The place of marsh is divided into three levels such as lower, middle and higher. The lower marsh always is wet. The middle marsh sometimes is wet, while the higher marsh rarely wet. The higher marsh becomes wet only in the case of snow and rain.

Most area of the Senjogahara is the middle marsh, and the Yachi-bouzu (Floating sedge) is frequently seen in the middle marsh. Yachi means marsh in Japanese, and Bouzu means close-cropped head in Japanese.