IN THE TROPICAL GARDEN. 265 



only the smothering of the trees can eradicate 

 them entirely. The others live by perfecting their 

 flowers and seeds very quickly, so that when the 

 parent is destoyed the children are ready to come 

 to the front at every opportunity. Like so many 

 weeds all over the world, they have a thousand 

 contrivances for scattering their seed. The Ruellia 

 tuberosa generally comes to the front in dry 

 weather, when it produces its handsome blue 

 flowers and capsules. These capsules are so 

 sensitive to moisture that when the rains fall 

 they open suddenly and shoot the seeds to some 

 distance. Other plants have hooked capsules, by 

 means of which they cling to the fur of animals 

 and are often carried away for miles ; while a third 

 class provide plumes to their seeds, which enable 

 them to float upon the wind. But, above every- 

 thing else, the grasses are most rampant. One of 

 the commonest in gardens is the bahama grass 

 (Cynodon dactylon), which is almost the only kind 

 suitable for lawns. This, however, is unable to 

 endure much moisture, and therefore when the 

 heavy rains fall, unless the soil is very light and 

 well-drained, it suffers greatly. Then, it is gradually 

 ousted by the Paspalum compressum, which 

 spreads its leaves almost flat, and continually 

 extends outward, smothering everything in its 



