Wildflowers as Indicator Species

April 14, 2014
Wildflowers-as-Indicator-Species
iStockRed trillium prefers to grow in moist, nutrient-rich soils.

Wildflowers are not only beautiful; they also tell us a lot about where they—and we—live.

“If you’re walking through the woods and you see a pretty dramatic change in the plant community,” says AMC staff ecologist Doug Weihrauch, “take a look around and try to figure out why.” Changes in the wildflowers will often reflect differences in the soil, or in the climate and topography of the area.

For example, a plant called the sensitive fern is an indicator of wetlands, where it thrives. This fern’s sterile fronds fall off after the first frost, but each plant’s single fertile frond stands like a dried sentinel through fall and winter and into spring. If you spot that dark brown central stalk dotted with balls of spores, which looks “like a rattlesnake tail,” or see the whole plant in the warmer months, chances are excellent that you’re hiking near wetlands, Weihrauch says.

The trillium family offers other information. Painted trillium, which has white petals with a pink stripe down the middle, grows best in acidic, dry, cool sites, while the related red trillium or bloodroot, which has deep red petals, prefers moister, richer soil. The two may grow somewhat close to each other, but their different locations indicate small-scale changes in the forest. “The enrichment that attracts the red trillium may be from a slight depression in the land, where it’s moister and there are more nutrients,” Weihrauch says. The lady-slipper and mayflower, two wildflowers in other families, also indicate small-scale changes; they love the low pH, acidic soil found underneath oaks, pines, or spruce.

A wildflower’s presence may mean different things in different places. For example, in northern New England, the blue-bead lily is a generalist that is widespread, Weihrauch says. In southern New England states such as Massachusetts and Connecticut, though, it indicates an area with a relatively cold climate—either a higher elevation area or a basin or valley with cold air passing through. Above treeline, the same flower means something else altogether: There, the blue-bead lily is an indicator of relatively warmer, sheltered areas.

“It can be a little tricky,” Weihrauch admits. “You have to know both the plants and where you are.”

Climate change is also reflected in the distribution of wildflowers at our feet. “We are losing more of the cool-climate species,” Weihrauch explains. “They are migrating farther north.” One example is mountain wood sorrel, which is now seen in Massachusetts only in high-elevation or northern regions, and is therefore more likely to disappear from the state altogether. New wildflower species are starting to appear in the region, moving up from the south.

And, of course, some wildflowers thrive throughout our region. When you see such generalists on your hike—like starflower, wintergreen, or trailing arbutus—well, they aren’t indicating much more than the happy fact that it is spring.

LEARN MORE

Find out more about wildflowers that thrive on mountaintops in the newly updated Field Guide to the New England Alpine Summits, 3rd ed., by Nancy G. Slack and Allison W. Bell.

 

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Heather Stephenson

AMC Outdoors, the magazine of the Appalachian Mountain Club, inspires readers to get outside and get engaged. Learn more.