Dr. Bob Gilbert – Columnist

Dr. Bob Gilbert

I have just finished reading an interesting book “The Overstory” by Richard Powers.  The author writes about trees.  He says “no one sees trees, trees are mostly invisible as we see only wood, shade, blooms, nuts, branches about ready to crush our roofs, cash crops, pretty fall foliage, fruit, ornamentation and obstacles that block our roads and ski slopes.  This is not our world with trees in it but we live in a world of trees where humans have just arrived.”

In early summer it is easy to spot the pink blooms of a tree called Mimosa.  Most of us have never really looked at its entire structure and never noticed it when not in bloom.  Its scientific name is Albizia (al biz a) julibrissin (ju li bri sin).  The genus name Albizia is used to acknowledge an Italian nobleman Flilppo Albizi who introduced this tree to Europe in the mid-18th century.  Julibrissin comes from a Persian word meaning silk flower.  The common names are Mimosa or Silk Tree.  However, there are other trees such as Acacia that are also known as Mimosa.  This can get a little confusing which creates a good argument for using scientific names.  The Japanese name for this tree is Nemunoki which means Sleeping Tree. Its deciduous foliage tends to furl up or close at night.  The flowers look like they are composed of pink threads.  The color and fragrance attracts bees, butterflies and hummingbirds.  It puts on quite a show by blooming throughout the summer.  It originally came from Iran, China, Japan and Korea and was introduced here in 1745.

This tree was often planted for its unique delicate leaf texture, its flowers and its horizontal canopy that all make it special.  It’s canopy always reminds me of something you would see in Africa.  In fact, to many this tree looks tropical. It is a fast grower, can stand hot summer temperatures and does not need a lot of water.  It is another understory tree that creates high or dappled shade.

With all these wonderful attributes you would wonder why it is not for sale or cultivated more often. One reason is that it is short-lived. Some but not all of these trees are susceptible to a vascular wilt which is a fungus disease for which there is no treatment available.  Also, it produces great quantities of light weight seeds that can be carried by wind great distances.  Thus, this tree is listed invasive because it self-seeds so often.  In fact, the only ones we see here are from wind distributed seeds.

Another common name for this tree is The Tree of Happiness.  The flowers and bark are highly favored by the Chinese who prepare extracts to treat anxiety, stress, depression. In addition, it is used as a sedative.  As a natural remedy it is more effective than St. Johnswort.

There is a cultivar called “Summer Chocolate” which has deep burgundy foliage and both pink and white flowers. Another cultivar “Rosea” is smaller in height with the same pink flowers.  “Rosea” has received the Royal Horticultural Society’s Award of Garden Merit.  The cultivar “Ernest Wilson” is a cold tolerant cultivar. “Union” is a cultivar that is reportedly disease resistant but so far may not be available.  It was tested in Union, S.C., and demonstrated wilt resistance.

The good news is that in the United States work is being done to develop a sterile plant that does not produce seeds and that has resistance to the wilt fungus.  So, the future looks promising for this beautiful tree.  Until seedless and disease resistant cultivars are introduced this would not be a good long-term choice for a landscape.  It could survive for at least 10-15 years and maybe longer.   Fortunately, it does not appear to be a seriously invasive as it does not aggressively compete with our native plants

Take a quiet moment and look at the entire structure of Albizia julibrissin.  Whether in bloom or not it is a lovely tree with interesting bark, a tropical looking canopy with very special foliage.  Certainly, it would not be appropriate as a foundation plant.  But it would be great as a secondary landscape feature.  Does it really matter that it is a short -lived tree?  We have pets that live for about the same amount of time.

Dr. Bob Gilbert, now living in Franklin is cofounder of Smith Gilbert Gardens in Kennesaw Ga.

Karen Lawrence is a prefessional photographer of botanical subjects and wildlife is from Franklin, N.C.