This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Introduced. Perennial. Propagates by seeds and by rootstocks.
Fig. 243. -Catnip or Catmint (Nepeta Calaria).
X 1/4.
Time of bloom: April to July.
Seed-time: Late May to August.
Range: Newfoundland to Ontario and Minnesota, southward to Georgia and Kansas. Habitat: Moist or shady soil; lawns and yards, waste places.
In old days, before the hop took its place, this plant was used for flavoring and clarifying the home-brewed ale. Like the Plantain, it seems almost domesticated and is a familiar weed about dwellings and in towns.
Stems slender, prostrate, and creeping, with many small, ascending branches, very leafy, three to five inches high. Leaves rounded or kidney-shaped, scallop-toothed, green on both sides, with slender petioles. Flowers in small axillary clusters, pale purple, spotted with deeper purple; corolla about a half-inch long, its upper lip with two lobes, three lobes in the lower lip, the upper pair of stamens nearly twice the length of the lower ones, rising against the upper lip; the tube more than twice the length of the five-lobed, hairy calyx. The four small nutlets ovoid and brown.
It is almost impossible to dig out this weed and get all of the slender, creeping rootstocks. If the infested ground is a lawn the surest method is to skin off the rather shallow layer that contains the roots and probably also a good supply of the seeds, and relay with new sod or sow with clean seed.
 
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