1911] The Ottawa Naturalist. 113 



There are a large number of plants possessing such irritant 

 juices. Some are well-known, like the Nettles, Poison Ivy, and 

 the much favoured little Primula (P. obconica), which is so grate- 

 ful a flowering plant during the winter months in our conserva- 

 tories. Experiments have been made with a number of closely 

 related primulas, all members of the P. Sinensis section. The 

 Chinese Primula itself has caused considerable irritation to per- 

 sons handling the plants. The leaves of this group of plants are 

 covered with fine glandular hairs, which contain the irritant 

 juice. It has been found that Primula Sieboldii Morr. , P.Arendsii 

 Pax., P. Mollis Hook., may also cause similar irritations. 

 Strangely, however, people unsusceptible to the irritation of 

 P. obconica have often suffered considerable annoyance from 

 these latter species. 



In examining the glandular hairs of these and similar plants 

 I once had the misfortune to sting myself very severely with a 

 Laportea from Australia (L. gigas). For weeks my arm was stiff 

 and swollen, and for months even years as soon as the hand 

 affected by the sting was put into cold water a severe pain 

 shooting right through the limb was felt. There grows on 

 Parliament Hill, right in the centre of Ottawa, another member 

 of the same genus, (L. canadensis), which has a decidedly un- 

 pleasant action upon some people. One of the men at the 

 Experimental Farm still bears large scars due to the effects of 

 this plant. 



Certain cruciferous plants with large brittle hairs cause a 

 smarting effect like Stinging Nettles, but much less severe. 

 The fine hairs covering the inside walls of some rosaceous fruits 

 also may cause a very troublesome irritation to the unprotected 

 skin. The glandulous hairs covering leaves and stems of some 

 of our wild orchids, especially Cypripedium pubescens,C. spectabile, 

 and C. parviflorum contain a secretion which acts much like 

 Primula obconica. 



Some records exist of an eczema-like inflammation of the 

 skin caused by handling Common Ivy (Hedera Helix). 



Humea elegans is another plant which causes frequent skin 

 irritations. It is a compositous biennial from Australia and is 

 one of the most beautiful herbaceous perennials, though little 

 known in Canada. 



No doubt there exist a number of other plants having similar 

 properties, but those mentioned have been repeatedly recorded 

 as having a decidedly disagreeable action on some persons. A 

 saturated solution of lead acetate in alcohol added to an equal 

 quantity of glycerine has been proven to be of the greatest value 

 in relieving the often unbearable irritations. 



H. T. Gussow. 



