342 EXPERIMENTS rflTH PLANTS 



duction of flowers and fruit. Land -plants growing in\ 

 unusually rnoist situations run to stem and leaf, and 

 produce flowers and fruit sparingly: on the 

 contrary, when growing in unusually dry places, 

 the same plants produce relatively more abun- 

 dant flowers and fruit than usual. Such water- 

 plants as are descended from land -plants are, 

 as a rule, unable to flower or fruit under water 

 (Water Plantain, Arrowhead, Hippuris, etc.). 

 Gardeners induce plants to flower abundantly 

 by digging a trench around the base of the 

 trunk, and thereby cutting off numerous active 

 roots: another method is to simply lay the 

 roots bare. Cacti which are allowed to become 

 somewhat dry and shrunken bear more freely. 



Bending and breaking the branches of fruit 

 trees, which results in partially cutting off the 

 water supply, is practiced for the purpose 

 of causing trees to fruit. It also tends to 

 make the fruit sweeter and of higher 

 flavor. Fruit grown in the mountains 

 (where it is dryer and the light stronger) 

 is usually superior in these respects. Over- 

 irrigation has a tendency to produce 

 watery fruit which is neither very sweet 

 nor highly flavored. 1 197. Leaves of i>7n- 



delion drawn on 



By knowing just when and how much to SJSSa^S )^^ 



in a saturated at- 

 1 See pages 318 and 319. mosphere. 



