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The three-year study on borage was conducted in Lublin, SE Poland. The aims were to investigate the flowering pattern and abundance, and the attractiveness (in terms of nectar and pollen production) for flower-visiting insects, mainly bees. Insect visitation and the effect of pollinators on fruit set and seed set were assessed as well. Flowering of borage started in the latter half of June and lasted eight weeks. The mean number of flowers · m−2 of the crop was 4570 per season. A borage flower produced on average 4.0 mg of nectar with a mean sugar concentration of 31.5%. The mean total sugar amount secreted in nectar was 1.2 mg. The pollen amount · flower−1 was 1.1 mg. A borage plant can supply insects with 1.1 g of nectar sugars and 1.1 g of pollen. The estimated nectar sugar yield and pollen yield per 1 m2 of the crop were similar, i.e. 5.2 g. Bees accounted for 73.0% of all insect visits to the borage flowers. The presence of insect pollinators increased the fruit set by 43.3% and seed set by 26.8%.

Offering more floral resources for urban bees can be achieved by growing ornamental bee plants. The aim of the present study was to evaluate selected Asteraceae (Calendula officinalis ‘Persimmon Beauty’ and ‘Santana’, Centaurea macrocephala, Cosmos sulphureus, Dahlia pinnata, Tagetes patula, Tithonia rotundifolia, and Zinnia elegans) as pollen sources for pollinators. Under urban conditions in Lublin, SE Poland, the investigated plants flowered from late June to the end of October. The mass of pollen produced in florets and capitula was found to be species-related. The highest pollen amounts per 10 florets (10.1 mg) as well as per capitulum (249.7 mg) were found for C. macrocephala. The mass of pollen yielded by a single plant depended on both the pollen mass delivered per disk florets and the proportion of disk florets in capitulum, and the flowering abundance of the plants. A single plant of D. pinnata and a single plant of T. rotundifolia each produced the largest pollen mass. Mean pollen yield per 1m2 of a plot ranged from 6.2 g (Z. elegans) to 60.7 g (D. pinnata). Pollen grains are tricolporate, with echinate exine, medium or small in size. They can be categorised as oblatespherical, spherical, and prolatespherical. The principal visitors to C. macrocephala, C. sulphureus, and C. officinalis were honey bees, whereas bumble bees dominated on T. rotundifolia and D. pinnata. A magnet plant for butterflies was Z. elegans. Among the investigated species, D. pinnata, C. macrocephala, and T. rotundifolia were found to be the most valuable sources of pollen flow for managed and wild bees.