As promised in last week’s Weedy Weekday post, today’s subject is myrmecochory, otherwise known as seed dispersal by ants.
The use of ants in dispersing seeds is a relatively common phenomenon, despite not being something that is as widely acknowledged as, say, wind dispersal. (Wind dispersal is referred to as ‘anemochory’, if you’re interested). Most plants that do utilise ants in this way produce seed that have eliasomes. These are appendages attached to their seeds which are particularly appealing to ants. The ants carry the seeds back to their nest, eat the eliasome and discard the seeds on the midden (rubbish pile). As a result, the parent plant has managed to get their seeds carried off to new and exciting territories. On top of this, the seeds are given an ideal seed bed in which to cultivate their new existence. The ants are fed, the parent plant’s happy, and the seed has taken up residence in a desirable and trendy new neighbourhood. Everyone’s happy!
Myrmecochory is particularly relevant to this blog as it occurs pretty widely across many plants in the Fumariaceae family (technically a subfamily). I was looking through last year’s photos and remembered my photographic battle with an ant involved in the act of myrmecochory. Let’s call him Alan. It is surprisingly difficult to take photos of ants (for someone of my skill levels anyway), and Alan was a particularly sprightly fellow. I think ants usually pick the seeds up from the ground, once they have fallen from the plant. Alan had gone right to the source and climbed into a ripening seed pod. He then proceeded to wander round holding a seed and trying to get out. He struggled. It took him so long I go bored and went away.
Seeing as the above picture doesn’t show the seeds, and the attached eliasomes, too well, here’s a photo of some Corydalis vittae seeds which shows them in a much clearer light.
I mentioned in the Weedy Weekday post that both featured plants employ myrmecochory. Pseudofumaria lutea (Yellow Corydalis), being part of Fumariaceae produces seeds with eliasomes. Cyclamen have seeds with a sticky coating, instead of having eliasomes. If you’ve ever handled fresh Cyclamen seeds, their stickiness soon becomes apparent. It’s a slightly different mechanism, but the end result is the same. Clever plants.
So ends our adventure into the world of myrmecochory. I hope you enjoyed it. It is only one of a number of myrmecophytic interactions that have arisen between plants and ants. Whilst many of these mutualistic relationships take place in far flung places across the globe, mymecochory is something we can observe in our own gardens. Don’t forget to subscribe for other scintillating tit-bits of botanical irrelevance!