History

Cross Made

UF/IFAS describes X-639 as a Cleopatra mandarin × Poncirus trifoliata hybrid developed in South Africa in the 1950s. The Parmak profile attributes an early-1950s cross to Dr. Hojby at CSFRI, but its parenthetical formula reverses the parent order. These are source-reported origin accounts; they do not resolve the direction of this specific cross or a more precise year.

• Dr. HojbyBreeder

  Parmak attributes an early-1950s Cleopatra mandarin × Poncirus trifoliata cross at CSFRI to Dr. Hojby. Its parenthetical formula reverses the parent order given by UF/IFAS, so this is a source-attributed maker account and does not resolve the specific cross direction.

Sources: ⁠[5]⁠[18]

Imported

UCR’s CRC 3957 profile reports that X-639 budwood was imported from South Africa in 1985 and lists PI 300256 / VI 469. This is the accession receipt, separate from the profile’s reported early-1950s development history.

• UC Riverside Citrus Experiment StationOther

  UCR’s CRC 3957 profile records the accession and reports budwood imported from South Africa in 1985.

Sources: ⁠[20]

Other

UF/IFAS states that X-639 was imported into Florida and first became available there in 1994. This profile does not date the earlier reported Riverside accession.

Sources: ⁠[5]