254 Minnesota Plant Life. 



in Minnesota for these purposes, though it is evidently capable 

 of producing as strong a fibre here as elsewhere. The hemp 

 leaves are divided into from four to eight or nine slender lobes 

 arranged in palmate fashion. The staminate flowers are ar- 

 ranged in panicles, while the pistillate stand in short leafy spikes. 

 Nettles. The nettles are represented in Minnesota by the 

 stinging and the slender nettles, the wood-nettles, the clear- 

 weeds, the false nettles and the pellitories. The first two va- 

 rieties of nettles, one of which is introduced, are distinguished 

 by the different shape of their leaves. In the stinging nettle 



FIG. 119. Roadside vegetation of nettles and vines. Winter aspect. After photograph by 



Williams. 



the leaves are ovate in outline, while in the slender nettle they 

 are lance-shaped and slender pointed. Both of these plants are 

 provided with peculiar stinging hairs, consisting of cells with 

 very sharp points and swollen bases around which a group of 

 cells comes up like a cup. Hairs of this sort are found on both 

 the leaves and stem. Upon being brushed against, the ends 

 of these hairs break, forming a chisel-like point which penetrates 

 the flesh and the cup of cells around the base of the hair con- 

 tracts and injects irritating poison, very much as if from a syr- 

 inge. The peculiar stinging sensation which arises when one 

 touches a nettle is a result of this injection of acid into the flesh. 



