Wednesday, June 23, 2010

Zelkova

Zelkova

With 5 species of tree native from the Caucasus to Japan but planted around the world, the Zelkovas are very valuable shade and street trees that are related to the Elms but are never bothered by diseases of the Elms. Young trees should be pruned to encourage a strong single trunk and protected from strong winds in order to develop a well shaped tree. They are clay tolerant as well as very PH tolerant. They prefer full sun to partial shade on deep, fertile, well drained soil. Propagation is from seed for the species. For the garden cultivars; either from grafting or root cuttings from young potted trees. The Zelkovas can tolerate drought but still require 20 inches or more of rainfall per year.

Zelkova abeliacae ( Cretan Zelkova )
Native to the Greek Island of Crete and is endangered with extinction though it has been planted outside of Greece in places such as England where it suprisingly thrives in much cooler summers than found in its native range.
Some records include: 20 years - 27 feet; largest on record - 50 feet tall with a trunk diameter of 16 inches though reported to have reached up to 120 x 82 feet centuries ago when the Greek Islands were much more forested.
The heavily serrated leaves are up to 2 inches in length.
The small scented flowers are pollinated by insects. Seed is not abundant but can be sown during autumn.
Cuttings of young shoots also root with a good success rate when taken in late mid to late summer and root cuttings have about a 50% success rate. Unlike the others; this Zelkova commonly suckers.
Hardy zones 5 to 9

Zelkova carpinifolia ( Caucasian Zelkova )
A fast growing Elm-like tree native from Turkey to northern Iran though commonly planted in England and western Europe. A very large, upright, round-headed tree that can reach 100 feet or more but rarely reaches that height due to its tendancy to grow with many competing leaders unless trained when young. Some records include: fastest recorded growth rate - 5 feet; 9 years - 37 feet; 20 years - 66 feet; 250 years - trunk diameter of 7.5 feet; largest on record - 200 x 80 feet with a trunk diameter of 20 feet. The largest in Pennsylvania exceeds 5 feet in trunk diameter and grows at Woodlands Cemetary in Philadelphia. The Caucasian Zelkova is very long lived and is also among Europe's largest hardwood trees.
The coarsely-toothed, oval leaves are up to 6 x 3.5 inches on vigorous shoots but usually half that. They are smooth, glossy, deep green above and downy below. Its foliage can be told apart from other Zelkovas by its 10 pairs veins ending at the ends of triangular teeth. The foliage turns to orange-red in November.
The bark is gray-white and smooth; flaking with age. The young stems are very downy.
The flowers are pleasantly scented but barely visible.
Hardy zones 4 to 9 and very heat tolerant. Very rare in the U.S.; it is known to grow at the Mall in DC near the reflecting pool.

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




* photos taken on Sep 3 2017 @ U.S. National Arboretum, D.C.

* historic archive photos


Zelkova schneideriana ( Schneider Zelkova )
A large tree that is very similar to Zelkova sinica but is native to southwestern China instead of eastern China. It is slower growing and smaller than the other Zelkovas. Some records include: fastest recorded growth rate - 2 feet; 26 years - trunk diameter of 20 inches; largest on record - 120 feet tall with a trunk diameter of 3 feet.
The finely-toothed leaves, up to 5.5 x 2 inches in size, are deep green above and downy below. The leaves are very deeply-cut, far more than the other Zelkovas. The foliage turns to outstanding scarlet in the fall.
The gray bark is flaking and scaly.
Hardy zones 5 to 9, thrives as far south as Savannah, Georgia.

* photos taken on 4th of July 2010 @ U.S. National Arboretum, D.C.



* photos taken on July 17 2010 @ Morris Arboretum, Philly, PA


* photos taken on June 23 2013 @ U.S. National Arboretum, DC

* photo taken on Feb 8 2014 @ U.S. National Arboretum, DC

* photos taken on Apr 24 2016 @ U.S. National Arboretum, DC

* photos taken on Sep 3 2017 @ U.S. National Arboretum, D.C.


Zelkova serrata ( Japanese Zelkova )
One of the worlds largest hardwoods, can reach well over 100 feet, live to 1500 ( very rarely over 1000 ) years old and is native to eastern China and Japan. It generally grows with a thick, stocky trunk and a broad spreading crown. Some records include: fastest recorded growth rate - 8 feet with a trunk diameter increase of 1 inch; 7 years - 25 x 25 feet; 14 years - 40 feet; 40 years - 90 x 80 feet with a trunk diameter of 5 feet ( Columbia, Maryland ); largest on record - 200 x 100 feet with a trunk diameter of 17 feet; largest in PA - 92 x 90 feet with a trunk diameter of 7.4 feet @ Delaware Community College, Media, PA. Largest in U.S. is at the legandary tree lovers Spring Grove Cemetary in Cincinnati, Ohio
The heavily-toothed and veined, ovate leaves reach a maximum size of 6 x 2.5 inches in vigorous shoots though usually much less. The are rough & deep green above, paler and finely hairy to smooth below. The foliage turns to gold, orange and wine red late in the fall.
The small green flowers are borne in early spring before the leaves.
The curved very slender twigs are brown with small buds.
The bark is usually light gray flaking to reveal orange beneath.
The timber is of high quality.
Hardiness is generally zones 5 to 9 but varies to as much as to zone 3 depending on seed source. It is both tolerant of wind, floods and soil PH from 3.7 to 7 though it does not like sandy soil.

