Introducing Heptacodium miconioides

By Alex Henderson, Curator of Living Collections, Royal Botanical Gardens

With the sun having recently crossed the celestial equator and welcoming the autumnal equinox, many of us are now firmly in fall mode and enjoying the herbaceous floral flowers and colours associated with this time of year. There is however, at least one rebel genus without a cause in RBG’s living collections that is a woody plant and flowering profusely despite the time of year. Heptacodium miconioides (Seven-son Flower) is small deciduous shrub or tree endemic to China, which as of writing in early October, is putting on a magnificent floral display. Under floral observation the viewer feels remarkably transported back to the flowering characteristics of trees and shrubs of spring.

Discovered in Hubei Province in 1907 by Ernest Wilson on a collection trip for the Arnold Arboretum, H. miconioides was later (in 1916) determined by his colleague, Alfred Rehder. to be a new species. It somehow remained largely unrecognized for 60-plus years but in 1980, new seed was collected by the Arnold Arboretum working alongside the Chinese Academy of Sciences from a specimen at Hangzhou Botanical Garden. This was the first introduction of this charismatic plant into North American cultivation and in 1981 Hangzhou Botanical Garden distributed additional seed to other botanical gardens globally. In 1998 the plant was assessed by the International Union for Conservation of Nature. Data gathered for the Red List of Threatened Species revealed that H. miconioides only occurs in two locations in Hubei and is only found in small numbers. Due to threats from annual and perennial non- timber crops, livestock farming, and logging, an evaluation status of Vulnerable was applied to the wild population.

Due to its relatively recent introduction in horticulture, H. miconioides is a plant considered to be unusual in cultivation – one of the reasons it is not more widely cultivated in parks, green spaces, residential and commercial landscapes. Upon first introduction, it comes as a surprise to note a woody plant flowering in September and October. This makes it a more valuable addition for extending the season of interest as its size, lateness of flowering and fragrant blossoms makes it an ideal addition to a variety of garden situations. It is well suited as a specimen plant in shrub or mixed borders in full sun or partial shade, and it can be considered a low maintenance plant. It is also a bee, butterfly and hummingbird magnet, providing vital support for pollinators. Typically grown as a multi-stemmed fountain shape, it can reach a height of 4.5–6 metres (15-20 feet) and a spread of 3.5 meters (10 feet) and can, if required, be trained as a single stem specimen. Flowers are profuse, creamy white and pleasingly fragrant and followed by small, purple red fruits topped by spectacular bright pink calyces which last late into fall and are perhaps even showier than the flowers. The bark, which is a tan colour, peels to reveal brown inner bark and so provides satisfying winter interest. Emerging in May, its leaves are large, deciduous, heart-shaped with deep venations and tough, having few, if any, pest or disease problems. It is tolerant of a wide range of soils, is extremely cold hardy and easily tolerates winters in the GTHA. All of the original specimens planted at the Arnold Arboretum in 1980 are still alive, suggesting Seven-son Flower has a life span greater than 40 years.

One the most spectacular plantings at RBG is in the White Garden in Hendrie Park where it thrives in full sun and consistently performs well. When visiting Seeing the Invisible make sure to make time to stop and admire this magnificent planting as it is a work of art itself. Given the many merits described above, it is no wonder that this versatile but underused plant has gained the Royal Horticultural Society’s Award of Garden Merit. Heptacodium miconioides is nothing short of outstanding and thankfully it is now available at local nurseries to add season-long interest in your garden.