142 LETTER XXXIX. 



It therefore differs fi'om the Nettles m having 

 booted stipules, uniform flowers, and triangular fruit, 

 and from the Amaranths, in having stipules, trian- 

 gular fruit, and an inverted embryo. There is no- 

 thing else within your acquaintance with which it is 

 necessary to compare it. Hence the Buckwheat 

 Tribe, the species of which, however different from 

 Knot-grass, agree with it essentially, is a peculiar na- 

 tural order, cut off by strong lines of demarcation 

 from all that surround it. 



Knot-grass itself, I have already said, is a species 

 of Polygonum, and there are many other wdld plants 

 belonging to the same genus ; of these P. hydropiper 

 and Persicaria, with their short, rounded spikes of 

 pink calvxes, are common examples ; in the gardens 

 P. orientale, or Garden Persicaria^ with its crimson 

 panicles, is one of the showiest of annuals ; and in the 

 fields Buckwheat^ or Beechwheat (Polygonum Fago- 

 pyrum), so called from the resemblance of its little 

 hard-brown seed-vessels to Beech-mast, with its beau- 

 tiful rose-coloured flowers, is commonly cultivated for 

 its seeds, of which pheasants are remarkably fond, 

 and from which is prepared the flour from which in 

 part crumpets are made. 



But these are far from all ; Docks, the detestation 

 of the farmer, with all their hedge varieties or spe- 

 cies, and Sorrels, which the French cooks value so 

 much, notwithstanding their unwholesome acidity, 

 are different species of Rumcx ; while Rheum boasts 

 of the useful Rhubarbs, whose leaf-stalks afford a 

 pleasant substitute for gooseberries in the early spring. 



