268 



WEED FLORA OF IOWA 



Fig. 154-A. Distribution of Prostrate Vervain. 



with large bracts, small, purple ; trichomes few-celled from a broad 

 several-celled base. 



Distribution. — Common in waste places, roadsides, walks, gravel- 

 ly and sandy fields from Virginia to Wisconsin and Minnesota and 

 southward. 



Extermination.— It is easily exterminated by cultivation. 



LABIATAE, MINT FAMILY. 



The common pepperment, scarlet sage, catnip, pennyroyal, thyme 

 and basil belong to this family. All are aromatic plants. 



Mint (Mentha arvensis L.). 



Description. — This perennial weed has freely branching stems 

 1-1% ft. high, retrorsely pubescent, leaves oblong to ovate, rounded 

 at the base, minutely pubescent, closely serrate, petioled or nearly 

 sessile; flowers white, pink or violet. The varity canadensis has 

 lanceolate to oblong-lanceolate, pubescent leaves and is the common 

 form in Iowa in low grounds. Several other species occur in Iowa, 

 namely: peppermint (Mentha piperita) along brooks, a smooth 

 and pungent-tasting herb with ovate-oblong leaves and running 

 root-stocks, and spearmint (Mentha spicata) with oblong or ovate- 

 lanceolate unequally-serrate leaves. 



Distribution. — This Eurasian species occurs from Newfoundland 

 to Nebraska and the Pacific coast. 



Extermination. — Easily exterminated by giving thorough culti- 

 vation and dragging the soil to bring the root-stocks to the surface 

 of the ground. 



