Sentence:  Sections of sweet clover stem and <WSD>root</WSD> tumors were treated with 1 : 10 solution of * * f for 30 minutes , washed in buffered saline for 15 minutes , stained with * * f for 30 minutes , and washed for 15 minutes in PBS . 
Meaning of the word marked with <WSD> tags:  (botany) the usually underground organ that lacks buds or leaves or nodes; absorbs water and mineral salts; usually it anchors the plant to the ground