Leaf and Stem Cold Hardiness of 17 Broadleaf Evergreen Taxa

Abstract

Abstract The leaves and stems of 17 broadleaf evergreen taxa were screened for cold hardiness in laboratory tests. Leaves of Ilex were generally less cold hardy than stems. However, the leaves of I. × koehneana ‘Wirt L. Winn’, Ilex latifolia and Ilex ‘Lydia Morris’ were equal to or more cold hardy than the stems. Maximum cold hardiness of most taxa occurred in mid-January. Ilex opaca, Ilex opaca, ‘Greenleaf’, and Ilex × attenuata ‘Foster's #2,’ were the most cold hardy. Among the Ilex × attenuata cultivars, ‘Foster's #2’ was more cold tolerant than ‘Savannah’ and ‘East Palatka.’ Ilex latifolia and Ilex ‘Lydia Morris’ were least cold hardy. I. ‘Nellie Stevens’ and I. × koehneana ‘Wirt L. Winn’ were intermediate. Osmanthus heterophyllus ‘Gulftide’ was the hardiest tea-olive, followed by Osmanthus americanus, Osmanthus × fortunei and Osmanthus heterophyllus ‘Rotundifolius’. Prunus laurocerasus ‘Zabeliana’ was hardier than ‘Schipkaensis’ than ‘Otto Luyken’. The actual differences, however, were slight.