Sunday, May 16, 2010

Kalopanax pictus - Castor Aralia

The lone member of the Kalopanax family but a member of the much larger or more like huge Araliaceae tribe. It is a moderate to fast growing, broadly columnar to rounded, large tree that is native to cool forests of northeast Asia ( China & eastern Russia, Korea & Japan ) and can reach 70 feet or more. Some records include: fastest growth rate - 5 feet; 7 years - 20 feet; 20 years - 60 x 60 feet; 31 years - trunk diameter of 27 inches; largest trees ever recorded - 133 x 90 feet with trunk diameter up to 8 feet in old growth forests in its native lands. It can eventually grow large elsewhere and one in the U.S. already measures 60 x 50 with a trunk diameter of 3 feet in New Haven, Connecticut. Another very large tree ( 65 x 93 x 4.4 feet ) grows at Westtown School, Westtown, PA. Long-lived, the Castor Aralia is known to persist as long as 360 years. The Castor Aralia has a very dense canopy, strong branches and is a long lived tree. The Castor Aralia is rarely seen in North America but should be much more widely used.
The palmately lobed leaves have 5 or 7 toothed, taper pointed lobes, The leaves can be up to 8 inches long and wide though are known to occasionally reach up to 15 x 17 inches in very vigorous shoots. The leafstalks are up to 10 inches or very rarely double that in length. The Castor Aralia is coarse-textured and provides a tropical effect. The leaves are reddish at first during spring when they are also downy beneath, they emerge early in the spring. In summer they turn to glossy deep green above and often turn to deep yellow or red during autumn.
The flowers are tiny and white, however are borne abundantly on large rounded clusters up to 2 feet across in late summer.
They are followed by bluish black rounded berries up to 0.25 inches across.
The stems are stout and sometimes spiny. The deeply-fissured bark is blackish brown.
Hardy zones 4 to 7 and has been known to tolerate -37 F with no damage. It prefers full sun or partial shaade on deep, fertile, moist, well drained loam soil whether acidic or alkaline. It is a very low maintenance tree and is not generally attacked by insects or disease. It can be propagated from seed as well as root cuttings or softwood cuttings ( difficult ) taken in summer. To enhance germination; the seed should be soaked in sulfuric acid for 30 minutes, then washed under cold water for 10 minutes.

* historical archive photos

* photos taken on May 16 2010 @ Cylburn Arboretum, Baltimore, MD

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

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

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

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