Question: What time zone is used in the place that has an official symbol of Populus Tremuloides?
Answer(s):
answer: Mountain Time Zone

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ?c)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
?c ns:government.governmental_jurisdiction.official_symbols ?k .
?k ns:location.location_symbol_relationship.symbol ns:m.0fvj76 . 
?c ns:location.location.time_zones ?x .
}