In my PhD interview, an (unofficial) question was asked of me; ‘What is your favourite plant?’ It’s a question I always struggle to find an answer for, partially because I’m chronically indecisive, but mainly because there are just too many exciting plants to choose from. I ended up blurting out that I liked Equisetum, because I had recently observed its spores. I did an impression. Of a spore. In an interview. (It worked, by the way).So what was it about impersonating the reproductive unit of a fern-relative that got me the job? Well, Equisetum plants produce spores that have four little arms, called ‘elators’. When the spores are in dry conditions, the little arms are unfurled, like the spore is asking for a hug. When, however, they encounter wet conditions, they curl right up. And no, it doesn’t happen so slowly that we can only see it with fancy sped-up film footage, it happens so fast that you can induce it just by huffing on the spores. As you can hear from this video, when I first observed this during a practical class I thought it was The Best Thing In The World. In fact, I still do.
Why do they do this? The science points to dispersal- it can help them get off the ground into the wind, or fall back to the ground, or get away from their spore-y brethren, but I reckon that really, they just like to dance.
If you’re interested, there’s a pretty cool paper written on the subject.