'USS Arizona' and 'USS California' Tropical Hibiscus (Hibiscus Rosa-Sinensis
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HORTSCIENCE 47(12):1819–1820. 2012. cultivars were discovered and selected by the inventors as flowering plants within the prog- eny of the stated cross-pollination in a con- ‘USS Arizona’ and ‘USS California’ trolled greenhouse environment at Poplarville, MS, in 2005. ‘USS Arizona’ and ‘USS Cal- Tropical Hibiscus (Hibiscus ifornia’ are intermediate between the two parents for most horticultural traits but rosa-sinensis L.) have improved flower color and garden performance (Fig. 1). Cecil T. Pounders1 and Hamidou Sakhanokho USDA-ARS, Thad Cochran Southern Horticultural Laboratory, P.O. Box Description 287, 810 Highway 26 West, Poplarville, MS 39470 ‘USS Arizona’ and ‘USS California’ were Additional index words. chinese hibiscus, Malvaceae, patio plant, ornamental breeding selected for use as accent plants for patios, pools, or other outside areas in climates with warm summers or as perennial flowering Tropical hibiscus (Hibiscus rosa-sinensis measured by seed set, some H. rosa-sinensis landscape shrubs in USDA hardiness zones L.), also commonly known as the shoe flower cultivars make better female parents, whereas 9 and 10. The cultivars were selected for their or chinese hibiscus, is a widely planted trop- others make superior male parents (Lawton, exceptional vibrant flowers, well-branched ical flowering shrub throughout the world. 2004). growth habit, and environmental tolerance This cultivated species is generally a highly Tropical hibiscus plants display great di- in hot, humid summers typical of the south- heterozygous polyploid of complex ancestry versity in flower color, size, and shape as well eastern United States, but should also exhibit (Singh and Khoshoo, 1970). At least 27 as plant habit. As compared with older hibis- good summer performance in areas of the chromosome numbers have been reported cus cultivars, modern tropical hibiscuses country with more moderate summers. for this species (Singh and Khoshoo, 1989) generally bloom more profusely, have more Plants of ‘USS Arizona’ are dense, making determination of the basic number diverse intense flower colors, and are cutting- upright-spreading with prolific production very difficult with a solitary report of 18 by propagated instead of grafted (Dickey, 1950; of uniform unique vibrant orange flowers Thombe (1959) being the lowest and widely Lawton, 2004). Breeders have traditionally (orange–red N30A) (Royal Horticultural So- accepted count. The Linnaean plant type had focused on developing cultivars adapted to ciety Flower Council of Holland, 2001) of red double flowers and was believed to be either of two basic market segments, florist moderate size (10 to 12 cm) with overlapping native to China where it was cultivated for its grade and landscape types. Florist-grade hi- petals (Fig. 2). Flowers on plants open for 2 d showy flowers (Kimbrough, 1997), although biscus cultivars are developed for the flower- and then old flowers abscise freely with no no wild forms of the species are known to ing pot plant market and generally need to be production of seed pods, even when polli- exist there. An alternate view is that the compact, responsive to growth regulators, nated. Foliage is medium green (green 133A) species is native to the south Indian Ocean have high bud counts under greenhouse pro- with mature leaves measuring 8 3 10 cm. islands with Madagascar as the center of duction environments, and have greener origin. This view is supported by the fact that denser foliage. Outdoor patio hibiscus culti- species from the region are genetically com- vars are developed for the landscape trade patible with H. rosa-sinensis and that the and can be planted in the ground in warmer Polynesian migration parallels the distribu- climates such as Florida or California or used tion of the species to China and eventually as summer potted accents on patios and throughout the entire Pacific region. Species around pools. Faster growth to fill larger pots, indigenous to the region thought to play a major climatic tolerance, and extended bloom cycle role in the development of the modern H. rosa- are traits valued in this group (Lawton, 2004). sinensis of commerce include the south Indian Both ‘USS Arizona’ and ‘USS California’ Ocean island species H. schizopetalus Hook., were selected for the outdoor patio market. H. liliiflorus Cav., H. fragilis DC., and H. boryanus Hook and Arn. in combination with Origin the Pacific Island species H. kokio Hillebrand, H. arnottianus Gray, H. wimeae Heller, H. The two new tropical hibiscus cultivars denisonii auct., and H. storckii Seeman (Singh are products from a planned hibiscus breed- and Khoshoo, 1989). ing program conducted by the inventors at Fig. 1. Comparison of flowers from parents ‘Car- Seed set in H. rosa-sinensis is extremely Poplarville, MS. The objective of the re- oline’ (left) and ‘Cherie’ (right) to progeny rare under normal conditions in the tropics search is to create