A three-leaved example. These were growing on a bit of a mound and on the lower half most of them were 4-leaved and the upper half they were mostly 3-leaved. Note: On later examination I believe that the plants that appeared to have 4 leaves were actually 3-leaved but with multiple sets growing in such a way to make it look like there were 4. (Pyrola uniflora) is also known as (Moneses uniflora).