Problem: What are the most important words?
The caboose of a train at a station on a sunny day.
Answer: caboose, station, train

Problem: What are the most important words?
A railroad track traveling underneath a bridge in the day.
Answer: bridge, track, travel

Problem: What are the most important words?
the gnarled roots and trunk of an eucalyptus tree growing next .
Answer:
gnarl, grow, tree