Horticulture Highlight: Heptacodium miconioides
“…but if a plant has beautiful leaves it is, I think, the best reason for growing it. If it has good flowers as well, that makes two good reasons.”
Heptacodium miconioides, seven-son flower is a 15-20 foot-tall, deciduous, small tree or large shrub which, indeed, has attractive leaves and good flowers. The timing of flowering in late August and September provides nectar for butterflies and bees long after most other ornamental trees and shrubs are past blooming.
This lesser known plant is a member of the Caprifoliaceae or honeysuckle family and is native to China. It was first collected for Western science in 1907 as herbarium [cut and pressed dry] specimens by the prolific plant explorer Ernest Henry Wilson (1876-1930) on his third of four remarkable Chinese expeditions. Viable seed was not collected at that time and it was only after a 1980 re-introduction and subsequent nursery production, that this plant finally became available in the mid-1980’s.
Its genus was named by renowned taxonomist, Alfred Rehder (1863-1949), using the Greek hepta for seven and codium for poppyhead as the small single flowers occur in a whorl of six surrounding a central seventh blossom. These whorls of seven tiny, cream-white flowers are deliciously fragrant and abundantly produced in clusters when planted in full sun settings, but will nonetheless sweeten the air, in fewer numbers, when grown in the shade.
The leaves are 3- to 6-inches long and 2-inches wide, have an entire margin [non-toothed edge], with rounded bases and pointed tips. The handsome, dark-green leaves have three distinct parallel veins, occur opposite each other, are pest and problem free, and may cling to the stems into November without offering a colorful foliage display.
There is an outstanding autumn display, though, which is uniquely provided by the sepals of the flowers. Sepals on many flowers are visually inconspicuous. Foliage-like elements outside of the petals that sometimes persist as a fruit matures (think of the five tiny sepals on the bottom of an apple). Heptacodium sepals surrounding its flowers also begin as tiny and green. As the small fruits develop these sepals persist, elongate, and change color, green to pink to burgundy mimicking a second bloom of a different color and more spectacular then the flowers.
Additionally, the light tan-colored bark exfoliates in small paperlike strips producing a striking effect with heightened ornamental value in the winter landscape. Thus Heptacodium is truly a multiple-season interest plant. This has been affirmed by it being a winner of the Cary Award, an award created to recognize underutilized woody plants for New England that exhibit superior landscape appeal in two or more seasons, are pest resistant, and available for use.
While the 1907 herbarium specimens provided great scientific value they were incomplete for full visual or fragrant characteristics. When Mount Auburn planted our first Heptacodium in 1988 we were continuing our long tradition of using horticulture as both art and science. This began with our 1831 founding as a partnership with the Massachusetts Horticultural Society and continues today with exciting plans to build a new Horticulture Center to further this legacy. On your next visit to Mount Auburn, while enjoying our whole living collection of plants with timeless appeal, look for seven-son flower growing on Lime Avenue, Willow Avenue, Spellman Avenue, and Raven Path.
*This Horticulture Highlight was originally published in the September 2010 issue of the Friends of Mount Auburn electronc newsletter.