Tuesday, August 17, 2010

Buckthorn

Rhamnus

A genus of 125 species of trees and shrub that are part of the larger family called Rhamnaceae that includes many more plants. Rhamnus are widespread in the Northern Hemisphere and are also native to South Africa, eastern Africa and Brazil.
Most prefer full sun to partial shade on any reasonably fertile soil.
Buckthorns to not like root disturbance and should be transplanted while very small.
Propagation is from sowing ripened seed in autumn, or layering.
Deciduous species can also be reproduced from softwood cuttings taken during early summer. Evergreen species can be reproduced from half hardened cuttings taken during summer.

Rhamnus alaternus ( Italian Buckthorn )
A fast growing, thornless, upright, open, evergreen shrub to small tree, native to the Mediterranean and Black Sea regions. Some records include: 2 years - 8 feet; 20 years - 20 x 17 feet; largest on record - 47 x 27 feet with a trunk diameter of 1.3 feet.
Tolerant of shearing, it makes an excellent tall hedge or screen.
The finely-toothed leaves, are up to 4 x 2 inches in size.
The leathery foliage is glossy deep green.
The small yellowish-green flowers borne in axilliary clusters, during late spring
They are followed by berries during late summer, that are green, ripening to red then black.
The stems are reddish-brown.
Hardy zones 7 to 10 in sun or partial shade on very well drained soil. Italian Buckthorn likes calcium in the soil and hates soils that are poorly drained where root rot may occur. The Italian Buckthorn thrives especially well on the west coast in the U.S. This very tough plant is very tolerant of drought, salt air and pollution.

* photos taken by Jean Pawek @ CalPhotos

* excellent video found on internet


'John Edwards'
Very fast growing, longer lived and dieback resistant. The foliage is glossy bright green.

'Variegata'
Also called 'Argenteo-Variegata'. The very attractive, oval leathery foliage has a gray-green center with a wide white margin.
It is fast growing and bushy.

Rhamnus alnifolia ( Alderleaf Buckthorn )
A small deciduous shrub, reaching up to 6.5 ( rarely over 4 ) feet, that is native to wet woods, swamps and bogs in northern North America ( from near Nelson, British Columbia to Fort McMurray, Alberta to Saskatchewan to York Factory, Manitoba to far northern Ontario to central Quebec to Newfoundland; south to northern California to southern Idaho to western Wyoming to North Dakota to northern Illinois to northern Ohio to northern Pennsylvania...south to Tennessee in the Appalachian Mountains ). In the Windsor/Essex County, Ontario region; it was locally common in swampland along Lake St Clair during the 1800s. Some very old colonies have been known to spread up to 50 feet across though it is not normally considered invasive.
The alternately-arranged, finely-toothed, elliptical leaves are up to 4.5 x 2.3 inches in size. The foliage is glossy mid to deep green. The leaves are often crowded towards the stem tips.
The greenish-yellow flowers, up to 0.2 inches wide, are borne in axillary clusters of 2 to 3.
The black berries are up to 0.25 inches wide.
Hardy zones 2 to 6 in partial to full shade on permanently moist to wet soil. It is fully hardy on the northern Great Plains.

* photo taken by Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database


Rhamnus alpinus ( Alpine Buckthorn )
A deciduous shrub, reaching a maximum height of 13 feet, that is native from Spain to Greece.
The finely-toothed leaves, are up to 4 x 2 inches.
The tiny bright green flowers, borne during late spring, are followed by red drupes.
The stems do NOT have thorns.
Hardy zones 5 to 9 ( possibly 4b as it thrives at Dominion Arboretum in Ottawa, Canada )

Rhamnus betulifolia ( Birchleaf Buckthorn )
A rounded, deciduous large shrub to small tree, native to moist canyons in the western U.S from southern Nevada to southwest Colorado, Arizona, New Mexico and western Texas; south into central Mexico. It is very similar to Rhamnus caroliniana. Some records include: largest on record - 25 x 45 feet with a trunk diameter of 1 foot.
The elliptic leaves, are up to 6 x 1.6 inches in size. The foliage is glossy bright green, turning to bright yellow during autumn.
The greenish-yellow flowers borne in clusters, during early summer
They are followed by black berries.
Hardy zones 6 to 9 ( est ) in full sun on well drained soil. It is very heat tolerant and also tolerant of alkaline soil.

