Valerian (Valeriana officinalis) is a hardy perennial flowering plant, with heads of sweetly scented pink or white flowers. Note that this "sweet" smell is quite overpowering when you put the flower into a vase. It is strong enough to give some people headaches. Valerian has uses in herbal medicine as a sedative. The main current use of valerian is as a remedy for insomnia.

All species of valerian work, some more strongly, some less so. The aboveground parts of the plant are weaker than the roots, and the fresh herb is weaker than the dried herb. Valerian is traditionally brewed into tea, but many people find the smell unpalatable; the herb is now sold in capsules, which avoids this difficulty.

About 10% of the population cannot take full-strength valerian; they get headaches and feel groggy in the morning, after taking the tea as a sleep aid in the evening. They might benefit from lower doses. Mid- to long-term use of this plant (~ 2 weeks) might result in emotional upsets. Bouts of hysterical laughter, deep sadness, or rage, without any seeming cause, are symptoms.

An unusual feature of valerian is that pieces of the dried root affect the domestic cat in the same way as catnip. If valerian root is left in a place where cats have access to it they will roll in it, drool on it, and chew it. However some cats won't touch valerian root.

Classification: Valerian is in the Valerianaceae -family. It has also been seen in the family Caprifoliaceae, order Dipsacales.

There are lots of different genera in the Valerianaceae family. All have more or less the same effect as valerian. For instance, the aboveground parts of Red valerian, Centranthus ruber, a common weed in parts of Europe, Asia and North America, can be used like the aboveground parts of valerian.

And no, Valium is not derived from Valeriana: http://www.ibiblio.org/herbmed/faqs/medi-2-1-valeriana.html#valium