Wind and Sagebrush

By late summer, most of Utah’s flowering plants have fizzled out for the year—those that remain are looking pretty spent. But not true for the sagebrush. It’s show time for over 20 types of sagebrush of the Intermountain West.

Like grasses and conifers, sagebrush plants are pollinated by the wind. They have no need for the specialized traits designed to attract live pollinators. Instead, they have evolved other strategies to survive and multiply.

For instance, wind-pollinated plants don’t need showy, colorful petals to attract insects or birds. The wind is going to do its job anyway regardless of visual cues. Thus sagebrush flowers are very small and nondescript. In fact, when passing by flowering sagebrush you might not even notice that it’s in bloom. Look for long spikes with clusters of tiny flower heads. The pale yellow flowers are concealed by petal-like bracts, which are the very same color as the rest of the plant.

While the flowers of sagebrush lack in beauty, they make up in quantity. A single flowering stem of the most common sagebrush—known simply as big sagebrush–can hold hundreds of flower heads that produce a massive amount of pollen. Most wind-blown pollen grains won’t end up anywhere near the female part of another plant. So to make up for this risky method of fertilization, individual plants must produce greater volumes of pollen. In contrast, plants with live pollinators get door to door service during fertilization. Far less pollen is needed to get the same job done.

Scent is another way for plants to attract live pollinators. Species pollinated by bees and flies have sweet scents, whereas those pollinated by beetles have strong musty, spicy, or fruity odors. However, the iconic western scent of the sagebrush has absolutely nothing to do with pollination. Instead, the pungent aroma of the sagebrush is a by-product of certain chemicals produced in the leaves. These chemicals evolved to repel animals and to reduce the odds of being eaten or grazed.

The chemicals—bitter terpenes, camphors and other secondary compounds–—peak in early spring. But as the late-summer flowering period approaches, the chemicals start to break down. By winter, browsers like deer and elk can nibble on the protein-rich seed heads without getting a nasty aftertaste.

Thanks to botanist Leila Shultz for sharing her knowledge of sagebrush. For a link to the online version of Leila’s book Pocket Guide to Sagebrush, go to www.wildaboututah.org
If you’d like a hard copy of this Pocket Guide, send an email to wildaboututah@gmail.com We have 5 copies to give away to listeners from across the state.

For Wild About Utah and the Quinney College of Natural Resources, I’m Holly Strand.

NOTE: The copies are gone. You can view the book as a .pdf here or check here for the next printing from https://www.sagestep.org/pubs/brushguide.html.

Credits:

Photo Courtesy & Copyright 2007 Dr. Leila Shultz
Text: Holly Strand, Quinney College of Natural Resources at Utah State University

Additional Reading:

Dudareva, Natalia. 2005. Why do flowers have scents? Scientific American April 18. https://www.scientificamerican.com/article/why-do-flowers-have-scent/

Shultz, Leila. 2012. Pocket Guide to Sagebrush. PRBO Conservation Science. https://digitalcommons.usu.edu/sagestep_reports/20/
As pdf: https://rdjzr2agvvkijm6n3b66365n-wpengine.netdna-ssl.com/wp-content/uploads/2018/06/sagebrush_pock_guide_reduced.pdf

Shultz, L. M. 2006. The Genus Artemisia (Asteraceae: Anthemideae). In The Flora of North America north of Mexico, vol. 19: Asterales, pp. 503–534. Flora of North America Editorial Committee, eds. Oxford University Press. New York and Oxford.

USDA, NRCS. 2012. The PLANTS Database, National Plant Data Team, United States Department of Agriculture (USDA), Natural Resource Conservation Service (NRCS): https://www.plants.usda.gov

VanBuren, R., J. C. Cooper, L. M. Shultz and K. T. Harper. 2011. Woody Plants of Utah. Utah State University Press & Univ. Colorado. 513 pp. https://upcolorado.com/utah-state-university-press/item/2323-woody-plants-of-utah