Rhamnus californica ( Coffeeberry )
An attractive moderate growing, upright evergreen shrub native to southern Oregon, California, southern Nevada, central & southern Arizona and New Mexico. Some records include: largest on record - 30 x 40 feet with a trunk diameter of 1 foot. Coffeeberry makes a great tall hedge or screen.
The finely toothed, elliptical to oval leaves, are up to 5 x 2 inches in size.
The foliage is reddish at first, turning to glossy rich green.
The bright greenish-yellow unisex flowers borne late spring into early summer. The flowers attract hummingbirds and butterflies.
They are followed by round berries that are deep red ripening to black.
Hardy zones 7 to 10 ( tolerating as low as 0 F ) preferring partial shade on light, well drained soil.

* photos taken by Jean Pawek @ CalPhotos

* historic archive photo


'Bonita Linda'
Upright and dense in habit, reaching up to 8 x 10 feet in size, it makes a great screen.
The intensely gray foliage contrasts nicely with the red ( later turning black ) berries.

'Ed Holm'
Attractive shrub reaching maximum size of 6 x 15 feet. Glossy mid green foliage.

'Eve Case'
An attractive, moderate growing, dense, compact shrub reaching maximum size of 8 x 7 feet bearing tasty fruit.
The large, broad foliage is glossy deep green.
The berries are large.
Hardy to as low as -7 F

'Mound San Bruno'
Attractive moderate growing, dense, mounding shrub reaching maximum size of 6 x 15 feet.
The narrow foliage is very dark green.
Hardy zones 7+.

Rhamnus caroliniana ( Carolina Buckthorn )
A strong branched, upright-oval, medium-size tardily deciduous tree native to eastern North America ( from central Missouri to northeast Indiana to southwest Virginia; south to central Texas to central Florida ). It is not common in the cultivation or in the wild where it is found in moist deciduous forests and river bottomlands. Some records include: fastest recorded growth rate - 3 feet; largest on record - 50 x 20 feet with a trunk diameter of 1.3 feet. Carolina Buckthorn is ideal for screening.
The almost smooth edged, taper pointed, elliptical leaves, are up to 7 x 2 inches in size. The strongly veined, handsome foliage is glossy deep green, turning striking golden-yellow and orange during autumn.
The greenish-white flowers borne in clusters, during mid spring.
They are followed by persistant, attractive, glossy red, later turning to black fruits, up to 0.4 inches. The flesh is dryer than that of Rhamnus purschiana. This is among the very few Rhamnus species with edible berries.
The slender gray twigs have pale lenticels and yellow-brown buds.
The smooth bark is ashy gray. Very old trees may have slightly furrowed bark.
Hardy zones 5 to 9 in sun or shade on moist fertile soil and is both heat and drought tolerant. It transplants poorly and is best grown from seed.

* photo taken on Oct 21 2014 @ U.S. Botanical Gardens, Washington, DC

* photo taken by W.D. Brush @ USDA-NRCS PLANTS Database

* historical archive photos


Rhamnus cathartica ( Common Buckthorn )
A thorny deciduous large shrub to small tree native to temperate regions of Eurasia as well as northern Africa. Some records include: fastest recorded growth rate - 4 feet; 10 years - ; largest on record - 61 x 65 feet with a trunk diameter of 5.8 ( 2.7 for single trunk ) feet. It may form dense thickets and in parts of North America is considered invasive. It has naturalized in eastern North America to as far north as International Falls, Minnesota and Wiarton, Ontario.
The finely-toothed, oval to rounded leaves, are up to 3 x 2.5 inches in size. The foliage is glossy mid-green above, furry light green beneath; turning yellow during late autumn to early winter. The leaves appear very early during spring.
The small unisex flowers are borne in axilliary clusters, during late spring.
They are followed during autumn with fleshy, rounded berries, up to 0.5 inches wide, that are red, ripening to black and persisting into winter.
The bark on young stems is dark with white lenticels, on older stems dark gray, rough, scaly and ridged. Some trees may have scaly orange-brown bark.
Hardy zones 2 to 7, it is tolerant of both flooding and drought as well as alkaline soil. It is fully hardy on the northern Great Plains.

