Are you asking about the two traditional Chinese medicines of Imperata cogongrass and reed root?

The main difference is that the diameter of the Imperata cogongrass root is about 3 mm solid, while the reed root diameter is about 1 cm hollow.

To distinguish the above-ground part, Imperata has no stem and the plant height is 25-80 cm; reed has a hollow stem (similar to bamboo) with a height of 1-3 meters, and the diameter is related to the growth environment. Generally thin (2-5mm), the stems growing in ponds can grow up to 1.5cm.