Still Green at Lathrop

by Barbara Walvoord

If you walk through our woods at either campus this time of year, you may spot mountain laurel (Kalmia latifolia), still sporting its shiny, oblong green leaves among the brown, bare branches of our oaks and maples. I took this photo on January 12, 2016, at the far west end of Mulberry Meadow, near Bassett Brook, which you can see in the background, with its border of snow.

Mountain laurel’s beautiful flowers have an unusual way of dispersing their pollen. Many other flowers lift their stamens, covered with pollen, and passively wait for an insect to crawl around on them, hoping the pollen will stick to the insect’s body. But our mountain laurel shoots its pollen onto the insect. As the flower grows, the filaments of its stamens are bent and brought into tension. When an insect lands on the flower, the tension is released, catapulting the pollen forcefully onto the insect.

This unusual trait was studied by–a retiree! Physicist Lyman Briggs, after his retirement from the National Bureau of Standards, became fascinated with how mountain laurel catapults its pollen, so he conducted a series of experiments to explain it. He found that a flower can fling its pollen up to 6 inches.

Mountain laurel is also known as spoonwood, because people used to make spoons from its strong, close-grained wood.

Mountain laurel is host to 31 species of native lepidoptera (butterflies and moths) as well as other insects, which then feed our birds and other animals. Alien invasives such as multiflora rose and bush honeysuckle support many fewer native insects (http://udel.edu/~dtallamy/host/).

Fifty acres of our Lathrop forests, on both campuses, are now nearly free of invasive shrubs and vines, so our mountain laurel, with its resilient evergreen leaves, its strong wood, and its phenomenal propagating projectiles, can continue to be studied, and enjoyed, by retirees like us.

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