Sunday, July 3, 2011

Mountain laurels instead of rose bushes?

Last year I was traveling along the Blue Ridge in May and was pleasantly surprised by the beauty of the blooming mountain laurels. I had to look again and again to convince myself that what I was looking at wasn’t a rose garden but just a natural grove of mountain laurels.

I want that look in my garden. I have two rose bushes which I inherited from the previous owner of the property and I want to replace them. The advantages are obvious to me. Roses are not native; they provide no food for pollinators. Mountain laurel, on the other hand, is pollinated primarily by native bumble bees.
It has a peculiar system of pollination. The unopened blossoms present little knobs which give them a funny look. When the flowers open, the function of these little knobs become apparent. They are pockets that hold the anthers (the pollen carrying part of the flower) trapped. It still doesn’t explain why this is so; in most flowers the anthers are free and exposed, better to spread their pollen at the slightest touch of a flower visitor.

The mountain laurel has a different strategy. The pollen is well protected against rain and wind; but when a pollinator lands on the flower searching for nectar, the weight acts as a trigger, causing the taut stem of the anther to spring. The anther hits the pollinator gently on the back and gives it a dusting of pollen.
Mountain laurel flowers produce a moderate amount of pollen; but most of it ends up where it is intended, on the body of a pollinator, rather than being wasted in other ways. It seems like a highly economic method to spread the pollen.

List of articles