Sunday, October 17, 2010

Picrasma

A genus of 8 species of deciduous trees native to China, southeast Asia, the Caribbean and tropical America.
They are excellent street trees and prefer full sun to partial shade on well drained soil on a site protected from excessive winter winds.
Propagation is from seed.

COLD HARDY PICRASMA

Picrasma quassoides ( Korean Quassibark )
A rare, erect, whorled, pyramidal to wide-crowned, medium size, deciduous tree reaching around 50 feet that is native from northeast Pakistan to northern China, Korea and Japan. Some records include: 25 years - 33 x 30 feet with a trunk diameter of 25 years ( New Jersey ); largest on record - 66 x 40 feet with a trunk diameter of 2 feet. It is also known to grow at Nichols Arboretum in Ann Arbor, Michigan. An excellent lawn or street tree.
The handsome pinnate leaves, up to 16 inches in length are crowded towards the branch tips and are composed of 7 to 15 opposite arranged sharply toothed leaflets up to 5 x 2 inches in size.
The foliage is glossy deep green turning brilliant orange and scarlet during autumn. On shady sites the foliage may be lighter green during summer and yellow in autumn. The fall color persists over a long season and is often very attractive even in mild climates.
The small, bright yellow-green flowers are borne in clusters up to 8 x 8 inches in late spring and are followed by attractive red to black berries to 0.2 inches in autumn.
The smooth bark is gray-brown to red-brown.
Hardy zones 4 to 8 in full sun on moist, fertile loamy soil. Prefers acidic to neutral soil but is lime tolerant. Also urban and drought tolerant. Seed source may be important in determining cold hardiness, it has frozen back multiple times and remained barely more than a small shrub at Dominion Arboretum in Ottawa, Canada. Quassia prefers hot summers and grows much slower and smaller in the British Isles though reported to be fast growing in the Pacific Northwest. Propagated from seed sown in autumn. The seed needs 4 or more months of cold stratification to break dormancy. Not prone to pests or disease and in fact extracts from the wood are used as a natural insecticide.

* photos taken on October 17 2010 @ U.S. National Arboretum, D.C.





* photo of unknown internet source


TROPICAL PICRASMA

Picrasma excelsa ( Quassia Wood )
An erect tree native to the Caribbean that reaches a maximum size of 82 x 50 feet with a trunk diameter of 3.5 feet. It is threatened by rainforest destruction in its native range. It also makes an excellent lawn and street tree in the landscape.
The pinnate leaves, up to 14 inches in length are crowded towards the branch tips and are composed of opposite arranged oblong leaflets up to 5 x 2 inches in size.
The foliage is glossy bright green
The small, bright yellow-green flowers are borne in panicles in late summer and autumn are followed by attractive glossy copper-red berries in autumn.
The whitish bark is smooth.
Hardy zones 9 to 12

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