Saturday, July 4th, 2009
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STREET ADDRESS Polk County Corner Gibson St and Ward St 60 Gibson Street Columbus, NC 28722 (828) 894-8218 Phone (828) 894-5693 Fax Map & Mailing Information 
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Re-inventing Sweetshrubs at MHC 'Venus' Sweetshrub HybridPlant breeders at NC State University have been busy re-inventing our native sweetshrub. Dr Tom Ranney, Professor of Horticulture at the Mountain Horticultural Crops Research Station near Fletcher, NC, has created a new form of sweetshrub for gardeners to enjoy. His new hybrid borrows genetic material from three different species of Calycanthus, the Carolina Sweetshrub, the California Sweetshrub and the Chinese Wax Shrub. Background The Carolina Sweetshrub (Calycanthus floridus) is naturally found throughout much of the eastern United States. It commonly grows as an understory shrub in mixed deciduous forests, often along streams and in moist woodlands. Height can vary and ranges from 3 to 9 feet, growing as multi-stemmed shrubs with suckering shoots arising from the base and roots. The leaves and stems are strongly aromatic, while the flowers, are the main attraction. Sweetshrub flowers are primitive upright flowers that are normally reddish-brown in color. Some specimen plants have strong fragrance while other plants have little to no scent. Most plantsmen say the flower scent reminds them of ripe melons with subtle accents of cinnamon and spices. The California Sweetshrub (Calycanthus occidentalis ) is naturally found in Washington state and California as an understory species along streams and on moist canyon slopes. Although similar to the Carolina Sweetshrub, the California species is much larger plant growing to over 12 feet in height. In addition the flowers are also larger, a brighter red color but typically not as fragrant. The Chinese Wax Shrub (Calycanthus chinensis ) is a rare plant species native to the Zheijang Province in southeast China. This shrub was only recently introduced into cultivation. It is a medium-sized shrub, ranging in height from 3 to 9 feet with large glossy leaves. Unlike our North American Sweetshrubs, the flowers on the Wax Shrub open more completely and are multicolored with the outer petals being whitish-pink and the inner petals being a strong yellow with occasional purple streaks at the base of the petals. Unfortunately there is little fragrance with this Chinese species. Despite its fairly southern origins in China, the Wax Shrub has proven hardy into Climate Zone 5. The Break Through In 1991 an undergraduate student in Horticultural Science at NC State University by the name of Richard Hartlage, performed a reciprocal cross between the Chinese Wax Shrub (Sinocalycanthus chinensis) and our native Carolina Sweetshrub (Calycanthus floridus). Four seedlings resulted from this cross, one of which appeared to be a hybrid and flowered 5 years later. In many aspects, this new hybrid combined the best qualities of both parents with large, maroon, wine-red flowers that opened widely with a subtle fragrance. This hybrid was very floriferous and now is named 'Hartlage Wine' Sweetshrub. There has been a fair amount of confusion about the taxonomy of the Chinese Wax Shrub. At first it was thought that the correct classification was Sinocalycanthus chinensis. However, recent molecular data indicates that the Chinese Wax Shrub is more accurately suited for the genus Calycanthus. It is not uncommon to find other closely related plants in both Asia and North America. Today we consider the Wax Shrub to be Calycanthus chinensis. Results of Controlled Crosses Encouraged and inspired by the success of the 'Hartlage Wine' Sweetshrub, Dr Tom Ranney has been working at the Mountain Horticultural Crops Research Station to continue to develop new hybrids of Calycanthus. NC State plant breeders have successfully created additional hybrids between the Chinese Wax Shrub and the Carolina Sweetshrub and new hybrids between the Chinese Wax Shrub and the California Sweetshrub. Although most of these new hybrids are extremely infertile, Dr Ranney and other researchers have been able to produce a limited number of advanced generation hybrids that include genes from all three Calycanthus species. The potential for these new plants for the nursery industry and gardeners is outstanding. Introducing 'Venus' Sweetshrub  One of the outcomes of the plant breeding work is a recent release called 'Venus' Sweetshrub. This new sweetshrub is a complex hybrid, developed at the MHC Research Station near Fletcher, NC. It has the Chinese Wax Shrub (C. chinensis) Carolina Sweetshrub (C. floridus) and California Sweetshrub (C. occidentalis) in its pedigree. The result is an exceptional plant with great vigor and numerous flower buds. This medium sized shrub has medium green colored leaves that are typically larger than our native sweetshrub foliage. What is striking about 'Venus' is its large, ivory-yellow buds that open into 3 to 4 inch white flowers that resemble water lillies. The flowers have an interesting fragrance with the fruity aroma of ripe melons. Flowering is primarily in Spring, though sporatic flowers are produced throughout the growing season. Although the sweetshrubs are not generally considered mainstream landscape plants, new hybrids like 'Venus' show great promise. Currently the native Carolina Sweetshrub is used as a landscape plant in a shrub border or as shrub for natural areas. It is believed that these new Calycanthus hybrids will become increasingly popular and broaden the appeal of this worthy plant. 'Venus' Sweetshrub received a plant patent in August 2005. It is currently being produced in nurseries in South and North Carolina. It is anticipated that the new Calycanthus hybrids will be cold hardy to Climate Zones 6, 7 and 8. Photographs courtesy of Dr Tom Ranney, Mountain Horticultural Crops Research Station, Fletcher, NC. For more information contact Dr Ranney at Tom_Ranney@ncsu.edu . |