* photo taken on August 3 2010 @ Univ. of Guelph Arboretum, Ontario

* photo taken on August 5 2010 in Clinton, Ontario


* photos taken on Aug 4 2013 in Bayfield, Ontario

* photos taken on July 27 2015 in Bayfield, ON

* historical archive photos

* video found on Youtube


Rhamnus crenata ( Crenate-Leaved Buckthorn )
An upright, deciduous shrub or small tree, reaching up to 23 ( rarely over 13 ) feet, that is native to much of eastern China as well as Korea, Japan and northern Burma, Thailand and Vietnam. It makes a great hedge.
The obovate leaves are up to 5.5 x 2 inches in size. The attractive, deeply-veined, large foliage is glossy mid-green.
The tiny flowers appear during early summer.
They are followed by red ( later ripening to black ) berries, up to 0.3 inches wide, ripening during late summer and persisting into mid-autumn.
The roots contain a yellow dye and also an insecticide.
Hardy zones 3b to 9, it thrives at Dominion Arboretum in Ottawa, Canada but is generally unknown in North America.

Rhamnus crocea ( Redberry )
A moderate growing, spreading evergreen large shrub to small tree that is native to all California, the Baja Peninsula, New Mexico and northwest Mexico. Some records include: fastest recorded growth rate - 2 feet; largest on record - 30 x 45 feet with a trunk diameter of 1.5 feet.
The slightly tooth-edge, elliptic leaves, are up to 2.5 inches in length. The foliage is glossy green.
The flowers are borne in small clusters.
They are followed by red fruit. This is among the very few species with edible berries.
The twigs are often thorny.
Hardy zones 7 to 10 tolerating as low as 0 F, requiring average rainfall between 22 & 50 inches.

* photos taken by Jean Pawek @ CalPhotos

* photo taken by Albert Everett Wieslander and the Marian Koshland Bioscience and Natural Resources Library

* excellent video found on internet


Rhamnus davurica ( Dahurian Buckthorn )
A fast growing, small deciduous tree native to eastern Siberia, Kamchatka, Mongolia, Manchuria and Korea. Some records include: largest on record - 35 feet with a trunk diameter of 1 foot.
The toothed, broadly-elliptical leaves, are up to 6 x 2.3 inches in size. The leathery foliage is glossy deep green.
The greenish-cream flowers borne during late spring.
They are followed by berries, up to 0.25 inches wide, that are red, later turning to black.
The stout twigs are spiny.
Hardy zones 2 to 7, it is fully hardy on the northern Great Plains.

Rhamnus fallax ( Carniolian Buckthorn )
An evergreen shrub reaching a maximum height of 10 feet, that is native from southern Europe to the Middle East.
The toothed, oblong leaves, are up to 6 x 3.7 inches in size.
The foliage is gray-green.
The flowers are borne during late summer.
Hardy zones 6 to 10

Rhamnus frangula ( Alder Buckthorn )
Also called Frangula alnus. A broadly-spreading, deciduous, small tree to around 20 feet, that is native from the British Isles into western Russia, as well as northern Africa. It has escaped into the wild in the northeast U.S. and southern Canada ( to as far north as Tobermory, Ontario ) and is invasive in some areas, especially moist woodlands. Some records include: fastest recorded growth rate - 3 feet; 20 years - 27 x 17 feet; largest on record - 40 x 30 feet with a trunk diameter of 3 feet.
The smooth-edged, oval to obovate leaves, are up to 4 x 2 inches in size. The foliage is glossy deep green above, hairy light green beneath; turning to red ( sometimes yellow ) during autumn.
The small, greenish, unisex flowers borne in axilliary clusters, during late spring. The flowers attract Honey Bees.
They are followed by fleshy berries, up to 0.5 inches, that are red ripening to black.
The gray bark is smooth with shallow, pale, vertical cracks.
Hardy zones 2 to 7 tolerating as low as -50 F in sun or shade. It is fully hardy on the northern Great Plains. Young trees should be pruned to a single leader and feathered ( shortening and spacing branches ). Alder Buckthorn can be thinned and cut back hard during early spring. Deer resistant.

