36 The VntiETAiiLK ExEiMiKs OF Mankind. 



fruit ends in a long tail, which has the property of curling itself 

 up when the air changes from moist to dry. The point of the 

 fruit is hard and sharp, and when it falls or is blown upon a 

 sheep's back the tail catches in the hairs of the wool, and by the 

 corkscrew twisting which takes i^]cice the sharp point is forced 

 into the skin of the sheep, and sets up inflammation, which often 

 kills the animal. Examples of this kind are Stipa capillata, 

 which is common in Russia. A North American species is Stipa 

 spartea. Another is Aristida Hygrometrica in Queensland, and 

 Heteropogon contortus in New Caledonia. The Harpagophyton 

 or Harpy jjlant of South Africa is almost as bad, but with this 

 diffei-ence, that its spiney fruits get into the mouths of grazing 

 cattle and produce laceration, or into the hoofs of the puny buck 

 or the antelope with a similar result. Other plants become a 

 nuisance to mankind on account of their taking to the water and 

 interfering with his navigation. Of these the Sudd of the Upper 

 Nile is the best known. It is not one plant, but a mailed and 

 felled mass of many species, of which the Papyrus, Pistia, 

 Stratiotcs, etc., form a part. Steamers have their wheels choked, 

 and even large and powerful ones are sometimes caught and kept 

 helpless among the weeds. Another numerous class of plants 

 which may be termed vegetable enemies are those which arc 

 possessed of slinging properties. The most familiar example of 

 this kind is the common nettle (Urtica dii-ica), everywhere 

 abundant, but particularly near human habitations, or on waste 

 ground of their former sites. The stinging apparatus is a hair 

 Avith a sharp point, which breaks off and pours the venom, purmic 

 acid, into the skin. Notwithstanding this peculiarity it is a useful 

 plant. Young tops of it are good as a vegetable for making 

 souii. Pigs and fowls are fed on it. The seed yields a sjjecies 

 of oil, and the whole plant is said to be a stimulant ia paralysis. 

 There are other species of the same genus, the stem of which is 

 more severe than that of the common nettle. One of these is 

 Urtica stimulans-Java, the smart'of which lasts 2-1 hours, and even 

 produces fever. Still worse is "Urtica Urentissima" — the 

 Devil's leaf — of which the pain lasts 12 months, and sometimes 

 proves fatal. A very lovely tree in Australia — " Laportea 

 Miroidies" — has large and beautiful dark green leaves, twelve 

 to fifteen inches long, which sting so severely as to be dangerous 

 to horses. It is said that even the common fig leaf produces 

 irritation. Pi-obably the worst enemies of all to mankind are 



