter (on female plants)
• wet-site tolerant
• berry-laden stems can be cut for long-lasting indoor arrangements in Winter

Liabilities

• female shrubs (which bear fruit) require male pollinators in Spring
• require acidic soil for healthy growth and flower/fruit production
• slow growth rate
• root suckering with maturity, forming colonies (this is an asset in naturalized sites, or where erosion control is desired)

Habitat

• zones 3 to 9, in watershed areas or with roots submerged in bodies of water
• native to eastern North America

Variants

• many female cultivars exist, with some being hybrids of Ilex serrata (Fine tooth Holly) and Ilex verticillata; their required male pollinators are noted for their early (E), middle (M), late (L), or very late (LL) season of bloom, with the best pollinator(s) in bold:
  • Ilex verticillata 'Red Sprite' (also known as 'Nana' or 'Compacta') - very large, bright red fruits are borne in profusion and are very Winter persistent on this most compact of all cultivars, to 4' tall and 4' wide (E, M, and risky L)
  • Ilex verticillata 'Shaver' - very large, bright red-orange fruits are more flattened that other cultivars, borne in profusion and very Winter persistent, to 6' tall and 6' wide (E, M, or L)
  • Ilex serrata x Ilex verticillata 'Sparkleberry' - bright red fruits are borne in profusion and are very Winter persistent, to 12' tall and 10' wide, but not fruiting heavily when very young (M, L, or LL)
  • Ilex verticillata 'Winter Gold' - a sport of 'Winter Red', having pinkish-orange fruits that transition to gold, to 10' tall by 10' wide (M, L, or LL)
  • Ilex verticillata 'Winter Red' - bright red fruits are borne in profusion and are very Winter persistent, to 8' tall and 8' wide, by far the most popular cultivar (M, L, or LL)
• male pollinators:
  • Ilex serrata x Ilex verticillata 'Apollo' - new growth is bronzed, a late season (L) blooming large shrub, to 12' tall by 12' wide
  • Ilex verticillata 'Jim Dandy' (formerly known as 'Dwarf Male') - an early season (E) blooming compact shrub, to 5' tall by 5' wide
  • ([Ilex serrata x Ilex verticillata] x Ilex verticillata) 'Raritan Chief' - a mid-season (M) blooming spreading shrub, to 7' tall by 12' wide
  • Ilex verticillata 'Southern Gentleman' (unfortunately with the now-confusing but prior name of 'Early Male' [since seed-grown seedlings used in years past bloom later in June, and this male preceded them in floral emergence]) - a very late season (LL) blooming average-sized shrub, to 8' tall and 8' wide

Purpose

• Winterberry is a deciduous shrub with extremely attractive red fruits that persist into Autumn and Winter.

Summary

• Ilex verticillata is known as one of the best deciduous shrubs for ornamental red winter fruits, native to (and thriving in) wet sites containing organic soils with an acidic pH.

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