ROOTS. Henne dice ce 1% 
Rocts are those organs of plants which are usually 
found underground. 
Recalling the work done on germination of seeds 
and the results obtained in exp. 17, under stems, give 
different origins of roots. Those roots which develop 
directly from stems are called adventitious roots. Study 
those found on a corn stem. Do they have a definite point 
of origin on the stem? Of what use are they? The cut 
ends of shoots of a geranium or wandering-jew may be 
put into jars of water at home and thus the development 
of roots studied. 
Roots may grow in air, water, or soil. Those which 
grow in air are called aerial roots; those in water, water 
roots, and those in soil, subterranean roots. 
As an example of aerial roots study those of an ivy 
climbing on a wall. (This study may be carried on most 
advantageously outside the laboratory.) What is the 
function of these roots? Do they branch from the stem 
at any definite place? (See Bergen—Foundations of Bot- 
any, page 306.) 
Water roots may be found on plants growing in the 
aquarium in the laboratory. Study these roots. Do they 
branch? Are they attached to the stems at any definite 
point? Ask the instructor for a few specimens of 
Lemna. Lay one of the plants onto a slide and cut the 
roots off near the leaf-like portion of the plant and study 
them under a hand lens and the low power of the micro- 
