Flowers that want to be heard
Nectar-eating bats find their flowers based on echolocation. This works best with flowers that stick out show American and Colombia researchers in the New Phytologist.
Bats pollinated flowers have less showy colours, a wide bell forming corella. They smell musty. And the produce lots of pollen. In addition they often stick out from the rest of the plant.
For lots of these characteristics it is known by now how they benefit the bats and pollination. The wide flowers and lots of pollen enable the sticking of the pollen to specific regions of the bats head. The musty smell actually attracts the bats. And the flower colour explains itself. In the dark colours are less noticeable, so no reason for plants to invest energy in this at all.
But one question was still open: why are the bat pollinated flowers so well-exposed. This the researchers decided to investigate. Ther were three possible answers to this question: 1) in this way the wings of the bats are not hindered by the rest of the plant, 2) to avoid hidden predators a chance to attack unseen, or 3) in order that bats can better find the flowers.
Flowers with longer flowers stems can be heard better by bats
The researchers decided to test the later option. For this they placed flowers either alone i, or near a big plant in a big cage. In this way the researcher could test simple and complex situations. In the simple situations the researchers predicted that flowers would be better noticeable with echolocation than in complex situations. The last thing they tested was the effect of long or short flower stem length. The flower searching bats the researchers recorded on video.
The first thing the researchers noticed that in simple situations the bats found the flowers on short stems just as well as the flowers on long stems. In complex situations this was no longer the case. The bats took longer to find the flowers on short stems.
This shows that longer flower stems help the flower to be found by the bats. Or as the researchers say: it helps the flowers to be heard in the midst of the background noise of the rest of the plant.
Literature
Muchhala, N., Moreira-Hernández, J. and Zuluaga, A. (2024), Making yourself heard: why well-exposed flowers are an adaptation for bat pollination. New Phytol. https://doi.org/10.1111/nph.20075
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