A valid but very unlikely interpretation, which is the point. Every query is ambiguous, but if certain interpretations are much more likely than others, the search engine should respond accordingly.
Someone interested in a list of elm species is much more likely to search for "elm species."
It may be that this is true of people who use google but less true of people who use Bing.
It is very unlikely to be the case. Much more likely is that Bing either doesn't have enough search data to properly answer that query or does not have a ranking model that can answer that query correctly.