In: Phyton, 50 Fasc. 2 (2011), S. 145-180 with 52 figures

Key words: Boraginaceae, Cerinthe minor, Onosma div. spec., Symphytum officinale, Symphytum tuberosum. – Anthesis, floral ecology, morphology, scatter-cone-blossoms, streukegel blossoms, pollen portioning, buzzing, vibratory pollen collection, nectar robbing, bite slits, concentrating nectar. – Andrena symphyti, Andrena lathyri, Andrena ovatula, Andrena similis, Andrenidae, Apoidea, Hymenoptera.

Summary

Symphytum, Onosma and Cerinthe bear streukegel blossoms with nectar. In Symphytum and Cerinthe a single anther needs 1–4 hours for opening. Pollen portioning results through successive ripening and opening within 1–3 days of the five anthers of a flower. In Onosma the anthers of a flower develop synchronously and an individual anther needs 1–3 days to be ripe and open along their whole length. In all the three genera, nectar secretion begins in the late bud stage.

Andrena (Euandrena) symphyti collects pollen in the three mentioned genera by manipulation of anthers and buzzing, nectar by robbing through transversal slits bitten near the base of the corolla-filament-tube. Nectar collection is interrupted by nectar concentrating. Members of Andrena subg. Taeniandrena (A. lathyri, A. ovatula, A. similis) split narrow floral tubes (calyx or corolla) longitudinally for nectar robbing. Other flower-visiting bees of Symphytum, Onosma and Cerinthe are also mentioned.