Rhamnus frangula is known almost exclusively for its 2 cultivar forms, prized for their ultra fine-textured foliage, 'Asplenifolia', Fernleaf Buckthorn, or usage as a tall hedge that does not need shearing, 'Columnaris', Tallhedge Buckthorn.
Alternate common name: Alder Buckthorn
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F E A T U R E S |
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Form
-large foliage shrub for the species form (Glossy Buckthorn) and both cultivars below:
-'Asplenifolia' - Fernleaf Buckthorn (image to the left) matures at about 12' tall x 10' wide; upright vased growth, becoming upright rounded with age
-'Columnaris' - Tallhedge Buckthorn (image to the right) matures at about 12' tall x 3' wide; upright columnar growth habit, upright oval with age
-medium growth rate in youth for all forms, becoming slow with maturity |
Foliage
-'Asplenifolia' (image to the right) has alternate, medium to dark green, deciduous, narrowleaf foliage (about 4" long x 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' (image lower right) has alternate, glossy dark green, obovate to oval, deciduous foliage (about 3" long x 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 |
Fruit
-pendulous berries hang from the leaf axils and undergo a color transition from green to red to black in late summer, maturing in Sept. and devoured by the birds
-the juicy black berries will stain sidewalks or automobiles nearby as they naturally abscise or are dropped during feeding by the birds |
Twig
-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' |
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Trunk
-multi-trunked, 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 |
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C U L T
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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 B&B forms |
Hardiness
-zones 2 to 7
Origin
-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 U.S.
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U S A G E |
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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
-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 autumn color |
Function
-'Asplenifolia'- as a specimen or in group plantings
-'Columnaris'- in row plantings as an informal hedge
Texture
-'Asplenifolia' has ultra-fine texture and average density in foliage and when bare
-'Columnaris' has medium texture and thick density in foliage and when bare |
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S E L
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Varieties
and Cultivars
- Search
OSU PlantFacts for additional plants in this species
Alternates
-upright shrubs used as unpruned visual screens (Juniperus, Thuja, Viburnum x rhytidophylloides)
-deciduous shrubs with very fine-textured foliage (shrub 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) |