Frost Owari, Frost Satsuma, Silver Hill (sec. Cottin 2002); Silverhill Owari (sec. Hodgson 1967)
Citrus reticulata Blanco [Satsuma Group] (sensu Swingle and Reece 1967, Mabberley 1997); Citrus unshiu Marcov. (sensu Hodgson 1967; sensu Tanaka sec. Cottin 2002)
Hodgson (1967) noted that:
"Silverhill is a nucellar seedling selection of Owari from a cross made by W. T. Swingle of the U.S. Department of Agriculture in Florida about 1908. The variety was named and introduced about 1931. In collections in California, it is indistinguishable from the Frost Owari derived at the Citrus Research Center, Riverside, California, and almost certainly they are identical. They constitute what are considered to be the best clones currently available in the United States.
Silverhill has been tested in Japan, where the above characterization was taken to permit direct comparison with other varieties. It is recommended for planting in Japan as a promising, early shipping variety of Unshû."
Crown compact or dense, not weeping. First-year twig surface glabrous; second- or third-year twig surface striate; thorns absent or not persistent; prickles absent or not persistent. Petiole glabrous, length medium; wings narrow, adjoining the blade. Leaflets one, margin bluntly toothed, shade leaflet blades flat or weakly conduplicate, sun leaflet blades weakly or strongly conduplicate. Scent of crushed leaflets mandarin-like. Fruit as broad as long or longer than broad; rind yellow-orange (11), orange (12), or red-orange (13); rind texture slightly rough (4-5) or medium rough (6-7); firmness leathery; navel absent; flesh orange; taste acidic-sweet.
Hodgson (1967) provided the following additional notes on the cultivar:
"Fruit medium in size, slightly more oblate than most; rind relatively thin and smooth; seedless. Juice abundant; sugars high and acid low (hence very sweet); quality excellent; stores well. Season of maturity early (November).
Tree very vigorous (for satsuma), more upright than most others; productive; markedly cold-resistant."
Hodgson (1967) additionally noted that:
"Another nucellar selection, which so closely resembles Silverhill that it is virtually indistinguishable, is Tanikawa Unshû, which originated as a nucellar seedling in the breeding program of the Horticultural Research Station at Okitsu about 1920 and was named for its originator, T. Tanikawa. The only differences reported are a somewhat lower average sugar content in the fruit and slightly higher average yield to date. Like Silverhill, it is recommended as an early shipping variety."
Cottin, R. 2002. Citrus of the World: A citrus directory. Version 2.0. France: SRA INRA-CIRAD.
Hodgson, R.W. 1967. Horticultural varieties of Citrus. In: Reuther, W., H.J. Webber, and L.D. Batchelor (eds.). The Citrus industry, rev. University of California Press. http://lib.ucr.edu/agnic/webber/Vol1/Chapter4.html.
Mabberley, D.J. 1997. A classification for edible Citrus (Rutaceae). Telopea 7: 167–172.
Search for this cultivar in NCBI Entrez
Additional information on this cultivar at University of California: Riverside Citrus Variety Collection
Citrus ID Edition 2
October, 2011
idtools.org
