Forsythia europaea

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The closest relative of F. europaea is F. giraldiana, a species of Forsythia native to China.^[10] It was originally thought that a divergence between the two species occurred only half a million years ago, but more recent studies show that it is more likely that this happened between 2 and 10 million years ago.^[11] This is attributed to a significant shift in climate due to eurasian glaciation.^[12]

F. europaea was first cultivated in 1899, at Kew Gardens in London, United Kingdom.^[7] It is not as widely cultivated as other species of Forsythia as it is not as ornamental,^[6] although it is still occasionally grown in parks and gardens.^[6][13]

Cultivars produced by hybridisation of F. europaea with F. ovata, a more ornamental species of Forsythia native to Korea,^[14] include:

• Forsythia 'Meadowlark', which was developed at North Dakota State University.^[15] It produces deep-yellow flowers from its third year onwards,^[16] the buds of which are hardy to −35 °F (−37 °C).^[17] Its leaves are ivy-green.^[16]
• Forsythia 'Northern Sun', which was developed at the University of Minnesota.^[15] It grows 10 ft (3 m) tall and 8 ft (2.4 m) wide.^[18] Plants produce large, gold-coloured flowers,^[18] the buds of which are hardy to −30 °F (−34 °C).^[17]