Valerian is a herb from which the drug Valium is NOT derived. No doubt, the similarities in naming comes from "Valium" attempting to mimic some feature, that of valerian.

It is a member of the family Valerianaceae. The root of the name (Valerian or Valerianacea) means "to be healthy" in Latin.

It is the root of the plant which is used.

The plant (specifically the root) gives off a distinctive scent which can best be described as "unpleasantly musty".

The plant is a perennial. Its seeds are slow-germinating. The plant does best (temperate situations) if the seeds are sown in spring, perhaps indoors and later transplanted. The plants are harvested in the second season of growth. Dry the roots for future use.

The plant can grow well under marshy conditions, but well drained is best. It develops pink flowers from June until August. It can grow quite tall.

Using Valerian:

The roots, when dried, ground and made into a tea, (or consumed in other fashions) is very calming and can help promote sleep in the sleepless. It is best not to drink it for a long period of time, but to drink it before bedtime for a few days -- then stop drinking it for a time.

Unknown, but it's in the literature - the leaves or roots, made into an ointment, is possibly suitable for relieving skin ailments.