Heptacodium

Heptacodium miconioides, the seven son flower, is a species of flowering plant. It is the sole species in the monotypic genus Heptacodium, of the honeysuckle family Caprifoliaceae. The common name "seven son flower" is a direct translation of the Standard Chinese name 七子花 qi zi hua.

Heptacodium
Heptacodium miconioides, Mt Auburn Cemetery, Cambridge, Massachusetts, USA
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Dipsacales
Family: Caprifoliaceae
Subfamily: Caprifolioideae
Genus: Heptacodium
Rehder
Species:
H. miconioides
Binomial name
Heptacodium miconioides
Rehder
Synonyms[2]

Endemic to China, this species was discovered for Western horticulture in 1907 by the British plant hunter Ernest Wilson on behalf of the Arnold Arboretum. It was growing on mountain cliffs at 'Hsing-Shan Hsien' in present day Xingshan County in the west of Hubei Province in central China.[3][4] Considered rare even at that time, only nine populations are known to remain in the wild (e.g. one on Tiantai Mountain),[4] all of them in Anhui and Zhejiang provinces and threatened by habitat loss.[5] The species is now under second-class national protection in China.[6] The Sino-American Botanical Expedition of 1980[7] collected viable seeds and sent them to the Arnold Arboretum where it was found to be readily cultivated. The plant is now grown as an ornamental around the world.


Description

Heptacodium miconioides is a deciduous large shrub or small tree, typically growing to a height of 4–9 m (13–30 ft). The bark of the trunk is papery and thin, light tan in colour, and exfoliates in strips or sheets. The upright, spreading, quadrangular branches give the plant a rounded, often irregular shape. The dark-green cordate leaves are opposite, 8–10 cm long by 5–6 cm wide, with entire margins and deeply impressed venation running parallel to the margin.[7] In September, H. miconioides produces large shows of small fragrant white blooms attractive to butterflies and bumblebees,[8] the flowers five-petalled, < 13 mm across.[9] When the white corollas have fallen, the calyces develop into deep red expanded lobes which persist into November. The plant may be found in scrub, woodlands, and on the margins of broadleaved evergreen forests, often on cliffs, at altitudes of 600-1000 metres.[10]

Six flowers, not seven

Noted plantsman John Grimshaw, director of the Yorkshire Arboretum, relayed the following observation of H. miconioides from distinguished botanist Allen J. Coombes, (formerly of the Hillier Gardens and currently coordinator of scientific collections at the University Botanic Garden Puebla, Mexico):

'Seven' is actually misleading, for the flowers in each capitulum are held in two rows of three clustered around a central bud, which is not a flower bud but in fact a continuation of the inflorescence axis, which will push up as the flowers fade and develop a new ring of six flowers, again around a central bud. Three such iterations have been observed.

Cultivation

Readily propagated from either seed or by softwood cuttings, the species has since become widely available in North America and Europe, and was stocked by 26 nurseries in the UK alone in 2011. H. miconioides is extremely hardy, and tolerant of temperatures as low as −35 °C (−31 °F). It is also fast-growing, and can reach a height of 3 m (9.8 ft) in just five years; it is also very shade tolerant.[7] All six of the first H. miconioides planted in the United States in 1980 at the Arnold Arboretum are still alive, indicating an expected lifespan greater than 40 years.[11] This plant has gained the Royal Horticultural Society’s Award of Garden Merit.[12][13]

Notable trees

In the UK, a specimen 8 m high (2012) planted in 1981 grows in the Flagpole Bed alongside Jermyn House at the Sir Harold Hillier Gardens, Ampfield, near Romsey.

Etymology

The generic name of Heptacodium has sometimes been said [14] ( erroneously ) to mean 'seven bells' ( with a second element derived from Greek κώδων ( codon ) - 'bell' ), but was in fact coined by Arnold Arboretum taxonomist Alfred Rehder from the Greek κώδειά ( codeia ) - 'poppy head' with the prefix έπτά ( Hepta- ) 'seven', giving the meaning 'having seven structures resembling poppy heads'. The specific epithet miconioides alludes to the similarities of the plant ( particularly its boldly-veined leaves ) to certain species belonging to the unrelated genus Miconia ( family Melastomataceae ).

