66 A TEXT-BOOK OF BOTANY 
branches. In the tuber called Jerusalem artichoke, which is 
developed by the subterranean stems of a kind of sunflower, 
the nodes of the stem and the buds of branches are more 
conspicuous than in the potato. Tleshy roots, such as those 
of the sweet potato, should not be confused with tubers. 
(6) Bulbs.—In some plants the main stem is very short 
and is covered by numerous thickened, overlapping leaves 
or leaf bases (usually called scales), the whole structure 
being a bulb. Bulbs 
such as those of the 
lily, hyacinth, tulip, and 
onion are very familiar. 
In this case the food 
storage is chiefly in the 
scales. Scaly bulbs are 
those in which the scales 
overlap, but are not 
broad enough to enwrap 
those within, as the lly 
bulb (Fig. 65); coated 
bulbs are those in which 
Fre. 65.—Scaly bulh of white lily: A, exte. the broad scales com- 
rior view; B, longitudinal section, showing pletely enwrap those 
short stem and overlapping scales.—After Stier oa 
Bion within, as the bulbs 
of onions and_ tulips. 
Small bulbs, called bulblets, are borne by some plants on 
parts above ground; as, for example, the bulblets that ap- 
pear in the axils of the leaves of the tiger-lily and those that 
replace flower-buds in the common onion. ‘These bulblets, 
when planted, have the power of producing new plants, as 
do the subterranean bulbs. 
The above subterranean shoots, with their storage of 
reserve food, enable plants to put out their aerial parts with 
remarkable promptness and develop them with great 
rapidity. As an illustration of a situation in which this 
