From your description, it sounds like the charcoal cannister. This collect and stores vapors from you gas tank while the car isn't running to prevent them from beign released into the atmosphere. When the engine is running, The manifold vacuum draws air through the charcoal and sucks the vapor into the manifold to be burned.

Not a criticla component, but I's get the hose properly replaced. You'd fail an inspection without it and there is a very small risk of a fire since you could be venting a small amount of fuel vapors into the engine bay. Should be a cheap part to replace.