Sentence:  Root and <WSD>stem</WSD> tumors from sweet clover plants infected with WTV were quick-frozen in liquid nitrogen , embedded in ice , and cut at 3 - 6 | m in a cryostat maintained at - 16 ` to - 20 ` . 
Meaning of the word marked with <WSD> tags:  a slender or elongated structure that supports a plant or fungus or a plant part or plant organ