A Banquet of Goldenrod at Lathrop

by Barbara Walvoord

Originally publish in Lathrop Lamp Post August 10, 2017

We have banquets for humans at Lathrop–the 4th of July picnic, the lobster feast, the Thanksgiving day meal.  But we also have banquets for our non-human residents.  Right now, goldenrod is on the menu.  The most numerous native wild flower in Lathrop east campus meadows, goldenrod is turning our land into a rich yellow banquet for our wild residents.

ACHOO! you may be saying.  However, goldenrod is not the culprit; instead, it’s ragweed, which blooms at the same time. Resident Alice Richardson, a landscape architect who knows a TON about native plants, explained the general rule to me in an e-mail: “As a general rule, most pollen allergens are produced by visually insignificant flowers which are typically wind pollinated – e.g. some trees, most grasses, ragweed.  Showy flowers have evolved to attract pollinators to physically carry pollen to other flowers, thus enabling cross pollination and ensuring genetic robustness.  Ergo – if it is a pretty flower, it is unlikely to cause allergies unless ragweed (or other) pollen has landed on the plant and causes one to sneeze when making a bouquet of goldenrod.”

So goldenrod has heavy pollen that needs pollinators, not wind.  Those showy flowers send a message to pollinators:  we have delicious nectar and pollen for you–come over here and eat!

At Lathrop, we used to mow our meadows in July, cutting down the banquet just as it was providing the food our wildlife needed to prepare for migration or winter survival.  But now we hold off on our meadow mowing until late October, so our meadows can continue to provide richly for our wildlife.  Goldenrod pollen and nectar nourish many butterflies, wasps, and bees.  Goldenrod leaves and stems feed the larvae (caterpillars) of 112 species of Lepidoptera (butterflies and moths), who are notoriously picky eaters.  Sometimes the invasion of larvae on the stem causes the plant to form a bulbous tissue mass called a gall, around the larvae.  Then the larvae eat the gall.  Woodpeckers may peck open the galls and eat the insects in the center. Wasps may also penetrate the galls with their ovipositor and lay eggs in the larvae.  Whatever larvae can escape all this may become a protein-rich meal for our birds. Meanwhile, our thick meadow grasses and wildflowers shelter voles and mice, which feed our hawks, snakes, owls, foxes, and coyotes. It’s one big feeding frenzy out there, and the goldenrod, waving in the breeze, is a big sign saying, “Dinner is served.”

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