THE BUCKWHEAT FAMILY 41 



Sheep Sorrel. The seeds are shaped like those of the buckwheat, 

 being triangular in cross section; or, as the name buckwheat 

 (which is merely a corruption of beechwheat) indicates, shaped 

 like small beechnuts. There is no true corolla, the seeds being 

 surrounded merely by the six-parted calyx, three divisions of 

 which are small and the other three large, winglike and variously 

 shaped and veined in the different species. One or all three of 

 these wings may bear a seedlike, corky tubercle on the outside. 

 The seeds of all species are much alike, and the winglike calyx 

 divisions, often found attached to the seeds, are a great help 

 in identifying the different species. 



While a certain number of the Docks are native, all the 

 worst varieties have been imported with foreign clover seeds; 

 several are already agricultural pests. 



Smartweeds and Knotweeds have various habits of 

 growth, being, with few exceptions, herbaceous plants with 

 fibrous roots, annual or perennial, terrestrial or aquatic, erect 

 or prostrate, climbing or floating. Of the many different groups 

 which can be easily distinguished, three are important as in- 

 cluding weeds: 



1. The group "Avicularia" : mostly prostrate, smooth annuals 

 with small linear oblong leaves, represented by Doorweed 

 (Polygonum aviculare L.). 



2. The group "Persicaria" : generally tall, annual, erect, 

 branching plants, with larger lance-shaped leaves, represented by 

 Lady's Thumb (Polygonum Persicaria L.). 



3. The group "Tiniaria": twining annuals and perennials, 

 with heart-shaped leaves, typically represented by Black 

 Bindweed (Polygonum Convolvulus L.). 



The seeds are lens-shaped or triangular, with blunt edges, 

 generally dark-colored, shiny and have the general characteristics 

 of the family, but the divisions of the enlarged fruiting calyx in 

 which they are enclosed are not winglike as in the Docks. They 

 ripen late and are commonly found in clover and grass seeds. 



