Citrumelo (× ''Citroncirus'' spp.) is also called ''Swingle citrumelo trifoliate hybrid'', because it is cold hardy and is a hybrid between a 'Duncan' grapefruit and a trifoliate orange (''Poncirus trifoliata'' ( L.) Raf.), developed by Walter Tennyson Swingle. Citrumelo is widely employed as a citrus rootstock, being resistant to the severe citrus tristeza virus and to phytophthora root rot as well as to

blight Blight is a specific symptom affecting plants in response to infection by a pathogenic organism. Description Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. A ...

, cold, and citrus nematode.Swingle citrumelo trifoliate hybrid (CRC 3771)
at Citrus Variety Collection The trees can survive temperatures into the teens (

Fahrenheit The Fahrenheit scale () is a scale of temperature, temperature scale based on one proposed in 1724 by the German-Polish physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accou ...

); one specimen in

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

reportedly survived temperatures below zero Fahrenheit. The fruit are yellow, and up to 4 inches across in size. Their taste is described as "like a cross between a lemon and a grapefruit", or "if sprinkled with sugar henlike an ordinary grapefruit, harvested perhaps a bit too early".

Taxonomy

Trifoliate orange, according to Swingle, belongs to a citrus-related genus called ''Poncirus'', while grapefruit equivocally belongs to the genus

citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...

, hence the

botanical name A botanical name is a formal scientific name conforming to the ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) and, if it concerns a plant cultigen, the additional cultivar or cultivar group, Group epithets must conform t ...

× ''citroncirus'' is a hybrid genus, derived from citrus and poncirus.

References

External links

{{citrus Citrus Citrus hybrids