Is the Common Teasel (Dipsacus fullonum) Carnivorous or was Francis Darwin Wrong?

Francis Darwin first suggested common teasel (Dipsacus fullonum), a biennial species, might be a carnivorous plant. He suggested this species acquires nutrients from insects that drown in water-holding cups formed at the base of leaves that surround stems. Since then, other biologists have made the same claim. To test this we addressed the question: does adding invertebrates as supplemental nutrients to water-filled cups of D. fullonum influence reproduction or are nutrients only obtained from the soil? We performed two factorial designed experiments (high-nutrient soil vs low-nutrient soil) x (fed vs control) to test this. Fed treatments involved either crickets or liquefied animal solution. We performed a third experiment where teasel plants were grown in nutrient deficient standard carnivorous plant soil mix to determine if prey supplement influenced growth and reproduction. These experiments revealed that soil nutrients alone influence growth and reproduction. More seeds were produced by plants grown in high-nutrient soil; while curiously, a higher percentage of seeds germinated from plants grown in low-nutrient soil. When teasel rosettes were grown in carnivorous plant soil, plants did not grow, produce stems, or flower even with animal solution. Thus we found no evidence suggesting common teasel is carnivorous.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author