30 



JOURNAI, OF THE ROYAL HORTICULTURAL SOCIETY. 



Poor Soils. 

 Spurrey. 

 Quaking Grass. 

 Eest Harrow. 

 Ox-eye Daisy. 

 Dyer's Green-weed. 

 Sheep Sorrel. 



Good Loamy Soils. 

 Groundsel. 



Goosefoot or Fat Hen. 



Chickweed. 



Sow Thistle. 



Cleavers. 



Buttercups. 



Damage Done by Weeds. 



It has from immemorial times been recognized that " weeds " are 

 harmful, even from the time of the Garden of Eden; and Shakespeare 

 says : — • 



I will go root away 

 The noisome weeds, that without profit suck 

 The soil's fertility from wholesome flowers. 



Eich. II. Act iii. sc. 4. 



One of the most obvious ways in which they do harm is by robbing 

 cultivated crops of space, food, and water, and of light and air, all of 

 which are necessary for the proper growth of the crop. The facts as 

 to space, light, and air will be obvious to all, for two plants cannot 

 occupy the same space, and the weed may cut . off the sun's light, while 

 a crop crowded with weeds is restricted in the Iree circulation of air 

 necessary for gaseous interchange. Weeds require food in the same 

 way as cultivated crops, and Stutzee and Seidler's analysis of certain 

 weeds show that the average dry matter in the annual sow thistle, 

 cornflower, Persicaria, spurrey, wild radish, and yarrow contained 

 2*38 per cent, of nitrogen, 0'93 of phosphoric acid, 3*08 of potash and 

 2*86 of lime, Persicaria being especially rich in all these constituents. 

 Weeds also transpire, or pump water up from the soil and pass it 

 into the atmosphere by their leaves — and this must be to the detriment 

 of the cultivated crop, especially on soils which dry out quickly and 

 in hot summer weather. 



Cultivation is much hindered by weeds, and singling " is often 

 particularly difficult owing to their presence, though, as we have 

 seen, weeds render tillage absolutely necessary if a crop is to be 

 obtained. 



Many weeds are poisonous; others are parasitic on cultivated 

 crops; some stop up drains; the value of seeds is often much reduced 

 by the presence of weed seeds; and weeds like cleavers, bindweeds 

 and wild vetches drag down and choke out crops, and may do great 

 harm among bush fruit trees (we have seen raspberry canes and 

 hedges almost smothered by the larger bindweed, Convolvulus 

 sepium). 



Another point of importance is that weeds act as host plants for 

 injurious insects and fungi, sustaining them until suitable cultivated 

 plants are plentiful. For example, the following insects and fungi 

 attacking garden crops find quarters on the weeds named: — 



