Citrumelo (× ''Citroncirus'' spp.) is also called ''Swingle citrumelo trifoliate hybrid'', because it is

cold hardy Hardiness of plants describes their ability to survive adverse growing conditions. It is usually limited to discussions of climatic adversity. Thus a plant's ability to tolerate cold, heat, drought, flooding, or wind are typically considered measur ...

and is a hybrid between a 'Duncan' grapefruit and a

trifoliate orange The trifoliate orange, ''Citrus trifoliata'' or ''Poncirus trifoliata'', is a member of the family Rutaceae. Whether the trifoliate oranges should be considered to belong to their own genus, ''Poncirus'', or be included in the genus ''Citrus'' is ...

(''Poncirus trifoliata'' ( L.) Raf.), developed by

Walter Tennyson Swingle Walter Tennyson Swingle (January 8, 1871 – January 19, 1952) was an American agricultural botanist who contributed greatly to the classification and taxonomy of citrus. Biography Swingle was born in Canaan, Pennsylvania, and moved with his f ...

. Citrumelo is widely employed as a

citrus rootstock Citrus rootstock are plants used as rootstock for citrus plants. A rootstock plant must be compatible for scion grafting, and resistant to common threats, such as drought, frost, and common citrus diseases. Principal rootstocks Five types of rootst ...

, being resistant to the severe

citrus tristeza virus Citrus tristeza virus (CTV) is a viral species of the genus ''Closterovirus'' that causes the most economically damaging disease to its namesake plant genus, ''Citrus''. The disease has led to the death of millions of ''Citrus'' trees all over ...

and to phytophthora root rot as well as to

blight Blight refers to 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 organ ...

, cold, and

citrus nematode ''Tylenchulus semipenetrans'' (Citrus nematode, Citrus root nematode) is a species of plant pathogenic nematodes and the causal agent of slow decline of citrus. ''T. semipenetrans'' is found in most citrus production areas and diverse soil textu ...

. It produces yellow fruit which taste (if added sugar) and smell like an ordinary grapefruit. The trees are very hardy and can survive temperatures into the teens (

Fahrenheit The Fahrenheit scale () is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined his ...

Taxonomy

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

citrus ''Citrus'' is a genus of flowering plant, flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as Orange (fruit), oranges, Lemon, lemons, grapefruits, pomelos, and lim ...

, 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 Group epithets must conform to the ''Intern ...

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

References

External links

{{citrus Citrus Citrus hybrids