12931
Estimates in the literature as to what extent the world ' s higher plant species have been studied chemically or for bioactivity are contradictory and range from 0 . 5 % to > 12 % .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None