What makes you think that?
Because there are the letters 's', 'a' and 'r' in sarsparilla. I would watch out then, as sarsparilla can also contain S.A.R.S. then
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Also, doesn't it seem obvious to you that, if sarsparilla would contain oil, it would be called 'sarsparilla oil' ?
UTFSE and search at Rhodium's to find out more about plants other than sassafras containing safrole.