Buddleja colvilei is endemic to the eastern Himalaya; discovered by Hooker in 1849, he declared it 'the handsomest of all Himalayan shrubs.'Bean, W. J. (1914). Trees and shrubs hardy in the British Isles. 7th Ed. 1950, Vol. 1, p. 320. In 1896 the species was awarded the RHS First Class Certificate (FCC),Hillier & Sons. (1990). Hillier's Manual of Trees & Shrubs, 5th ed.. p. 47. David & Charles, Newton Abbot. given to plants 'of outstanding excellence for exhibition'.Royal Horticultural Society, (2005). RHS Plant Finder 2005-2006, Dorling Kindersley.
Description
B. colvilei is a deciduous large shrub or small tree which can grow > 13 m, often single stemmed. The flowers are arranged in drooping panicles, 15–20 cm long by > 8 cm wide, rose pink to crimson, but often white within the corolla tube. The flowers are among the largest of any in the genus, and appear in June. The leaves are < 25 cm long, narrow, shallowly-toothed, and tapered at either end. This species has a high degree of polyploidy with a correspondingly high chromosome number of 2n = 152–456 (8x–24x).Chen, G, Sun, W-B, & Sun, H. (2007). Ploidy variation in Buddleja L. (Buddlejaceae) in the Sino - Himalayan region and its biogeographical implications. Botanical Journal of the Linnean Society. 2007, 154, 305 – 312. The Linnean Society of London.
Cultivation The shrub is not entirely hardy in the UK, and can only be reliably grown outdoors along the Atlantic coast. Hardiness: United States Department of Agriculture zones 8–9.Stuart, D. D. (2006). Buddlejas. RHS Plant Guide. Timber Press, Oregon.
Cultivars Buddleja colvilei 'Kewensis', distinguished by its dark red flowers.
References
Leeuwenberg, A. J. M. (1979) The Loganiaceae of Africa XVIII Buddleja L. II, Revision of the African & Asiatic species. H. Veenman & Zonen, Wageningen, Nederland. Phillips, R. & Rix, M. (1989). Shrubs, Pan Books, London. Li, P. T. & Leeuwenberg, A. J. M. (1996). Loganiaceae, in Wu, Z. & Raven, P. (eds) Flora of China, Vol. 15. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, USA. online at www.efloras.org