Characteristics of blooming, pollen production, and insect visitors of Polemonium caeruleum L. – a species with a potential to enrich pollinator-friendly urban habitats

Abstract

Mosaic structure of urban green areas is regarded as favorable for pollinating insects. Ornamental plants can provide food resources to pollinators and may thus be used to create pollinator-friendly habitats. However, detailed data on forage quantity and quality is required for the selection of the most valuable plant species. In this paper, blooming biology, pollen production, and insect visitors of two forms (blue-flower and white-flower) of Polemonium caeruleum were studied in the period of 2012–2014 in Lublin, SE Poland. Both forms bloomed from mid-May until mid-June. The average mass of pollen produced in a single flower was 1.57 mg and 1.39 mg in blue-flower and white-flower forms, respectively. On average, the blue-flower form produced 7.74 g of pollen/m2, while the white-flower form yielded 6.54 g of pollen/m2. Both forms attracted mainly honey bees and solitary bees. Polemonium caeruleum can be considered a good source of pollen for honey bees and wild insect pollinators and should be propagated in urban pollinator-friendly arrangements.

Keywords

• blooming
• ornamental plants
• pollen production
• forage flora
• insect visitors
• honey bee
• solitary bees