Dichroa febrifuga (Hydrangeaceae) is an evergreen shrub with metallic blue fruit that persists throughout winter. Phylogenetic studies have indicated that D. febrifuga is closely related to Hydrangea macrophylla. The objective of this study was to produce hybrids between these two ornamental species. Reciprocal crosses were made between D. febrifuga and both diploid and triploid cultivars of H. macrophylla. Two-thirds of the seed capsules produced from these hybridizations were allowed to mature on the plant, after which time seed were collected and sown in a greenhouse. Embryo rescue was used with the remaining seed capsules. Ovules were excised from ovaries about 9 weeks after pollination and plated on Gamborg's B-5 media with 2% sucrose. Both germination techniques resulted in vigorous seedlings. Hybridity was verified in plants obtained from ovule culture using simple sequence repeat (SSR) markers. Reciprocal hybrids were obtained using both diploid and triploid forms of H. macrophylla. This study confirms the close relationship between D. febrifuga and H. macrophylla and provides valuable material for future breeding efforts.
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