new, well-branched hibis- ‘USS Arizona’ (top center) and ‘USS Califor- (Sharma and Sharma, 1962), but the species cus cultivars with attractive flower colors nia’ (bottom center). has moderately high pollen fertility of 60% in combination with other desirable horticul- (Singh and Khoshoo, 1989). Research in Italy tural traits including dense crowns appropriate verified that setting seed on H. rosa-sinensis for larger containers or landscape deployment, can be very difficult but can be improved early and uniform flowering over an extended with proper attention to environmental con- bloom cycle, and good garden performance ditions during pollination. Highest seed set during hot, humid summers. was achieved in the spring and fall in mod- Both cultivars originated from a cross- erate shade when the temperature ranged pollination of H. rosa-sinensis ‘Caroline’ from 16 to 27 °C and dew point was between (PP11,779) as the female, or seed, parent 10 and 16 °C (Mercuri et al., 2009). As and H. rosa-sinensis ‘Cherie’ as the male, or pollen, parent. ‘Caroline’ is characterized by glossy foliage, dense symmetrical plant habit Received for publication 27 Sept. 2012. Accepted and numerous orange flowers. ‘Cherie’ is for publication 23 Oct. 2012. marketed extensively as a flowering pot plant 1To whom reprint requests should be addressed; as a result of outstanding production traits e-mail [email protected]. and prolific yellow–orange flowers. The new Fig. 2. Typical flower of ‘USS Arizona’. HORTSCIENCE VOL. 47(12) DECEMBER 2012 1819 Under commercial production conditions, generations. The response of the clones to plants develop rapidly in containers and dis- growth regulators has not been researched. play good tolerance to common pests. Ulti- mate plant size is dependent on container size Availability and environmental conditions with plants in a No. #3 nursery pot growing to 1.0 m high 3 Additional information or a list of nurs- 0.5 m wide within six months under optimum eries propagating ‘USS Arizona’ and ‘USS conditions. Under tropical landscape condi- California’ is available on written request to tions, plants should mature to 3mhigh 3 Cecil Pounders; USDA-ARS (e-mail: Cecil. 1.5 m wide. [email protected]). The USDA-ARS Plants of ‘USS California’ are semicom- does not have plants for sale. In addition, pact with an upright spreading growth habit specimens of the releases have been depos- with prolific production of yellow (yellow ited in the National Plant Germplasm System 12B) flowers of moderate size (11.5 to Fig. 3. Typical flower of ‘USS California’. where they will be available for research 13.5 cm) with a small white, then red swath purposes. It is requested that appropriate of color at the base of each petal, which is recognition be made if this germplasm con- perceived as a small red eye in the flower on decks, patios, and pool areas where the tributes to the development of other new (Fig. 3). Pronounced white veins in the petals plant form and rich flower colors can be cultivars. give flowers a textured appearance. Flowers appreciated. In cooler climates, plants used open for 2 d and then fall from the plants. No outdoors should be placed in warm locations Literature Cited production of seed pods has been observed, sheltered from cool winds. The cultivars may even after hand pollination. Foliage is dull also be used as woody perennial plants in Dickey, R.D. 1950. Hibiscus in Florida. University green (green 138B) with leaves measuring landscapes as hedges, specimen plants, and of Florida Agricultural Experiment Station 7 3 9 cm. Growth and foliage color is corner plants in tropical climates in USDA Bulletin 467. Gainesville, FL. more stable than many other yellow-flowered hardiness zones 9 and above. Plants should be Dole, J. and H. Wilkins. 1999. Floriculture: Prin- ciples and species. Prentice Hall, Upper Saddle H. rosa-sinensis cultivars. During nursery grown in full sun but respond to afternoon River, NJ. production, plants develop rapidly in con- shade in regions with intense summer sun. Kimbrough, W.D. 1997. Hibiscus. In: Encyclopedia tainers and display good tolerance to com- Other cultural practices for maximum flower- Americana. Grolier, Inc., Danbury, CT. p. 174. mon pests. Maximum plant size is dependent ing and plant development conform to estab- Lawton, B.P. 2004. Hibiscus—Hardy and tropical on container size and climatic conditions. lished practices for H. rosa-sinense clones. plants for the garden. Timber Press, Inc., Port- Plants grown in a No. #3 nursery pot were No unusual insect or disease pests have been land, OR. 0.8 m high 3 0.4 m wide within six months observed on plants growing in Poplarville, Mercuri, A., L. Braglia, L. De Benedetti, M. under optimum production conditions. Under MS, and Sarasota, FL, but strict pest man- Ballardini, F. Nicoletti, and C. Bianchini. tropical landscape conditions plants, should agement programs are required during pro- 2009. New genotypes of Hibiscus 3 rosa- sinensis through classical breeding and genetic mature to 2.5 m high 3 1.5 m wide.