A Sylvan Jar is a minor magic item used to store medicinal and magical herbs, as well as potions, salves, ointments, etc. Anything stored in a Sylvan Jar will stay fresh, and retain it's potency for an indefinite amount of time. They can be clear or colored, and are usually etched with vines, or plants, as a decoration. Some are labeled with Elvish glyphs to indicate it's contents. The jars can come in all shapes and sizes, but large ones are rare. A jar will have either a cork, or glass stopper, and the effect will not work if the stopper is missing, or left off the jar too long. Although the jars are extremely durable, they can be broken.
The secret to the creation of a Sylvan Jar has long been lost, and many glassblowers would pay dearly to learn the secret of creating them. Rumors abound of a long, lost tome that describes how they are made.
These are highly prized by alchemists and herbalists, and most will pay a good price to acquire a Sylvan Jar.