Título en español

Seedlings of four varieties of citrus were used, representing four species with a range of cold-tolerance from high to very low. They were examined anatomically and the findings related to the accepted cold-tolerance of the varieties and with their performance in freezing tests. The varieties selected were, in descending order of cold-tolerance: 'Changsha' mandarin (Citrus reticulata); "Taiwanica' sour orange (C. taiwanica); 'Parson Brown' sweet orange (C. sinensis)', and 'Mexican' ('West Indian') lime (C. aurantifolia).