The common name in Standard Chinese 七子花 ( qi zi huā ) is composed of the characters 七 ( qi ) 'seven', 子 ( zi ) 'son' / 'child' and 花 ( huā ) 'flower' - whence 'Seven Son(s) Flower' ( 'Flower with seven children' ). Approximate pronunciation ( not allowing for tonality of Chinese language ) 'Chyee-dzu-waa'.[15]

Medicinal potential

Recent tests have demonstrated that extracts from the plant possess antibacterial activity.[16] The leaf blades of Heptacodium have been found to contain flavonoids, tannins, alkaloids, saponins, lignin and chlorogenic acid.[17]

  • Characteristic peeling bark of mature specimen.
  • Four trunks of mature specimen, side view.
  • Bifurcating trunks ( with fifth subsidiary trunk ) of mature specimen, viewed from above.
  • Single leaf, showing characteristic, three, parallel, longitudinal veins.
  • Spring foliage in canopy of mature specimen, viewed from beneath.
  • Close-up of small, scented, white flowers in late Summer / Early Autumn.
  • Pink colouration of fruiting calyces.
  • Close-up of fruiting Calyces in late October.

References
  1. World Conservation Monitoring Centre (1998). "Heptacodium miconioides". IUCN Red List of Threatened Species. 1998: e.T32355A9700631. doi:10.2305/IUCN.UK.1998.RLTS.T32355A9700631.en.
  2. The Plant List, retrieved 24 September 2015
  3. Sargent, Charles Sprague (1916). Plantae Wilsonianae : An enumeration of the woody plants collected in western China for the Arnold Arboretum of Harvard University during the years 1907, 1908, and 1910 by E. H. Wilson, Volume 2. Cambridge [Mass.]: University Press. pp. 617–619.
  4. Heptacodium miconioides Rehder - online article in the series 'Tree of the Year' by Grimshaw, John http://www.dendrology.org/publications/tree-of-the-year/heptacodium-miconioides-2012/ Retrieved 11.14 on 16 May 2018
  5. Lu, H. P.; Cai, Y. W.; Chen, X. Y.; Zhang, X.; Gu, Y. J.; Zhang, G. F. (2006). "High RAPD but no cpDNA sequence variation in the endemic and endangered plant, Heptacodium miconioides Rehd. (Caprifoliaceae)". Genetica. 128 (1–3): 409–417. doi:10.1007/s10709-006-7542-x. PMID 17028968. S2CID 25707962.
  6. "National key protected wild plants (first batch)". Nature Reserve of China. 2004-07-10. Archived from the original on 13 April 2012. Retrieved 13 April 2012.
  7. Gary L. Koller (1986), "Seven-Son Flower from Zhejiang: Introducing the Versatile Ornamental Shrub Heptacodium jasminoides Airy Shaw" (PDF), Arnoldia, 46 (4): 3–14
  8. https://afrenchgarden.wordpress.com/2012/09/02/heptacodium-jasminoides-the-bumble-bee-tree/
  9. Stebbings, G. (2011). Autumn Glory - Late Developers. Garden Answers, p. 48, September 2011. Bauer Media, London.
  10. Heptacodium miconioides Rehder - online article in the series 'Tree of the Year' by Grimshaw, John http://www.dendrology.org/publications/tree-of-the-year/heptacodium-miconioides-2012/ Retrieved 11.14 on 16/5/18
  11. "Arnold Arboretum Seven Son Flower Bio". arboretum.harvard.edu. Retrieved 4 August 2020.
  12. "RHS Plantfinder - Heptacodium miconioides". www.rhs.org. Retrieved 3 March 2018.
  13. "AGM Plants - Ornamental" (PDF). www.rhs.org. Royal Horticultural Society. July 2017. p. 47. Retrieved 2 March 2018.
  14. e.g. by the Missouri Botanical Garden http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=k450 Retrieved at 11.41 on 17/5/18
  15. Google translate. Language : Traditional Chinese
  16. JIN Ze-xin, LI Jun-min ( Ecology Institute, Taizhou University, Linhai 317000, Zhejiang,China ) Anti-bacterial activity of extracts from Heptacodium miconioides March 2006. http://en.cnki.com.cn/Article_en/CJFDTOTAL-ZJLX200603013.htm Retrieved 12.14 on 27/4/18
  17. YANG Bei-fen, SHAO Hong, JIN Ze-xin ( Ecology Institute of Taizhou University, Linhai, Zhejiang 317000,China ) Analysis of Secondary Metabolism Contents in Leafblades of Heptacodium miconioides http://en.cnki.com.cn/Article_en/CJFDTOTAL-XBLX200602035.htm retrieved 00.56 on 28/4/18.
  • Airy Shaw, H. K. (1952). A second species of the genus Heptacodium Rehd.(Caprifoliaceae). Kew Bulletin 1952, Number 2, pages 245-246.
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