1909.] 



Couch " or " Twitch. 



279 



"COUCH" OR "TWITCH." 

 Professor John Percival, M.A. 



Director of the Department of Agriculture, University College, Reading. 



The terms "couch," "twitch," "scutch," and " whickens " 

 are often applied by farmers in a general sense to several 

 perennial grass-like weeds which creep on or below the surface 

 of the soil. 



The three species of grass usually known by the name 

 "couch " are : — 



(1) True "Couch" or "Twitch" (Agropyrum rep ens, 

 Beauv. ; Triticum repens, L.). 



(2) Black "Twitch" or common Bent grass (Agrostis vul- 

 garis, With.). 



(3) Onion "Couch" (Arrhenatherum avenaceum, Beauv.; 

 var. bidbosum, Lindl.). 



These are among the most troublesome of all weeds of arable 

 land, and when once established a great deal of expense must 

 be incurred before the land is again clean enough for the 

 growth of paying crops. 



True " Couch " or " Twitch." — This is one of the most com- 

 monly distributed of European grasses, and grows on a great 

 variety of soils. It is rarely present in pastures and meadows, 

 but is found in almost all hedgerows and upon banks separat- 

 ing or bordering arable fields, and rapidly spreads from 

 these situations over the cultivated land unless steps are taken 

 to check it. The plant has whitish fleshy rhizomes, or under- 

 ground stems, at the nodes or joints of which buds are pro- 

 duced, and also adventitious roots (Fig. 1), From the buds 

 arise the upright growing stems, which come above ground 

 and bear the ordinary green leaves, and ultimately the ears or 

 inflorescences of the grass. The leaves are generally some- 

 what hairy on the upper surface, and at the point where the 

 sheath and blade meet there are two hook-like ears or auricles 

 which practically clasp round the stem. The ears or inflores- 

 cences (Fig. 2) are placed at the end of the stems, which are 

 1 to 4 ft. long, and the ears are built on the same plan as those 

 of wheat, the spikelets being arranged in two rows alternately 

 on opposite sides of the main axis or straw. Each spikelet 

 consists of three to five flowers, and is placed so that its flat 



