Catnip
Nepeta cataria
Closely related species:
N. ×faassenii (N. racemosa Lam. × N. nepetella L., also known as N. mussinii hort.) a garden cultivar, also known as catnip and loved by cats.
Synonyms:
Catmint, catnep, catwort
Family:
Mint family, Lamiaceae
Where to find this herb :
It's quite rare in the wild in Northern Europe; keep it in your garden.
Part(s) used:
whole herb
Special constituents:
nepetalactone, nepetalic acid, nepetalic anhydride, a- and ß-citral, limonene, dispentine, geraniol, citronellal, nerol, ß-caryophyllene, and valeric acid
Correspondance:
14 (Cunningham)
Uses:
the oil: in the perfume industry. Leaves and flowers: for a sedative tea, or to tempt cats
Kattekruid 
Katteurt 
Catnip is a bushy, rather strongly scented herb of the Mint family. Personally I'm not too fond of its scent; so I haven't tried making tea of it, although it should have a nice sedative effect. It has, in fact, been widely used for this purpose. It should also relieve menstrual cramps and tension headaches, and even babies and small children can be given catnip if they cannot sleep or have stomach cramps. The main constituent, nepetalactone, is a terpene with a similar structure to valepotriates derived from Valerian. The essential oil of Catnip is widely used in the perfume and pharmaceutical industry, for its scent and effect, and also to put in toys for cats.
Catnip is, of course, famous for its effect on cats. Not all cats react to Catnip; a certain gene is needed, and about 20% of cats are "immune" to Catnip. Kittens don't react to the herb until they are about 3 months old.
Cats that do react to catnip do so in individual ways. The responses include chewing the plant, rubbing on it, rolling in it, purring, sniffing, licking. Some argue it's a sort of sexual response; others claim the herb has a opium-like effect on the cats, sedative and pain-relieving, as well as acting as a stimulating agent. Sounds nice! No wonder cats love this plant.
In large doses, it causes vomiting in both cats and humans. Otherwise, it's completely safe to use for all. Cockroaches don't like it, though - you can use Catnip extract to repel those nasty little bugs.
You can dry the plant and sew into little bags for your kitty. Unfortunately, the dried catnip loses its scent quite quickly. Besides, your cat will extract all the goodies from the bag, whether by chewing or tearing, within a few weeks. Time to harvest more! If you buy dried catnip, and your cat doesn't react to it, it may simply have been on the shelves for too long. Better grow your own. Catnip is easy to grow, and you can also keep it in a pot indoors (where your cat can't reach it). Your outdoor Catnip may also need some protection - see the second picture above! Also, keep your Catnip healthy and strong by providing rich, alkaline soil. It's a perennial, and will also seed itself out to a certain degree.