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Citrus ID






Hiryiô, Hiryu, Monstrosa (sec. Cottin 2002)

Cultivar or taxon


Citrus trifoliata L. (sensu Mabberley 2004, Bayer et al. 2009); Poncirus trifoliata (L.) Raf. var. monstrosa (T. Ito) Swingle (sec. Swingle and Reece 1967); Poncirus trifoliata (L.) Raf. (sensu Tanaka sec. Cottin 2002)



Hodgson (1967) notes that: "According to Swingle [and Reece] ([1967]), the most important and interesting [among dwarfed ornamental trifoliate varieties] is the Japanese hiryo or Flying Dragon variety, which he introduced to the United States in 1915....It is a curious monstrosity which he has accepted—unnecessarily, in the opinion of the writer—as the botanical variety monstrosa of T. Ito.



Crown compact or dense, not weeping. First-year twig surface glabrous; second- or third-year twig surface striate; thorns recurved; prickles absent or not persistent. Petiole glabrous, length medium or very long; wings narrow or medium, adjoining the blade. Leaflets three, margin bluntly toothed or serrate/serrulate, rachis wings absent, shade leaflet blades flat, sun leaflet blades flat or weakly conduplicate. Leaflets have no scent when crushed. Fruit broader than long; 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 or green/greenish; taste sour.

Hodgson (1967) provided the following additional notes on this cultivar: "Grown primarily as a potted plant, this is a highly dwarfed variety with very small leaves, the leaflets of which are commonly reduced to linear filaments, and slender crooked branches armed with large, downward-curved spines."

Swingle and Reece (1967) provided the following additional notes on the cultivar: "Tokutaro Ito's original diagnosis in English reads as follows: "Citrus trifoliata var. monstrosa T. Ito, nov. var. Branches and spines crooked and curved, leaves very slender." A very dwarf variety, with tortuous slender branches with curved spines; the leaves are very small with the leaflets often reduced to linear filaments on which the oil glands appear as node-like thickenings."



Swingle and Reece (1967) additionally noted that: "In Japan this curious monstrosity, called hiryô, or flying dragon, is esteemed for culture as a dwarf potted plant."



Bayer, R.J., D.J. Mabberley, C. Morton, C.H. Miller, I.K. Sharma, B.E. Pfeil, S. Rich, R. Hitchcock, and S. Sykes. 2009. A molecular phylogeny of the orange subfamily (Rutaceae: Aurantioideae) using nine cpDNA sequences. American Journal of Botany 96: 668–685.

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.

Mabberley, D.J. 2004. Citrus (Rutaceae): A review of recent advances in etymology, systematics and medical applications. Blumea 49: 481–498.

Swingle, W.T. and P.C. Reece. 1967. The botany of Citrus and its wild relatives. In: Reuther, W., H.J. Webber, and L.D. Batchelor (eds.). The Citrus industry. Ed. 2. Vol. I. University of California, Riverside.



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Citrus ID Edition 2
October, 2011