* photos taken on Oct 21 2014 in Washington, DC

* photos taken on July 27 2015 in Bayfield, ON


'Asplenifolia'
Reaching up to 15 x 12 feet, sometimes more, with fine textured, threadlike foliage.

'Columnaris'
Vigorous, tall and narrow; it is great for hedging. Some records include: 10 years - 13 x 4 feet; largest on record - 23 x 6.5 feet.

'Fineline'
A moderate growing, narrow, upright, columnar shrub, reaching up to 15 x 5 ( rarely over 11 x 4 ) feet, that combines the upright habit of 'Columnaris' with the feathery foliage of 'Asplenifolia'. It makes an excellent architectural plants, great for framing enterences and even for patio planters. It also makes a great narrow screen for townhouses and urban lots.
The finely dissected foliage is deep green, turning to brilliant orange-yellow during autumn.
It produces very few fruits and is not invasive.
Hardy zones 2 to 7, tolerating as low as -50 F.

* photos taken on July 4 2014 in Ellicott City, MD

* photo taken on Aug 26 2016 in Columbia, MD

* photo taken on Apr 23 2017 @ Brookside Gardens, Wheaton, MD

* photo taken on May 28 2017 in Ellicott City, MD

* photos taken on Aug 5 2017 @ Brookside Gardens, Wheaton, MD


'Latifolia'
Very rare, native to the Azores. It is less cold hardy ( zone 7 est. ) but has much larger leaves, up to 5 x 3 inches.

Rhamnus glandulosa ( Canary Buckthorn )
A small tree, reaching a maximum height of 33 feet, that is native to the Canary and Madiera Islands in the Atlantic Ocean. It is endangered with extinction in the wild.
The leathery leaves, up to 3 inches in length, are glossy deep green.
The yellowish-green flowers borne in clusters are followed by purplish-black berries.
The bark is gray.
Hardy zones 10 to 11 ( est ) requiring a mediterranean climate.

Rhamnus imeretina
A very attractive, spreading, deciduous shrub, reaching a maximum size of 12 x 15 feet, that is native to the Black Sea region.
The oblong leaves, are up to 14 x 6 inches in size.
The strongly veined foliage is dull green above, felted light green beneath, turning to bronze-purple in autumn.
The greenish unisex flowers borne in axilliary clusters, during summer.
They are followed by fruit that ripens to black.
Hardy zones 5 to 9. Shade tolerant.

Rhamnus infectoria ( Avignon Berry )
A dense, deciduous handsome shrub reaching a maximum size of 15 x 15 feet, that is native from southern Europe to Iran.
The oval leaves are up to 1.5 x 0.7 inches in size. The glossy, bright green foliage turns to yellow during autumn.
The small, yellow flowers appear with the emerging foliage during mid-spring.
They are followed by fruits, up to 0.2 inches long.
Hardy zones 3b to 7, it has proven to be hardy in trials at Indian Head, Saskatchewan.

Rhamnus japonica ( Japanese Buckthorn )
A deciduous large shrub, reaching up to 20 ( rarely over 10 ) feet in height, that is native to most of Japan.
The oblong leaves, up to 3.2 x 1.6 inches in size, are glossy deep green above, bright green below.
The yellow flowers, up to 0.2 inches wide, appear during late spring.
They are followed by showy, black berries, up to 0.3 inches wide, that persist into winter.
Hardy zones 4 to 8, it thrives in the Ottawa Valley of Canada but is generally unknown in North America.

Rhamnus leptophylla ( Narrow Leaved Buckthorn )
A small tree native to much of China. Some records include: largest on record - 34 x 32 feet with a trunk diameter of 1.6 feet.
The obovate leaves, up to 3 x 2 inches in size, are papery deep green above, pale green beneath. The abundant berries are black.
The stems are glossy yellowish-brown. The bark on older trees is gray.
Hardy zones 5 to 8.

