UNDERGROUND STEMS 177 
Underground Stems. — The Potato, Onion, and Artichoke are 
familiar examples of underground stems. Many of the plants 
grown in the greenhouse and 
on the lawn for decoration, 
such as the Lilies, Hyacinth, 
Tulip, 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 aérial stems are sent up 
each year. Grasses of this 
type live 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 aérial 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 aérial stems of these 
weeds does not kill the plant; 
for the underground portion 
still lives and is able to send 
up more aérial stems. 
Fic. 152. — Morning Glory twining 
around a Corn stalk. 
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 aérial stems upon which the leaves, flowers, and fruit are 
