Answer:
In spring I look gay, Covered in a green array, The warmer it gets the more clothing I wear, As the cold grows, I throw away my clothes.
It goes up and down the stairs without moving.
What occurs four times in every week, twice in every month, only once in a year but never in a day?
How can a pants pocket be empty and still have something in it?
What goes through towns and over hills but never moves?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.