Friday, March 12, 2010

Wheel Tree

Trochodendron aralioides
The "Wheel Tree" from Korea, central & southern Japan and Taiwan is endangered in the wild. It is one of the worlds most primative currently existing plants. An interesting and attractive evergreen tree; it has chocolate brown bark and oval leaves, up to 6 x 3 inches, that are bronze-red at first, turning lush glossy green for remainder of season. The leathery leaves are whorled towards the tips of the branches which are tiered.
The bright yellowish-green flowers appear on showy inflorescences during late spring.
For an evergreen broadleaf tree it is very hardy to both heat and cold and can tolerate flooding. Considered hardy to zone 6 it has been reported to grow in Wilkes-Barre, PA & one has reached 21 x 30 x 1 feet in New Jersey, It can reach up to 5 feet in 3 years from seed, 27 feet in 16 years, and be moderate growing ( 3.3 feet per year being the probable record rate ). Mature size in southeast U.S. is unknown, I would predict around 40 feet though heights of 100 feet and trunk diameters of 7 feet exist in the wild in Asia.
It prefers to be planted on acidic, fertile, moist soils in partial shade and protected from wind.
Propagation can be from semi-ripe cuttings taken during summer, but trees propagated from seed sown in autumn tend to be faster growing.

* Photos taken Feb 2009 @ U.S. National Arboretum, Wash., DC
* photo taken on May 8 2010 @ U.S. National Arboretum, D.C.

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

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

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

* photos taken on Mar 18 2017 @ Brookside Gardens, Wheaton, MD

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


Tetracentron sinense
A sole member of the Tetracentron genus which is part of the small Trochodendron genus. It is a fast growing, long lived ( up to 280 years ), dome to Elm-shaped deciduous tree reaching around 80 feet, that is native to mountains of the eastern Himalayas and southern China. Some records include: largest on record - 133 x 50 feet with a trunk diameter of 6.4 feet. Fossils indicated that its range has been seriously restricted due to previous Ice Ages and that it once occured in Washington State, British Columbia, Iceland and Europe. It is a very attractive world class shade tree.
The pointed, ovate leaves are similar to that of Hackberry - Celtis occidentalis but are wide and heart-shaped.
The leaves, up to 7 x 5 inches, are bronze green at first, turning deep green in summer, turning deep red in autumn.
The tiny yellowish-green flowers are borne in catkins up to 6 inches in length.
The smooth flaking bark is pale red-brown, light gray and white. The very beautiful exfoliating bark somewhat resembles that of the Lacebark Pine.
Hardy zones 5 to 7 thriving in sun or shade on deep, neutral to acidic soil.
It will tolerate alkaline soil but with less vigor.
Extremely easy to grow ( anywhere you can grow Rhododendrons and Azaleas ); it is not bothered by pests or diseases.

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