Download Seven-Son Flower - Arnold Arboretum

Seven-Son Flower
Heptacodium miconioides
Painting of calyces by Amy Eisenberg
September Tree-of-the-Month
Hepta- means seven in Greek.
The number refers to the
number of flower heads that
bloom in each cluster on the
seven-son flower.
Septem- also means seven
but in Latin. This is the root
of September which was the
seventh of ten months on the
old Roman calendar.
125 Arborway
Boston, MA 02130-3500
617-384-5209
www.arboretum.harvard.edu
© 2014 The President and Fellows of Harvard College
Look closely at the flower
The flower buds of seven-son flower form in early summer and increase in size ever so slowly,
bursting forth with creamy white flowers by the end of August. In Massachusetts, the flowering
period is quite long, lasting until early October.
Through simply looking for food, thousands of species of insects (and animals) help plants to
reproduce. Most people know that bees are important pollinators, but that’s not all. Many
species of butterflies, bats, birds, moths, flies, and wasps are also pollinators. In September at the
Arboretum, there are relatively few plants for pollinators to feed upon so the fragrant seven son
flowers are a favorite.
When flowering is over, the calyces (collective term for sepals) do not fall off but persist and
continue to grow. The fruits develop from the flowers; light green at first, they ripen to a rosepurple. A large cluster of sepals is more spectacular than the blossoms at the peak of flowering.
The rich purple color remains attractive for several weeks as the fruits continue to ripen. At full
maturity, the fruits turn tan and slowly fall away.
An introduction
In 1916, the Arboretum taxonomist, Alfred Rehder first described this plant collected by E.H.
Wilson on his 1907 expedition to western China. With its oppositely arranged leaves, the genus
was assigned to the Caprifoliaceae family to which the viburnums and honeysuckle belong.
In 1980, several American botanists botanists – including Steve Spongberg from the Arnold
Arboretum – collaborated with a team of Chinese scientists for the Sino-American Botanical
Expedition. At the Hangzhou Botanical Garden the botanists were excited to see a living plant of
Heptacodium and requested seeds for propagation. Today, the Arboretum has six plants from the
expedition growing out of doors; follow the letterboxing directions below to see five of these. The
Arboretum helped to distribute this rare Chinese plant across North America where today it is
more abundant than in its homeland.
Letterboxing!
Letterboxing is a fun way to explore the seven-son flowers and the Caprifoliaceae family at the
Arboretum. For more information on letterboxing, go to www.letterboxing.org.
To find the letterbox and 5 of the plants from the 1980 expedition, follow these 7 steps:
yy Start at the intersection of Bussey Hill and Valley Roads, have a seat on the bench.
yy Cross the road to the map table and walk to the newly planted Viburnum trilobum #361-2006*A.
yy Continue 15 steps to Viburnum rhytidophyllum ‘Roseum’ #133-67*A.
yy Continue 30 steps to the large London plane tree planted in 1894 #1659*A.
yy Turn left toward the Centre Street Gate and take 30 steps. You will be among 3 seven-son
flowers.
yy Take 15 more steps crossing the gravel path and you will be between 2 seven-son flowers.
yy Finally, take 25 steps crossing the road to the final one #181-96*A. The letterbox is hidden on
the ground behind the trunk. Follow the directions inside, and leave everything as you found it.