11 September, 2020


by Keigo Takahashi, Takao Itino

A queen of Bombus diversus visiting a flower
of Rhododendron japonicum.

Examination of the efficacy of pollinators that are not morphologically matched to a flower’s shape can deepen our understanding of the main pollinators of a plant species. In central Japan, Rhododendron japonicum is visited much more frequently by bumblebees than by butterflies although its flower shape is more suited for pollination by large butterflies. Here, we observed flower-visiting behaviour of Bombus diversus queens and the alpine black swallowtail butterfly, Papilio maackii, and compared their efficacy as pollinators. Papilio maackii always touched the stigma during a flower visit, whereas B. diversus queens did so for only 54% of their flower visits. As bumblebees visit neighboring flowers of a R. japonicum tree in sequence not like P. maackii, we hypothesized that they deliver self pollen to R. japonicum so that the fruit set would be low. However, the fruit set in a bumblebee-dominated area was 72.5%, significantly higher than that by hand-pollination with self pollen (31.4%). This suggests that R. japonicum can obtain sufficient fruit set by B. diversus queens although its flower shape morphologically matches to pollination by swallowtail butterflies.


Read the scientific publication in JPE.

Comparative floral ecology and breeding systems between sympatric populations of Nothoscordum bivalve and Allium stellatum (Amaryllidaceae)

 By Daniel Weiherer, Kayla Eckardt, Peter Bernhardt

A dense cluster of pollen tubes in Nothoscordum bivalve
paused at the entrance to the ovary

In the American midwest, prairie onion (Allium stellatum) blooms from late summer to early autumn while the closely related, false garlic (Nothoscordum bivalve) flowers in early spring. We compared the pollination and breeding systems of two extensive populations of both species within the same limestone glade at the Shaw Nature Reserve, Missouri (2018 and 2019).

 This required recording their respective flowering periods, individual floral life-spans, and pollinator attractants. 


Read the whole summary in: English!
Read the scientific publication in JPE.