A Curious Case of Gerbil Pollination

The hedgehog lily a.k.a. Massonia depressa hails from arid regions of South Africa. As with most plants from this region, it is highly adapted to its semi-desert environment. Its bizarre yet beautiful appearance belies something peculiar - a pollination syndrome that may surprise you. The hedgehog lily is pollinated by desert rodents such as gerbils.

Let's back up a second though. The genus Massonia has a certain level of confusion hanging around. For starters, despite its common name, it is not a lily at all. It was originally placed in the family Hyacinthaceae but now resides in the family Asparagaceae.

During the hot summer months this plant goes dormant, retreating underground in the form of a bulb. Come winter, two broad leaves are produced that lay flat on the ground. The positioning of the leaves in such a way may serve a few different purposes for the hedgehog lily. For starters, leaves laying flat on the ground may help the plant avoid herbivory. It may also help reduce water loss from both the underside of the leaves as well as from the soil surrounding its roots. Finally, it may also play a role in temperature regulation. Many different plant families in this region seem to have converged on a similar strategy.

Now let's get back to the flowers. Winter is also the flowering season. A stunning inflorescence is borne between the leaves. The cream colored flowers lay flush with the ground and are quite stiff. What is most peculiar about these blooms is that they emit a yeasty odor. All of these are adaptations for attracting its pollinators - rodents.

A study published in 2001 showed that when rodents were excluded from the flowers, seed set was highly reduced. Throughout the study, the authors noted four different species of rodents visiting the flowers at night. Two of these rodents were gerbils. Another adaptation for rodent pollination, albeit a subtle one, is extremely viscous nectar. The nectar of the hedgehog lily is 400 times as viscous as other nectar solutions with a similar sugar content.

This allows the rodents to effectively lap up the nectar, thus enticing them to visit the flowers more often. The authors also found that these rodents are often covered in hedgehog lily pollen throughout the blooming season. It coats their fur and makes up a large portion of their feces. Though this is not the only species to utilize rodents as pollinators, this is nonetheless a rare pollination syndrome.

Photo Credits: Graham Duncan, Kirstenbosch Botanical Garden and Steven D. Johnson, Anton Pauw, and Jeremy Midgley

Further Reading:
http://www.amjbot.org/content/88/10/1768.full

http://www.kew.org/science-conservation/plants-fungi/massonia-depressa-hedgehog-lily