Nectar and pollen production in ornamental cultivars of Prunus serrulata (Rosaceae)

Planting ornamental species can help to create pollinator-friendly habitats. In the present study the flowering phenology and floral reward (nectar and pollen) in two cultivars of Prunus serrulata (‘Kanzan’ and ‘Amanogawa’) were evaluated in 2014-2015 in the city of Lublin (south-east Poland). On average, the onset of flowering of P. serrulata occurred in the first ten days of April (‘Kanzan’) or at the end of April (‘Amanogawa’), and lasted 8-17 days. In each year of the study, P. serrulata ‘Kanzan’ started flowering 11-18 days earlier than P. serrulata ‘Amanogawa’. The double flowers of P. serrulata ‘Kanzan’ offered only tiny amounts of nectar and pollen. The total mass of sugars was 0.59 mg per flower and that of pollen 0.08 mg per flower. The semi-double flowers of P. serrulata ‘Amanogawa’ produced 4.5 mg of sugars per flower and 0.17 mg of pollen per flower. The frequency of pollinator visits to flowers was low in P. serrulata ‘Amanogawa’ and very low in P. serrulata ‘Kanzan’. Therefore, if pollinator-friendly arrangements are made in urban areas, these cultivars should not be planted.