STEMS 59 
Caladium, this stem-like character is less evident. The 
potato is an excellent example of the short and much- 
thickened underground stem known as a tuber. 
It may be seen from Fig. 33 that the potatoes are none 
of them borne on true roots, 
but only on subterranean 
branches, which are stouter 
and more cylindrical than 
most of the roots. The 
“eyes” which they bear are 
rudimentary leaves and 
buds. 
Bulbs, whether coated like 
those of the onion or the 
hyacinth (Fig. 34), or scaly 
like those of the lily, are 
merely very short and stout 
underground stems, covered 
with closely crowded scales 
or layers which represent 
leaves or the basis of leaves 
(Fig. 35). 
The variously modified 
forms of underground stems 
just discussed illustrate in a 
marked way the storage of 
nourishment during the 
winter (or the rainless sea- 
son, as the case may be) to secure rapid growth during 
the active season. It is interesting to notice that nearly 
all of the early flowering herbs in temperate climates, like 
the crocus, the snowdrop, the spring-beauty, the tulip, and 
Fic. 82. Roots, Rootstocks, 
and Leaves of Iris. 
