Seven Times the Interest – the Seven-Son-Flower

By Bruce Crawford, Manager of Horticulture Morris County Parks Commission.

On numerous occasions I have heard homeowners question the worthiness of hiring a professional to help with designing their garden. After all, what could be so challenging about arranging plants? One challenge for me was understanding the flexibility of large shrubs, whose statures approach 20′ in height. Typically, they are relegated to screening or a shrub border. However, for some the lower limbs can be removed, magically transforming a shrub into a small tree. Several plants come to mind, but one of the best candidates for this treatment is Seven-Son-Flower or Heptacodium miconioides.   

Seven-Son-Flower is a member of the Honeysuckle Family or Caprifoliaceae and is a monotypic plant, meaning the genus only has one species. It is a native of China and has an interesting history of how it arrived in our gardens. The most notable discovery was by the renowned plant collector Ernst Henry Wilson (1876-1930) in 1907. Noting the plant was very rare, he only found two specimens perched on cliffs near 3,000 feet in elevation in Western China. He called the plant Heptacodium, honoring the whirl of 6 flowers surrounding what appears as a seventh bud, since hepta is from the Latin for seven while codium refers to a poppyhead. The radiating lines visible atop a poppy seed structure somewhat resemble the structure of the flower. The specimens were sent back to the Arnold Arboretum where the genus and species name were published in 1916 by the German born botanist Alfred Rehder (1863-1949). Rehder selected the genus epithet from the physical similarity to the genus Miconia, a group of tropical trees and shrubs.

Interestingly, Wilson was not the first to ‘find’ Heptacodium in the wild. In 1877 William Hancock (1847-1914), an Irish botanist who served as a customs agent for the Chinese Imperial Maritime Customs Service found a plant near 3,000 feet in Eastern China. Dried specimens of the plant made their way back to Kew, the Royal Botanic Garden in England where they remained unnoticed until 1952. The English botanist Henry Kenneth Airy Shaw (1902-1985) was intrigued by the specimens and believing this plant to be unique from that described by Rehder, he named the species Heptacodium jasminoides as the flowers strongly resemble Flowering Jasmine.

Finally, on November 1, 1980 a living plant was once again seen and seed collected by American botanists at the Hangzhou Botanical Garden in Eastern China. The collection was part of the Sino-American Botanical Expedition, whereby plants were exchanged between China and the United States. Seed was sent back to the Arnold and National Arboretum, who in turn shared small plants with the New York Botanic Garden. It was from these three Arboreta that the plant was finally introduced into the nursery trade under the name of Heptacodium jasminoides. As mentioned, Heptacodium is a monotypic plant and in 2011 it became apparent the two species were in fact one in the same. In such instances the initial name becomes the accepted name and the species epithet selected by Rehder prevailed.

For designers and homeowners, the challenge with new introductions is not so much the name, but determining how best to use the plant. Growing to 20′ tall and 15′ wide, Heptacodium was introduced into the American trade as a large upright shrub. However, in China it was described as a small tree with an arching branching habit! This is one of those shrubs whose shape and use in the garden is truly determined by how the plant is trained. Rather awkward in youth with stems growing at irregular angles, 2-3′ tall plants should be pruned to one or at most, 3 dominant stems that show promise for not growing into each other or rubbing with age. 

The main summer attribute is the floral display. During July, the flower buds appear at the stem tips, but they merely serve to tantalize the gardener since they do not finally open until late August! The white flowers are individually ½” in diameter, but they are amply produced in whirls of six, providing a glowing display against the dark green foliage. The seventh central bud mentioned prior is actually an extension of the floral stem and does not yield a flower. Each flower consists of 5 white petals surrounding 5 yellow anthers with a central green stigma. In addition, the flowers bear a sweet fragrance that is easily detected by people and pollinators alike, especially honeybees! As the flowers fade, the calyx or outer set of leaves that initially covered the flower buds gradually enlarges throughout October and turns red. They are highly ornamental and give the appearance of bright red fruit clusters from a distance. Each bright red calyx sits atop a single seed. Although they are designed to be distributed by the wind, seedlings are rarely seen. 

 

Not to be outdone by the floral display, the bark also has a magnetic appeal for gardeners. As the stems and trunk expand, the medium brown to gray-brown bark exfoliates or peels in long thin papery strips, revealing a light tan inner bark. Obviously, removing the lower limbs to expose this very ‘appealing’ bark is a great reason to grow the plant as a small tree! Consider planting it outside a room with a prominent winter view or next to a major path, allowing the bark to be appreciated year-round!  Best in full sun, plants are reliably hardy from zones 5-9 and are incredibly tolerant of various soil types and pH levels. 

The potential of large shrubs for enhancing the garden sadly remains unrealized by many gardeners. Considering how best to reveal the ornamental attributes of a plant occasionally requires insight from professionals who have studied proper cultural techniques. It took me a long time to understand the versatility of plants like Seven-Son-Flower, which provide the garden with seven times the beauty of many small trees and shrubs!