Friday, October 4, 2013

Heptacodium miconiodes: A Great But Hard To Find Ornamental Tree.

15' specimen as the rosy sepals are starting to emerge after the
flowers.  A 'second' flowering.  ©2013 BDG
While driving through my neighborhood a few weeks ago I came across a tree not often seen in the landscape.  It caught my eye as there are very few trees flowering in September and, knowing the family living in the house, I was confident that I wouldn't be shot for stepping on the lawn for a closer look.  The tree was Heptacodium miconiodes or Seven Son Flower.

This is an unusual and somewhat rare tree in the garden and apparently it is even rarer in its natural habitat in China.  It was first brought to the United States at the turn of the twentieth century, but it is believed that the first major introduction came in 1980 when a team of Botanists, several from Arnold Arboretum here in Boston, travelled to China and came back with seeds.  An article from 1986 in Arnoldia covers many of the details of the expedition and the ensuing process to propagate for distribution.

A small tree in flower. ©Morton Arboretum
Seven Son Flower is a medium sized tree that is estimated to mature in the 15-25' range and almost as broad,  and is hardy from zones 5-8 but seems to do best in the cooler climates of southern New England.  In its native habitat it is a woodland tree and tends to be open, and awkward in its branching.  In greater sunlight it tends to be a little more dense.  The best specimens I have seen benefit from some pruning to accentuate the awkwardness, keeping the branches that want to spread from getting too weak and not able to support snow and ice in New England.  

Every indication is that it is not a particularly drought-tolerant tree, so some shade, organic matter in an acid soil with good moisture will ensure a tree that thrives throughout the season.

The flowers and follow-up display provide interest from late summer and through October.  Only a few trees that I know in New England flower late in the year: Oxydendrum(Sourwood), Maackia(Amur Maackia) and Prunus autumnalis (fall flowering Cherry).

The flowers finishing and the rosy sepals starting in
late September.  ©2013 BDG
The flowers come in groups of six with a seventh flower coming at the end, hence the name 'hepta' and on a happy specimen they cover the tree and carry a wonderful fragrance.  As part of the family, Caprifoliaceae or Honeysuckle Family, it is no surprise that they are fragrant, and as you look closely at the image you can see six flower buds that open into long narrow tubular flowers, similar to honeysuckle.  Other plants in this family are Weigela, Abelia, Honeysuckle and Viburnum.

The rosy sepals emerging from the ripening fruit
in October. ©2013 BDG
The show is just starting with flowers which can last through September.  Once the flowers are mostly finished, another part of the flower called the sepal which usually goes unnoticed, starts to grow and form a beautiful rosy-red, "flower-like display".  It appears that the tree actually has two distinctly different flowering events.  The colored sepals carry into the fall when leaves on trees start to change.  

The leaves in spring come out a beautiful green and mature to a dark green.  The peeling bark is another beautiful trait of the tree as it is a light brown and peels in long strips and provides  great winter interest.
Very cool peeling bark. ©2013 BDG

The only part of this tree that does not exceed expectations is the lack of fall color on the leaves.  They tend to wither and sometimes get a little yellow color, but there is nothing exceptional to compete with our fantastic New England leaf color display.

When I think of some of the best ornamental trees like Stewartia pseudocamellia, Flowering Dogwoods and Japanese Maples, Heptacodium should be in this group.  Unfortunately, the tree is not readily available in the trade.  Years ago while on a field trip with a company, we went to Haskell Nursery down in New Bedford and I remember seeing many Heptacodium for sale.  Allen Haskell was one of the growers who was integral in starting the distribution of this plant in the 1980s.

This spring while at Stonegate Gardens in Lincoln, MA I saw several wonderful 8-10' B&B specimens for sale.  They are not expensive as they are easy to propagate from cuttings and grow quickly.  

A Beautiful 8-10' specimen for sale at
Stonegate Gardens in Lincoln, MA
in June.  ©2013 BDG
I think this tree can carry itself as a stand alone specimen with some proper pruning, or it can be used in the border or on the edge of a foundation.  Since it is a fall flowering tree, it is critical not to prune during the growing season while it is producing its flower buds.  This is a late fall and winter pruning tree.  If you read my recent post on the Franklinia tree that was pruned every summer by a mow and blow crew, then you understand how important it is to know when AND how to prune your trees.  This client of mine who had this beautiful Franklinia for several years had no idea that it flowered because the flower buds were pruned off every summer before they opened.

If you are looking for something different and a boost of color and interest in your late summer and fall garden, then Heptacodium may be a cool and different choice.

Another perspective on the peeling bark.
©2013 BDG

The sepals fully emerged in October.  ©2013 BDG.