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Gall placement and success on adult boneset plants

Brian Allman, Morgan Grant

Eupatorium perfoliatum grows in moist woods, thickets, and swamps.  Previous research has shown that galls on boneset are similar to galls on goldenrod plants.  

We tested these two hypotheses:

1.)  Location on the plant is correlated to the success of the gall
2.)  Location on the plant is not correlated to success of the gall

Success of the gall was measured as the number of fly larvae found in the gall.  We measured stem length, gall position, gall diameter, number of larvae in gall, and gall placement (main stem vs. side stem).  

We found a significant correlation between gall diameter and number of larvae in the gall.  Gall size is correlated to number of larvae inside the gall.  The placement of a gall on the main or side stem of a plant is correlated with gall size.