WEEDS OF ARABLE LAND 129 



the awned " seed " being covered with reddish-brown 

 hairs. In the cultivated oat the spikelet contains two 

 or three flowers, only the lower of which is awned, and 

 that not always ; when present, the awn is straight. 



Closely resembling this weed is the Bristle-pointed 

 Oat (A. strigosa Schreb.), the spikelets of which contain 

 two flowers : its flowering glume is more deeply divided 

 at the apex, the two segments being shortly awned. 

 Both the above species flower from June to August. 



It is of the utmost importance that only pure seed 

 grain be sown, and seed corn from a field in which 

 either of these weeds have occurred should be banned. 

 Whenever they have been observed the succeeding 

 root crop should be thoroughly cleaned, and the seeds 

 which were shed before the corn crop was harvested 

 encouraged to germinate, after which the young plants 

 may be destroyed before they produce seed. Pure 

 seed and thorough cultivation of root crops will exter- 

 minate these weeds. In a barley crop the Wild Oats 

 may be removed by hand. 



Annual Meadow Grass (Poa annua L.) is useful as a 

 component of grass land, but is an exceedingly trouble- 

 some and ubiquitous weed on arable land, in gardens, 

 and on gravel paths. This little grass (Fig. 38) is an 

 annual, 6 to 1 2 inches high, with weak spreading stems, 

 and green or purplish panicles, i to 3 inches long, of 

 small, almost sessile spikelets. Seed is produced abun- 

 dantly from April to September, or later. The plants 

 are often so small, that flowering and seeding goes on 

 among larger plants without being observed. In field 

 cultivation, surface tillage encourages the seeds to ger- 

 minate, after which harrowing -in hot weather will kill 

 the young plants. Hoeing of root crops usually keeps 

 the weed within bounds. In gardens the continual use 

 of the hoe should be practised, and care must be taken 



I 



