Feel free: Ostrya HopHornbeam

Tuesday, March 4, 2014

Ostrya HopHornbeam

The Ostryas are a family of 10 species of trees that are related to the Birch. They are native of woodlands of temperate regions of the Northern Hemisphere. They grow best in fertile, well drained soil in both sun and shade. They are very tolerant of drought once established but not compactiion or salt. Hophornbeams are also rarely bothered by insects or disease.
The fruits on the Hop Hornbeam are bracted seed clusters that look very similar to the Hops used in making beer hence the name.
Seeds should be planted in pots protected from extreme cold and germinate in the spring. Based on my own observations; I rate the Hop Hornbeam a 10 / 10 for ornamental use since I really cant think of anything bad to say about them. They most certainly should be planted more often.

Ostrya carpinifolia ( European Hop Hornbeam )
Native to Turkey and southern Europe; this is usually a medium size tree that is conical in youth becoming rounded with age. The fast growth recorded is 50 x 33 feet in 20 years and the largest trees on record reach 80 x 73 feet with a trunk diameter of over 5 feet.
The double toothed, pointed tipped leaves are up to 6 x 2.5 inches in size, are lush green and color later in fall than Ostrya virginiana turning golden. The flowers and fruit are similar to Ostrya virginiana.
The bark is gray and scaly.
Hardy from zone 3 to 9 and grows very well in both eastern North America, the Pacific Coast and in western Europe.

* photo taken on 4th of July 2010 in Washington, D.C.

Ostrya chisoensis ( Chisos Hop Hornbeam )
Native to elevations of 4500 to 7000 feet in Big Bend National Park in Texas; it is exceptionally drought tolerant and grows smaller to only 40 x 25 feet; though has the potential to reach 47 feet with a trunk diameter of a foot on excellent sites.
The deep green, ovate leaves are curled and hairy, up to 2.5 x 1.3 inches. They are hairy, pale green below with a finely double serrate edge.
The fruit clusters are up to an inch in length.
The branches have a fine, delicate appearance.
The brown bark is also very attractive. It is smooth on young trees later becoming shaggy with thick, long narrow strips.
Very rare and native only to heavily shaded drainages in the Chisos Mountains in southwestern Texas. It should be tested as an ornamental tree in dry climate regions ( likely hardy zones 5 to 8 ).

Ostrya japonica ( Japanese Hop Hornbeam )
Native to northeast Asia, China and Japan; this is the largest of the HopHornbeams and is capable of reaching as much as 110 x 60 feet with a trunk diameter up to 4 feet. The young shoots are soft hairy and the serrate edged leaves are oblong and hardy above. They are dark green above and light green felted below. A vigorous tree; it is hardy from zone 5 to 8 and should be tested in zone 4.
The Japanese Hop Hornbeam grows very well in both eastern North America, the Pacific Coast and in western Europe.

Ostrya knowltonii ( Knowltons Hop Hornbeam )
Also native southwest of the range of Ostrya virginiana, from mountains of Utah and Colorado; south to Arizona to southwestern Texas. and exceptionally drought tolerant as well. It grows to 30 feet tall and wide; though some may reach 40 feet.
The leaves are oval and curled, up to 1.8 inches in length.
They are deep green above and hairy beneath.
The brown flower catkins are short, up to an inch and are appear as the tree leafs out.
The brown fruit cones are up to an inch in length.
The twigs are hairy and slender.
Rare and widely scatterred in the wild and rarely cultivated; though an EXCELLENT ornamental tree for dry climates. Hardy zones 6 to 8.

Ostrya rehderiana ( Rehder Hop Hornbeam )
Also called Tianmu Ironwood. A medium size tree, reaching up to 70 feet tall and wide with a trunk diameter up to 3.5 feet. It is is only distributed in the west of Tianmu Mountain in northwest Zhejiang Province.
Moderately fast growing, on ideal sites it may grow at a rare up to 2 feet per year.
The leaves are up to 6 x 2.5 ( usually 4 x 2 ) inches.
The rough bark is gray.
Only hardy north to zone 6; this tree is endangered with extinction with only 5 trees left in the wild.

* photos taken on Aug 25 2011 @ Scott Arboretum, Swarthmore, PA

Ostrya virginiana ( Eastern Hop Hornbeam )

From central and eastern Canada & the U.S.; this tree is typically conical in youth becoming rounded at maturity. Seedlings grow moderately fast - even in shade reaching up to 7 feet in 5 years on average. Typically maturing around 40 feet; on ideal sites it can grow much larger and the largest trees on record approach 90 feet tall; 110 feet wide with a trunk diameter of 4 feet. The Eastern Hop Hornbeam is very long lived up to 300 years though after 100 years of age they become very slow growing so that these trees never compare in size to similarly aged Oak. The shade cast by the dense canopy is very deep.
The leaves are ovate and serrated up to 5 inches ( though Ive measured 8 x 4 inches on vigorous shoots on trees in the Canard River Valley near Amherstburg, Ontario ).
They are dark green above and paler below; turning brilliant clear yellow in autumn.
The early spring flowers appearing with the folaige in spring are yellow catkins followed by fruit clusters up to 2 inches long that ripen to light brown in the fall.
The twigs are very slender like that of the Birch.
The brown bark is also very attractive. It is smooth on young trees later becoming shaggy with thick, long narrow strips.
The wood is hard and very heavy ( 50 pounds per square foot ).
Extremely cold hardy thriving from zone 2 to 9; this tree reaches up to 33 x 34 feet in North Dakota and even grows far outside its native range in Saskatoon on the Canadian Prairies. Rare in cultivation; it should be planted much more.
While it is a very attractive tree; the Hop Hornbeam is rarely seen along highways as road salt kills it. It is also very sensitive to sulfer / nitrogen oxide, chlorine and flourine. Despite all this; most trees I observed in both Maryland and Ontario either in forests or landscaping that were located away from road salt spray / runoff or salted walkways appear extremely healthy and resistant to insects, disease, ice damage and deer. An excellent tree for small back yards, patios, golf courses and parks.
An elegant tree that looks good in all seasons.

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