According to the "Tang Yun" (Tang Rhymes), the pronunciation is wu, with the fanqie "wu hu". The "Ji Yun" (Collected Rhymes) mentions that "cu xiao cao" is a type of plant found in the "Chu Ci" (Songs of Chu). The "Yu Pian" (Jade Letters) states that it is a type of grass resembling mugwort. Furthermore, the "Ji Yun" records that it is the same character as "su". The "Yangzi Fangyan Zhu" (Commentary on the Dialect of Yangzi) says that people in the Jiangdong region call "ren" by the name "cu". In the "Lei Pian" (Collected Sections), it is sometimes also written as.