- The genus is about equally divided into two subgenera, those with pedicellate flowers (Trillium L.) and those with sessile flowers (Phyllantherum Raf.).
- It continues to grow with a dome shape, but it can be sessile or pedunculated.
- It frequently occurs in the lower uterine segment and may be either sessile or pedunculated.
- These two phenomena are especially critical for sessile higher plants.
- The tumors were described as pedunculated or sessile polypoid nodules or as cauliflower-like masses projecting into the lumen of the gallbladder.