STINGING NETTLE AND FIG FAMILY. 237 



Urticaceae. 



The Stinging N^ettle and Fig Family. 



This is a large order, with about 1500 species of 

 108 genera in 8 tribes. In South Africa there are 10 

 genera in 3 tribes. The flowers are mostly unisexual, 

 either monoecious or dioecious ; but while members may 

 be very different in appearance, as a nettle is from a 

 mulberry and fig tree, yet the structure of the flowers are 

 so closely in agreement that they must be united, though 

 arranged in different tribes. Many species are provided 

 with stinging hairs. These, on close examination, will 

 be seen to be pointed cells, with a bulbous base, 

 within which is the irritating fluid. When the point 

 enters a pore of the skin, it breaks off, and fluid is 

 injected by the pressure. As it is too minute in 

 quantity to be analyzed, it is impossible to say what 

 its exact nature is. 



Urti'ca. — If we take the common perennial nettle, 

 U. dioi'ca, naturalized from Europe, it will be seen that 

 the male flowers (all on one plant) have a calyx of 

 four sepals with four stamens. These have their 

 filaments curled inwards in bud, so that as soon as 

 the sepals separate, they spring up and curl outwards, 

 flinging the pollen into the air, by the filaments being 

 under a great state of tension while they were kept 

 down by the sepals. 



The female flowers on separate plants have also 



