180 MYSTERIES OF THE FLOWERS 



the St. John's-worts, Depford pink, and smaller 

 Solomon's seal are generally, but not always, self- 

 fertilised. 



The smallest flowering plant in the world, the 

 duckweed, or Lemna, follows the same plan, and is 

 most interesting to study under the microscope. 

 You will find in stagnant pools myriads of these 

 tiny plants, forming a green crust 

 upon the surface. The plant, con- 

 sisting of one or two leaves, about 

 one-fourth of an inch in length and a 

 little less in width, floats upon the 

 water, sending down one or several 

 threadlike roots, an inch long, each 

 terminated with a pointed sheath. 

 The plant grows' by lateral branch- 

 ing, and toward autumn the leaves 

 separate from each other, form sepa- 

 rate plants and sink to the bottom of the pool, to 

 rise again in the spring, larger and more mature. 

 In the summer the flowers, such as they are, appear 

 upon the surface or at the edge of the plant. They 

 are monoecious flowers, reduced to the lowest terms, 

 for they consist of one or two stamens and one 

 pistil, of the form shown in the sketch. 



These organs are in such close proximity that 

 they fertilise each other, and produce true seeds. 



DUCKWEED 



