UNDERGROUND STEMS 



177 



Underground Stems. — The Potato, Onion, and Artichoke are 

 famihar examples of underground stems. Many of the plants 

 grown in the greenhouse and 

 on the lawn for decoration, 

 such as the Lilies, Hyacinth, 

 Tuhp, Crocus, etc., have un- 

 derground stems. This type 

 of stem is common among 

 plants with the vernal habit. 

 Many of our useful Grasses, 

 as Red Top, Kentucky and 

 Canada Blue Grass, Orchard 

 Grass, and others have peren- 

 nial subterranean stems from 

 which aerial stems are sent up 

 each year. Grasses of this 

 type hve many years and are 

 the Grasses which produce 

 our permanent pastures. 

 Grasses of this type are also 

 chosen for lawns, because their 

 spreading underground stems 

 produce a compact sod and 

 send up a thick aerial growth. 

 Quack Grass, Johnson Grass, 

 some Morning Glories, Poi- 

 son Ivy, and many other 

 weeds have underground 

 stems, and it is due to this 

 feature that such weeds are 

 hard to eradicate. Cutting 

 off the aerial stems of these 

 weeds does not kill the plant; 

 for the underground portion 

 still lives and is able to send 

 up more aerial stems. 



Underground stems are least adapted for displaying leaves and 

 bearing flowers, and they must either produce leaves and flower 

 stalks long enough to reach above ground or grow branches which 

 become aerial stems upon which the leaves, flowers, and fruit are 



Fig. 162. — Morning Glory twining 

 around a Corn stalk. 



