22 



WEEDS. 



guarded against in the " common thistle ; the stems can be 

 kept down by repeated cuttings. In order to eradicate the 

 tapering and spreading, no process is so effectual as " deep 

 ploughing," executed with a strength of four horses, and the 

 furrow narrow in proportion to the depth, that no roots escape 

 uncut between the furrow slices. This mode of deep and nar- 

 row ploughing never fails in completely expelHng the thistle 

 as a weed on cultivated grounds. 



16. The common Dock," or the "Rumex" of botanists, 

 is a very annoying weed both in cultivated lands and on pas- 

 tures, in soft damp soils. It belongs to the class and order 

 " Hexandria trigynia" of Linneus, and the natural order 

 " Polygonese" of Jussieu. 



Generic character. — Calyx : perianth, three-leaved ; leaflets 

 obtuse, reflex, permanent. Corolla : petals three, ovate, bigger 

 than the calyl, and, like it, converging, permanent. Stamina : 

 filaments six, capillary very short ; anthers erect, twin. 

 Pistil : germ turbinate, three-sided ; styles three, capillary 

 reflexed, standing out between the clefts of the converging 

 petals; stigmas large, laciniate. Pericarp none. Corolla 

 converging, three-sided, inclosing the seed. Seed single, three- 

 sided. 



Essential character. ^Cdilyx three-leaved ; petals three, 

 converging. Seed one, three-sided. 



The " Rumex obtusifolius," or " Blunt-leaved dock," is the 

 most common weed. Flowers hermaphrodite ; valves toothed, 

 one chiefly graniferous root. Leaves cordate, blunt. Stem 

 somewhat rugged. Root tapering, running deep and straight. 

 Stem three feet high, upright, branched. Racemes nearly 

 upright, furnished with few leaves. Flowers in half whorls, 

 on capillary peduncles, sprinkled near the top with white 

 shining globules, and the pedicles surrounded near the base 

 by an indistinct cartilaginous ring. 



The " Rumex acetosa," or the " Common sorrel," has a 

 perennial root, running deep into the earth. Stem mostly 

 simple, erect, from one to two feet high. Flowers dioecous ; 

 valves graniferous. Leaves oblong, sagittate. It flowers early 

 in June. 