Rhamnus maximowicziana
A dense, deciduous, medium-sized shrub, reaching up to 8 feet in height, that is native from south-central Mongolia into central China.
The broadly-ovate to elliptical leaves are up to 5 x 1.5 inches in size. The foliage is mid-green above, bright green beneath.
The tiny flowers are borne during late spring.
They are followed by berries, up to 0.2 inches wide, that are red later turning to black.
Hardy zones 4 to 7.

Rhamnus prionoides ( South African Dogwood )
A handsome, very dense, spineless, medium size, evergreen tree native to mountains of tropical Africa and those of eastern South Africa. The roots are not aggressive to it can be used in confined areas.
Some records include: 10 years - ; largest on record - 33 x 15 feet.
The leaves, are up to 4 x 2 inches in size.
The strongly veined, leathery foliage is very glossy deep green above, light olive green beneath.
The small creamy flowers borne in the leaf axils clusters, spring into early summer.
They are followed by small red berries that ripen to black.
Hardy zones 9 to 11.

Rhamnus pumila
A beautiful groundhugging deciduous shrub native to mountains of central and southern Europe. It has excellent potential as groundcover, especially on commercial sites. Some records include: largest on record - 5 feet
The finely toothed, elliptic to rounded leaves, are up to 2.7 inches in length. The foliage is glossy deep green.
The fruits, up to 0.3 inches, are black.
Hardy zones 5 to 8 in full sun on well drained soil.

Rhamnus purshiana ( Cascara )
An open, medium-size, deciduous tree that is native to western North America ( from the Queen Charlotte Islands to Revelstoke, British Columbia to far southwest Alberta; south to northern California to central Idaho & western Montana ). Some records include: fastest recorded growth rate - 2 feet; largest on record - 70 x 60 feet with a trunk diameter of 3 feet; longest lived - 60+ years. Trees will often resprout from the stump if cut near the ground. It is most often found on riverbanks in the wild.
The finely toothed, broadly-elliptical leaves, are up to 8 x 3 inches in size. The foliage is very glossy green, turning to yellow during late autumn.
The tiny yellow-green flowers borne in small axilliary clusters, during late spring.
They are followed by black fruits, up to 0.6 inches.
The smooth bark is gray-brown, with creamy colored stripes. The wood is heavy, weighing around 37 pounds per square foot.
Hardy zones 3 to 8 requiring 40+ inches of yearly average precipitation. It grows in sun or shade and prefers moist soil. Thrives in the British Isles. Though nearly unknown in eastern North America; it has survived over 60 years at Dominion Arboretum in Ottawa, Ontario where it has suffered winter dieback but resprouts vigorously. Propagation is from semi-ripe cuttings or seed.

* photo taken by http://www.nwplants.com

* excellent video found on Youtube


Rhamnus saxatilis ( Rock Buckthorn )
A very twiggy, thorny, deciduous shrub, reaching a maximum size of 8 x 8 feet, that is native to central and southern Europe. While there is no data on record size, it has already reached 8 feet across at Dominion Arboretum in Ottawa, Canada and larger sizes are possible.
The finely-toothed, ovate to rounded leaves, are up to 2 inches in length.The foliage is medium-green.
The flowers are creamy-white.
They are followed by drupes that are red turning to black.
The side shoots are often tipped in spines.
Hardy zones 3 to 8.

Rhamnus utilis ( Chinese Buckthorn )
A deciduous large shrub to small tree, reaching a maximum size of 27 x 27 feet, that is native to much of central & eastern China and also Korea and Japan.
The tooth-edged, ovate leaves, are up to 6 x 3 inches in size. The foliage is glossy deep green above, bright yellow-green beneath.
The flowers are yellowish-green, and are followed by a black berry.
Hardy zones 4b to 9, it thrives at Dominion Arboretum in Ottawa, Canada but is mostly uknown in North America.

* photos taken on Jul 18 2017 @ Dominion Arboretum, Ottawa, ON

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