Glossy Buckthorn, Alder Buckthorn, Fernleaf Buckthorn, or Tallhedge Buckthorn

(Rhamnaceae - Buckthorn Family)

Form

• large foliage shrub for the species form (Glossy Buckthorn) and both cultivars below:
• 'Asplenifolia' (Fernleaf Buckthorn) matures at about 12' tall by 10' wide
• 'Columnaris' (Tallhedge Buckthorn) matures at about 12' tall by 3' wide
• upright vased growth habit for 'Asplenifolia', becoming upright rounded with age
• upright columnar growth habit for 'Columnaris', becoming upright oval with age
• medium growth rate in youth for all forms, becoming slow with maturity

Culture

• partial sun to partial shade for 'Asplenifolia'
• full sun to partial sun for 'Columnaris'
• both cultivars perform best in rich, moist, well-drained soils, but are somewhat adaptable to poor soils as long as they have adequate drainage
• propagated primarily by stem cuttings, although seeds readily germinate
• Buckthorn Family, with one notable long-term potential pest (root nematodes), one serious cosmetic leaf damage pest (Japanese Beetles), and one potential disease (stem cankers, caused by a fungus)
• commonly available, in both container and ball and burlap forms
• 'Asplenifolia' attains remarkable vigor and beauty when situated in moist, well-drained, rich soils with morning sun and afternoon shade; full sun and dry soils render this cultivar weak, with even thinner stems and smaller, faded green foliage
• 'Columnaris' does remarkably better in full sun as an isolated shrub (which almost never happens, as it is almost exclusively used as a hedge), because both of the potential pests rapidly spread and multiply in a monoculture mass planting situation

Foliage

• 'Asplenifolia' has alternate, medium to dark green, deciduous, narrowleaf foliage (about 4" long and 3/8" wide), with an irregular and wavy margin; the foliage canopy as a whole is very fine-textured and ferny in appearance (hence the common name)
• 'Columnaris' has alternate, glossy dark green, obovate to oval, deciduous foliage (about 3" long and 1" wide), with an entire margin, creating a dense canopy when combined with the numerous twisting stems

Flowers

• the creamy-green, miniature inflorescences emerge in May from the leaf axils of the new growth and attract numerous bees, but are ornamentally insignificant

Fruits

• pendulous berries hang from the leaf axils and undergo a color transition from green to red to black in late Summer, maturing in September and devoured by the birds
• the juicy black berries will stain sidewalks or automobiles nearby as they naturally abscisce or are dropped during feeding by the birds

Twigs

• thin, gray, and lenticeled, forming V-shaped branches in the vased canopy of 'Asplenifolia', but twisting and curling around themselves in the columnar canopy of 'Columnaris'

Trunk

• multitrunked, with the trunks spreading apart at the base of 'Asplenifolia' into a vased shape, but either upright or girdling each other at the base of 'Columnaris'
• both cultivars have trunks that become leggy with age (i.e., their lower twigs and foliage die from self-shading with maturity, exposing their "bare legs"), but in the case of 'Columnaris', this is especially noticeable and a great liability due to its normal usage as a visual screen

ID Summary

• 'Asplenifolia' has narrowleaf, "ferny" foliage and very thin stems on a vased-shape shrub, often found as a single specimen or in a small group planting, noted for its graceful appearance and ultra-fine texture
• 'Columnaris' has broadleaf foliage on a columnar shrub with twisting stems and self-girdling trunks, often planted as a linear hedge for its semi-formal, columnar screening effect (hence the common name), and becoming very leggy with age

USAGE

Function

• 'Asplenifolia' is used as a specimen or in group plantings
• 'Colunaris' is used in row plantings as an informal hedge

Texture

• 'Asplenifolia' has ultra-fine texture in foliage and when bare, and has an average density in foliage and when bare
• 'Columnaris' has medium texture in foliage and when bare, and has a thick density in foliage and when bare (except for the legginess at the bottom of the trunks)

Assets

• 'Asplenifolia'
  • ultra fine-textured "fernleaf" foliage
  • vase-shaped growth habit
• 'Columnaris'
  • no shearing is needed to maintain its natural "tall hedge" shape
  • columnar growth habit

Liabilities

• legginess with age (for both cultivars, but 'Columnaris' is more obvious)
• abscised juicy fruits will stain any nearby hardscape features or automobiles in late Summer
• nematodes (root-devouring microscopic "worms") and/or yearly Japanese Beetle infestations can lead to a severe decline of the shrub
• poor fall color
• 'Asplenifolia' has very brittle stems and branches (which are not a liability except during handling and transplanting)

Habitat

• zones 2 to 7
• the species form (which resembles a more open and spreading form of 'Columnaris') is native to Europe, Western Asia, and North Africa, but has become naturalized (via seed dispersal) in the Eastern United States

SELECTIONS

Alternates

• upright shrubs used as unpruned visual screens (Juniperus, Thuja, Viburnum x rhytidophylloides, etc.)
• deciduous shrubs with very fine-textured foliage (shrub members of the Willows, including Salix purpurea)
• evergreen companion shrubs with fine-textured foliage (dwarf shrub members of the following genera: Abies, Chamaecyparis, Juniperus, Picea, Pinus, Taxus, Tsuga, etc.)

Variants

• as mentioned throughout the above text:
  • Rhamnus frangula 'Asplenifolia' - Fernleaf Buckthorn or Cutleaf Buckthorn - leaves are linear with a wavy margin, fine-textured and eye-catching, vased in growth habit, and a visual alternative for Willow shrubs (except in permanently moist to wet sites)
  • Rhamnus frangula 'Columnaris' - Tallhedge Buckthorn - foliage is oval (like the species form), but its habit is very columnar and it is often used as a tall visual screen to hide utilities or demarcate property lines, or in formal gardens to partition "outdoor rooms"; having many twisting stems, crossing branches, and girdling trunks, with legginess becoming a liability with age

Translation

• Rhamnus is the Greek name for another shrub.
• frangula is the Latin name for Alder Buckthorn.

Purpose

• Rhamnus frangula has two cultivars that give this species importance in the landscape, in terms of their fine-textured ('Asplenifolia') or columnar ('Columnaris') design functions.

Summary

• Glossy Buckthorn or Alder Buckthorn is known almost exclusively for its two cultivar forms, prized for their ultra fine-textured foliage ('Asplenifolia', or Fernleaf Buckthorn) or usage as a tall hedge that does not need shearing ('Columnaris', or Tallhedge Buckthorn).