Duncan Grapefruit

Duncan is an old white-fleshed, seedy Florida grapefruit. Hodgson (1967) reports that the seedling from which Duncan originated was planted near Safety Harbor around 1830; he attributes its seed to a tree from Count Odette Philippe’s original planting. He states that Duncan was introduced about 1892 by A. L. Duncan of nearby Dunedin and named for him. These are attributed historical accounts; exact parentage, planter, and formal selector or namer are not established.^{⁠[4]⁠[2]⁠[3]}

UCR’s CRC 3832 collection description reports smooth, pale-yellow fruit with a medium-thick rind and very pale-yellow, juicy, seedy flesh; it records a January–May season at Riverside and describes a large, spreading, vigorous tree. These are collection-level descriptions from Riverside and do not establish the same season or tree performance elsewhere. Hodgson also records a reputation for cold resistance without measured exposure data.^⁠[1]⁠[4]

The 2007 karyotype study used CMA/DAPI staining and rDNA-FISH. Its abstract reports Duncan Grapefruit in a marker group with two C-type and six D-type CMA-positive marker chromosomes and four 45S rDNA sites; it also reports two 5S rDNA-bearing chromosomes in each accession examined. These marker patterns are not a ploidy determination, full chromosome count, shared cultivar identity or proof of parentage.^⁠[14]