Catnip is an introduced, naturalized erect perennial forb growing on 4-angled light green stems that are covered with fine hair and branch near the top. Stem branches are straight to ascending.
The leaves are opposite, triangular in shape with a heart-shaped base, covered with whitish fuzz, (more so on the underside) and on a slender stalk that is half as long as the leaf blade. Margins have coarse teeth and leaves show a fine reticulated network of veins. Leaves are aromatic, containing thymol, with an odor resembling thyme.
The inflorescence is a whorl-like dense cluster of flowers at the top of stems and lower on the stem, separate clusters at the leaf axils. There are small narrow bracts beneath the clusters and smaller bracts within the clusters. Additional spikes may arise on separate stalks from the upper leaf axils. These clusters on the stem are distinctly separated from each other both vertically and at the same stem node. In the mint family this arrangement is called a 'verticillaster' where the flowers look like a whorl arrangement but are actually in cymes that rise from the axils of the green hairy bracts that are opposite each other on the stem. Only a few flowers in each cyme open at one time.
Flowers are 1/3 to 2/3 inch long and have a tubular light green calyx with 5 awl-shaped teeth. There are also 15 raised longitudinal nerves (or ribs) visible on the calyx. This is a distinguishing feature of this genus. The corolla is whitish cream color with a two-lobed lip at the top and a 3-lobed lip at the bottom, the central lobe of which is much larger and has a lobed edge. It is the larger lower lobe that has pink to purplish dots. The entire outside of the calyx and corolla have fine hair. There are 4 stamens with deep red anthers, positioned near the upper lip, two on each side of the style.
Seed: Fertile flowers produce a capsule containing 4 brown smooth nutlets. Seeds planted in the Fall will germinate in the Spring.
Habitat: Catnip is normally found in dry disturbed sites, roadsides, waste places, old farmyards, and in cultivated herb gardens. In the Southwest it is often planted as an ornamental as it is one of the more drought resistant members of the mint family. It grows from rhizomes which can spread the plant vegetatively and by re-seeding.
Names: The genus, Nepeta, is derived from the old Etruscan city of Nepeta. Cats were liked by the Etruscans so there is sense to that and with the species, cataria, coming from the old Latin, cattus, for 'cats', it all makes sense. The alternate common name of Catmint, is a more generic name applied to many species of the Nepeta genus, particularly those that are developed by the nursery trade to be more ornamental and showy such as Nepeta faasenii ‘Blue Wonder’. The author name for the plant classification - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: Other members of the mint family have flowers in verticillasters and spikes near or at the stem tops. These would include American Germander, Teucrium canadense; Wild Mint, Mentha arvensis; and Hedge Nettles, Stachys, spp, and Motherwort, Leonurus cardiaca.
Above and below: The inflorescence is a whorl-like dense cluster of flowers at the top of stems, and smaller groups in the upper leaf axils, separated on the stem from the cluster at the top. The small bracts beneath the cluster are visible in the photos.
Below: 2nd photo - Flowers produce a dry capsule containing 4 smooth brown nutlets. Note the nerves and the remains of the pointed lobes of the calyx still visible on the dry capsules.
Below: 1st photo - Catnip branches freely in the upper part of the stem - straight to ascending branches. 2nd photo - Both calyx and corolla have dense fine hair. The center lower corolla lip is much larger with a lobed edge. 3rd photo - The opposite leaves are triangular with coarse teeth, fine surface hair and reticulated veins.
Below: 1st photo - side view of the corolla and calyx with its five pointed teeth. 2nd photo - calyx detail showing the 15 darker green nerves. Fine hair on all outer parts. 3rd photo - Detail of the hair on the angled stem and the underside of the leaf.
Below: An example of a nursery trade plant marketed as catmint - Nepeta faasenii ‘Blue Wonder’, which spreads outward in a large clump instead of forming a tall stalk.
Notes: Catnip is generally considered indigenous to the garden area, although Eloise Butler made no mention of it in the early years of her Garden Log. She did mention it in her 1915 article, The Fragrance of the Wild Garden, so we assume it was definitely present. By the time of Martha Crone's 1951 census it was gone. It is a plant introduced from Europe and Asia and is now naturalized throughout North America except the very far north Canadian Provinces. It is found in over half the counties of Minnesota. This is the only species of Nepeta known to be in Minnesota.
Medicinal & practical uses and lore: Catnip is the plant that when bruised gives off aromas so beloved by cats. It seems to have an intoxicating affect on them. Living plants that have not been bruised and not giving off an odor are usually not bothered, but once bruised or dried, the cats love it, or as Michael Moore wrote (Ref. #30) "the animal will grovel, drool, and make a benign fool of itself." Catnip while not extremely showy, makes a good border plant when used with hyssop. Catnip has a long history of folk medicinal use. Mrs. Grieve (Ref. #7) reports that the English brewed Catnip Tea before the importation of tea from China. (Catnip must be infused, never boiled, to make tea). In folk medicine the flowering tops were collected when in full bloom to make an infusion drunk as you would tea. This treated fever, colic and nervousness and headaches. Tilford (Ref. #39) likewise recommends the plant for a tea, it being high in vitamins and trace minerals. Young leaves and buds are edible and added to a green salad with a lemon or herb vinaigrette are said to be delicious. Densmore (Ref. #5) reports the Minnesota Chippewa used a decoction of the leaves to treat fever.
Culpepper (Ref. #4b) described a number of old uses including the following: "It is effectual for any cramp or cold aches, to dissolve cold and wind that afflict the place, and is used for colds, coughs, and shortness of breath. The juice thereof drank in wine, is profitable for those that are bruised by any accident. The green herb bruised and applied to the fundament, and lying there two or three hours, easeth the pains of the piles; the juice also being made up into an ointment, is effectual for the same purpose." (Ref. #4b ; page 223, The English Physician Enlarged.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"