Ohio Perennial and Biennial Weed Guide

Family:

Mint Family (Lamiaceae)

Other Names:

catmint, catnep, catrup, cat's-heal-all, cat's-wort, field-balm, nep, nip.

Origin and Distribution:

It is uncertain if catnip is a native of Europe or Asia, but it is agreed that it was introduced to North America from Europe. In North America, it was frequently cultivated but escaped and is now found throughout northern U.S. and Canada. Catnip is widespread in Ohio. The plant grows best in rich soils, but it readily establishes in a variety of habitats. It can be found in pastures, fence rows, barnyards, stream banks, and waste places such as dumps and parking lots as well as growing along roadsides and railroads.

Plant Description:

Catnip is an erect perennial best known for the minty odor emitted by its leaves and stems when they are crushed or wilted. The odor is very attractive to cats. Other distinctive characteristics are downy foliage and the serrated appearance of the leaf edges, which resembles the toothed edge of a saw. The flower shape is common among members of the mint family consisting of 2 lips, and flower color is white with unusual purple dots. Along with most members of the mint family, catnip has square stems. This species reproduces by seeds and it also produces short rhizomes (horizontal underground stems).

• Root System:

  The root system forms a taproot and eventually short rhizomes (horizontal underground stems).

• Seedlings and Shoots:

  Initially emerging are 2 seed leaves (cotyledons) that have downy hairs covering their upper surface, edge, and leaf stalk (petiole) and a hairless lower surface. Thereafter, leaves and petioles are covered with hairs.

• Stems:

  Stems are erect, 1 to 3 feet tall, square, pale green, branched, and covered with short white hairs.

• Leaves:

  Leaves are opposite (2 leaves per node), hairy, triangular or heart-shaped, and have pointed tips. The upper surface is pale green and the lower surface is so densely covered with hairs that it appears whitish. Leaf edges are serrated in such a manner that they resemble the toothed edge of a saw blade. Leaves attach to stems by way of long slender petioles. If crushed or wilted, leaves give off a characteristic minty odor.

• Flowers:

  Flowers are 1/2 inch long and have 5 petals united into a 2-lipped tube. The upper lip consists of 2 lobes while the lower lip has 3-lobes and is larger and more spotted than the upper lip. Flowers are white to pale lavender with purple spots. Dense whorled clusters of flowers form at the ends of stems and branches.

• Fruits and Seeds:

  Each flower produces a pod containing 4 seeds. Seeds are oval, smooth, red-brown, and have 2 white spots at one end.

Biology:

Catnip flowers between June and October. The plant can be controlled using clean cultivation. In areas where cultivation or hoeing is not possible, repeated mowing can be used to control the weed. Mowing should begin in the spring and be repeated often enough to prevent shoot growth.

Toxicity:

None known.

Facts and Folklore:

• Latin's named the plant 'Nepeta' after an old Italian town called Nepete where the plant either was encountered for the first time or grew in great profusion.

• 'Cataria' is thought to be derived from the Latin word for cat.

• Historically, catnip has served a number of uses. It was a common home remedy used to treat complaints of pregnant women, childhood colic, fevers, and pneumonia. Today, catnip is entered in the U.S. Pharmacopoeia as a mild aromatic.

• The minty smell of catnip is very appealing to cats, many of whom respond with a unique pattern of behavior. Legend states that a leaf from the plant will turn a touchy old cat into a frolicking kitten. Cats are attracted to catnip plants that are bruised or withered. However, not all cats respond to catnip and the attraction has been shown to be inherited.