Root like structures found in mosses and liverworts. used to anchor plant to the substrate, may draw water towards plant through capillary action but no specialized water absorbing tissue (no xylem)

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.