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






* photos taken on July 17 2010 @ Morris Arboretum, Philly, PA





* photo taken on Nov 8 2011 in Columbia, MD


* photos taken on Feb 20 2012 in Columbia, MD





* photos taken on May 17 2012 in Columbia, MD

* photo taken on July 1 2015 in Columbia, MD

* photos taken on Aug 14 2015 in Columbia, MD

* photo taken on July 12 2016 in Columbia, MD

* photos taken on June 20 2017 in Columbia, MD

* photos taken on Aug 21 2017 in Columbia, MD


'Goshiki'
A slower growing, vase-shaped tree with a wide, flat crown. It can reach 15 x 15 feet in size in 10 years, eventually up to 50 x 45 feet.
The variegated foliage is deep green with creamy white margins. The leaves turn to vibrant red-orange in autumn with some pink edging.
Hardy zones 5 to 8.

* photos taken on May 6 2010 @ Brookside Gardens, Wheaton, MD


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

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

* photo taken on Sep 3 2017 @ U.S. National Arboretum, D.C.


'Green Vase'
A very fast growing vase shaped tree. Brilliant verdant green foliage and excellent fall color. Otherwise similar to 'Halka'

* photos taken on November 2009 in Columbia, MD




* photo taken on March 17 2010 in Columbia, MD

* photo taken on April 6 2010 in Clarksville, MD

* photo taken on April 21 2010 in Columbia, MD



'Halka'
Very fast growing with a strong leader and a broad vase shaped crown resembling that of the American Elm. Some growth records include; 20 years - 66 x 27 feet; 30 years - 80 x 50 feet. Fall color is nothing all that great.

'Village Green'
Fast growing. Rich green foliage.

Zelkova sicula ( Sicilian Zelkova )
Native to Sicily and closely related to Zelkova abeliacae. It is EXTREMELY ENDANGERED in the wild and close to extinction. The few surviving trees are being heavily grazed by goats. While not currently cultivated; that may be the only method to saving this tree which may have loads of potential in dry summer climates where other Zelkovas will not grow. Discovered in 1991, only a few plants remain on the planet.

Zelkova sinica ( Chinese Zelkova )
An extremely vigorous, large, broad canopied tree to 80 feet or more, native to western and north-central China. Some records include: fastest recorded growth rate - 9 feet; 20 years - 50 feet; largest on record - 135 x 100 feet with a trunk diameter of 16 feet. This can develop into one of the worlds most massive hardwoods.
The stort stemmed, pointed, elliptical leaves are up to 5.5 x 2 inches in size though typically 3.5 x 1 inch. The foliage is pinkish at first turning green above, pale and downy beneath. The leaves turn to orange during autumn.
The gray-brown bark flakes off to reveal orange patches beneath.
Hardy zones 3 to 9; it is drought tolerant and also very tolerant of heavy clay.
Though rare in North America, it has been reported to grow well in Illinois, Massachussetts, Washington DC ( Tidal Basin ) and Georgia and everywhere between. Proper pruning and training is reqired when young to develop a well shaped tree since it often can develop multiple trunks.

* photo taken on Feb 8 2014 @ U.S. National Arboretum, DC

* photos taken on Apr 17 2016 @ U.S. National Arboretum, DC


Zelkova × verschaffeltii ( Cutleaf Zelkova )

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

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

3 comments:

  1. I love the pictures you have of the Zelkova tree. Can you please tell me which pictures are "Green Vase" and which are "Village Green"? Thanks...

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  2. Thank you! I just made some edits to the article including new Zelkova sinica photos. Most of the larger Zelkova serrata in my photos predate Green Vase and Village Green being available in the nursery trade and are likely the straight species which is more variable in habit however often can be identical to the form 'Green Vase' in habit. I did just move some photos from Zelkova serrata to 'Green Vase'. Even though they were not labelled where they are growing...the most consistent nearly identical vase-shaped habit makes it likely that is what they are. I still do not have any photos to post of any Zelkovas that are confirmed or likely to be 'Village Green'. Locally 'Green Vase' dominates the nursery trade.

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  3. Do you know much about Zelkova serrata's susceptibility to limb breakage and how to prevent it? This webpage: http://hort.ifas.ufl.edu/database/documents/pdf/tree_fact_sheets/zelserc.pdf
    mentions pruning purchasing trees whose limbs attach separately from each other along the main trunk in order to promote strength. I'm just wondering if you know more.

    ReplyDelete