POLYGONACEAE (BUCKWHEAT FAMILY) 93 



so that they will be starved of the food assimilated by the leaves. 

 Or when the ground is very soft the roots may be removed entire, 

 by prying with a spade set into the ground vertically by the side 

 of the root and pulling hard at the same time with the other hand. 

 The roots of all three of the immigrant Docks here described are 

 used in medicine; and the United States annually imports more 

 than a hundred thousand pounds to supply the drug trade, at a 

 cost of about a half-million dollars. If properly cleaned, split length- 

 wise, and dried, they might be made to pay for the labor of their 

 extraction from the soil. 



WILLOW-LEAVED DOCK 

 Riimex mexicanus, Meisn. 



Native. Perennial. Propagates by seeds. 



Time of bloom : May to September. 



Seed-time: July to November. 



Range : Labrador to British Columbia, southward to Maine, Michi- 

 gan, and Minnesota, and along the Rocky Mountains to central 

 Mexico. 



Habitat : Moist, rich soil ; fields, low meadows, waste places. 



This weed is tolerant of soil which is somewhat brackish and 

 it often damages the hay crop from the salt-marsh meadows 

 along the Coast. It has also made its way to Europe, where it 

 is regarded with much dislike. 



Taproot rather stout, penetrating the soil to a great depth. 

 Stems tufted, slender, ascending, flexuous, grooved, smooth, and 

 pale green, one to three feet tall, usually simple. Leaves narrow, 

 lance-shaped, pointed at both ends, the sides often nearly folded 

 together; petioles rather short. Racemes erect, the whorls very 

 dense; pedicels scarcely exceeding the calyx-lobes, jointed near 

 the base ; calyx olive to reddish brown, the valves triangular- 

 ovate, delicately veined, all tubercled. Achenes dark red, smooth 

 and shining ; frequently an impurity of clover and alfalfa seed, so 

 extending the range of a most troublesome weed. 



Means of control the same as for Rumex crispus. In well-tilled 

 ground none of these large, deep-rooted weeds attain sufficient size 

 to be very troublesome. 



