334 



COMMON WEEDS 



S. simplex is another fairly common species resem- 

 bling the above, but with simple instead of branched 

 flowering stems, and often having narrow floating 

 leaves. 



Club-rush : "Bulrush," Reed-mace (Typha latifolia L.), 

 is a common water plant, with dark, rich brown spikes, 

 in shape somewhat like a lamp brush. The plant, with 

 its tall stems, is common in ponds and ditches, and on 

 the margins of lakes and rivers: it needs no further 

 description. 



LEMNACE^: 



Duckweed (Lemna minor L.). This is a familiar 

 palish green minute plant which is often seen com- 

 pletely covering 

 the surface of 

 small ponds. It 

 is abundant in 

 ditches and back- 

 waters of many 

 rivers and streams, 

 and is trouble- 

 some in watercress 

 beds. Each plant 

 floats on the water, 

 and consists of one 



or two flattened scale-like " fronds " an eighth of an inch 

 or so in diameter (Fig. 96). From the under part a 

 delicate root about J to i inch long dips into the 

 water. Very minute unisexual flowers arise on the 

 " fronds," and these produce seeds which propagate 

 the plant. Multiplication, however, goes on most 

 rapidly by vegetative budding off of young fronds, 

 which become disconnected from the parent and then 

 carry on an independent life, the process being repeated. 



FIG. 96. Lesser Duckweed (Lemna minor L.), 

 nat size. 



