Animals usually represent the body and the voice of the flesh. The tarot considers this an important element of a person and takes it into account as a character itself. When Strength controls the lion's mouth, she is talking about the mind being in control of the body without hating it. When the snake weaves tales for The Lovers, it is really the possibility of new sensations teasing the mind into wondering if peace is boring. Plants are the same, laden with double-meanings.
Roses are desire.
One rose held would be desire controlled. Being surrounded by an abundant field of roses would mean the fool is in a place where desire grows naturally and unchecked. A garden of roses would be desire cultivated to a pleasing and tame thing for the mind to enjoy. Trees speak of growth and earthly strengths. Almost every man the fool will meet has a wooden staff of some sort.