Friday, 31 January 2014

Almonds, vanilla or rat poison?

The other week, I was writing about ladies'-tresses orchids in Scotland. Then another one popped up in East Ontario. Well, as a true orchidmaniac, I was intrigued.

It seems these orchids are hard to distinguish - apart from one key feature. Their fragrance.

Spiranthes cernua and Spiranthes magnicamporum are so similar in appearance that even expert taxonomists have difficulty telling them apart.

Here's something that caught my eye. Just over 30 years ago, S. magnicamporum didn’t even technically exist as a species, according to a delightful article in a Chicago wildflower magazine.

However, there are small clues. S. cernua usually begins to bloom in mid-August, while magnicamporum flowers slightly later, in early to middle September. Cernua usually still has its leaves by the time it flowers, while magnicamporum loses all its leaves. Cernua prefers wetter habitats than magnicamporum, and is self-pollinated instead of pollinated by bees like magnicamporum.

But what's an amateur to do? Use your nose.

If there are enough of them, you can smell the scent out on the prairie,” says Cathy Bloome, an appropriately-named orchid monitor in Lake and Cook Counties. She describes the scent as similar to vanilla. Others have described it as smelling like almonds.

Some can detect the compound likely responsible for the scent: it's coumarin, a nature-derived flavouring used in food until the 1950s and more recently as a somewhat controversial scent in tobacco and perfume. It was found to cause liver damage, and now also serves as a component in rat poison.

Well, that's something I didn't know.

By Pamela Kelt

Captions: Spiranthes cernua and Spiranthes magnicamporum. Can you tell which is which?