grows would be the verb.
The nouns in the sentence are tree and the compound noun backyard.
Rice is grown in his field by him.
The sentence is not a preposition but, it does have a preposition in it: outside.
I love cookies.We are here.She grows roses.Puppies are fun.
she wrote a long essay about what she wanted to be when she grows up.
The word rarely is the adverb, as it describes when or where the poison ivy grows.
He wants to be a movie producer when he grows up.
Inflation of goods and services occurs when the economy grows.
He dislikes growing tomatoes.
Astronomical: He wants to be an astronomical astronaut when he grows up.
Very.