Plant of the Month

 

Plant of the Month Archive

A Winter Winner Whose Time has Come!

Winter is the season for appreciating trees and shrubs in a new light.  Plants with evergreen foliage naturally take center stage, but there are numerous other winter winning qualities that add seasonal interest.  For example, the bark of trees or shrubs.  Whether exfoliating or simply colorful, bark is always a garden asset, but it becomes all the more important during those bleak winter months.  Amur Maackia, botanically named Maackia amurensis is a little known tree that was introduced into cultivation in 1864.  It not only has great bark, but possesses a solid constitution that deserves far closer attention after 150 years!

Maackia is a member of the pea family or Fabaceae and has 12 species, all of which are native to Eastern Asia.  The genus name honors Richard Otto Maack (1825-1886).  Maack was a Russian naturalist who explored the Russian Far East.  In 1855-56, he explored the very cold regions of the Amur River Valley, which forms the boundary between Russia and Northern China.  One of the plants he discovered during this exploration was Maackia amurensis, with the species epithet recognizing its place of origin.  The plant was named and described by Franz Josef Ruprecht (1814-1870).  Although born in Austria, Ruprecht spent his life practicing medicine and botany in Russia, describing many plants collected in the far eastern regions of Russia.  He described Amur Maackia in 1856 after receiving specimens from Maack’s journey to the Amur River Valley.

Maackia amurensis is a mid-sized tree, slowly reaching 40’ in cultivation, but can grow to 60+ in the wild.  It has compound leaves arranged alternately along the stem, with each 8-12” long leaf having between 7-13 elliptically shaped leaflets.  Although the foliage is deep green in summer, it is covered with silky white hairs as it unfurls in the spring, giving the plant a very attractive silvery glow.  In early to mid-July, the tips of the branches yield clusters of 4-8” long flower racemes that are clothed in ½” long, off-white flowers (as pictured in the image above and below).  The flowers have a faint yet pleasant fragrance, reminiscent of newly cut POMgrass.   The flowers are not overly dramatic, but since they bloom at an unusual time of the year for a tree, they provide a more than welcome addition to the garden! The flowers are followed by flat, 1½”-2” long seed pods.  Although the seeds are viable, they require a short treatment of boiling water in order to soften the seed coat and I have not seen any seedlings appearing in Rutgers Gardens.  Of course for winter appeal, the rich coppery-brown bark of Maackia takes center stage.  Not only is the color very cheerful and luminescent, but it peels off the trunk and branches in curious and attractive vertical curls (pictured below). 

As is typical of slow growing trees, the wood is dense and relatively hard.  The young sapwood is a light tan in color, but the older heartwood assumes a much darker color and is valued for furniture and other hardwood uses.  It is also extremely decay resistant and much like its North American cousin, Black Locust, it is used for fence posts in Asia!  However, not only is the wood tough, but so is the tree – it is able to grow and thrive under the most difficult of conditions!  Since it is in the pea family, it is able to fix its own nitrogen and can survive in more nutrient poor soils.  It is also adaptable to alkaline and acidic soil conditions.  It appears to be adaptable to extremes in soil moisture since in China, it has been found growing adjacent to ponds and lakes where the seasonally high water table comes close to the trunk of the plants.  However, these plants show little to no stress during summertime droughts when the water in the ponds and lakes recede dramatically.  I have seen it planted in soil pits that contain tPOMopsoil, but the surrounding patio areas feature compacted subsoil with gravel underlying the stonework.   Over the past 15 years, the roots have long since extended out into the subsoil, yet the trees look fantastic.  I suspect there are many gardens with similar conditions in need of a tough tree!  It is a bit finicky about temperatures, preferring the cooler summer temperatures found in the regions of Zones 3-7. 

Although there are relatively few selections of Maackia, ‘Starburst’ is a cultivar introduced in 1998 by Princeton Nurseries, the famed shade tree nursery of Kingston and Allentown NJ.  The plant was selected by Richard Hesselein who was President of Princeton Nursery and is currently President of Pleasant Run Nursery.  The plant features a very uniform canopy shape, a naturally straight trunk and resistance to leaf hopper damage, which can be problematic under nursery conditions as leaf hoppers stimulate a proliferation of small stems at the tips of branches called Witches Broom.  The plant produces starburst shaped flower clusters at the tip of nearly every branch, the shape of which provided the inspiration for the cultivar name!  All the images above are of ‘Starburst’!

Obviously, Amur Maackia is one tough plant with many benefits for the gardener.  Its attractive foliage, flowers and bark, paired with its tough constitution and residentially appropriate mature size raises the disconcerting question as to why it has spent the past 150 years in obscurity?  It is certainly a plant whose time has come!