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Reproductive success of tall boneset in the Quarry Bottom of the Nature Park

Brett Bohlander, Debbie Jewell, Dan Zindrick, and Ryan Heffernan

Class project for Ecology, BIO 342, fall 2005

Tall boneset seems to be most abundant
on the tops of rock mounds in the quarry
bottom at the Nature Park.

Tall boneset (Eupatorium altissimum ) is a perennial wildflower in the family Asteraceae.  The plants grow up to 3 meters tall.  The plant produces conspicuous white flowers with flat tops. The plant tends to grown in sandy soils in open or recently disturbed areas.

In the quarry bottom of the Nature Park, we noticed that the plant appears to be more common on rock mounds than on surrounding flat surfaces.  Based on our initial observations, we hypothesized that the plant would experience higher growth rates and higher reproductive success on rock mounds than on flat surfaces. 

We selected five mounds in the quarry bottom and set up 10 m transects, starting at the top of each mound and running downhill in a random direction.  At 1 m intervals along each transect, we recorded the number of plants, heights of plants, and number of flowers per plant.  We also collected soil samples to measure soil moisture levels and soil texture. 

Plants were non-randomly distributed along each transect.  Highest proportions of plants were observed at the top of each mound with nearly uniform declines in numbers of plants as distance from the top of the mound increased. 

Tall boneset (Eupatorum altissimum) is a
perennial wildflower, 1-3 m tall, with
conspicuous white flowers clustered
on a flat top.

Plants growing on the top of the mounds had longer roots, higher biomass, and higher numbers of flowers than plants growing farther away from the mound tops.  Soils were drier and were composed of more large rocks at the top of the mound than off the mound. 

We conclude that white boneset grows best in dry soils with rocky textures.  We’re not sure why dry mounds provide more favorable growing conditions for the white boneset.  We recommend that future research on this plant be conducted to look at seasonal trends and soil pH.  Our research has significant conservation implications given that this plant species is endangered in Indiana.