STEMS. 
least possible surface is 
presented by a plant of 
given bulk,—that is, in 
the form of a sphere or an 
egg-shaped mass. ‘This, 
above ground, corresponds 
to the corm or solid bulb 
of the crocus and the Indian 
turnip among underground 
stems. Other cactuses are 
more or less cylindrical or 
prismatic, others still con- 
sist of flattened joints, but 
all agree in offering much 
less surface to the sun and 
air than is exposed by an 
ordinary leafy plant. 
© 73. Leaf-like Stems. — 
The flattened stems of some 
kinds of cactus are suffi- 
ciently like fleshy leaves 
a, 
49 
Fic. 35.— A Six-weeks’-old Potato Plant 
grown from the Seed. 
b, upper branches, cut off ; d, cotyledons ; 
e, underground stems, springing from buds 
in the axils of the cotyledons; /, g, tubers 
developed from ends of underground stems 
or from axils of scales borne upon them ; 
h, roots. 
to pass for leaves among people who are not botanists, but 
; LE 
Fig. 36.— I, Bulb of Hyacinth. II, the 
same split lengthwise. 
I 
Ce 
there are a good many cases 
in which the stem takes on a 
strikingly leaf-like form. The 
common asparagus sends up in 
spring shoots that bear large 
seales which are really reduced 
leaves. Later in the season, 
what seem lke thread-like 
leaves cover the much- 
branched mature plant, but 
these green threads are actually 
minute branches, which per- 
