THE LEAF 19 
like that of an ordinary trunk, and which supports the leaf blades 
and the fruit in much the same way as does a trunk (Fig. 66). 
The main stem is thick and short, with a convex top to which 
the leaf bases are attached. The slender fruiting stalk pushes 
up in the center of the elongated leaf bases and is supported by 
them (Fig. 67). 
In grasses the younger part of the stem has a soft growing 
region just above the attachment of each leaf. This growing 
region is so soft and weak 
that it could not, by itself, 
support the part of the 
plant above it. The leaf 
base has the form of a 
long, slender tube which 
surrounds and supports 
the stem and enables it to 
bear its load (Fig. 68). 
Tendrils. The climbing 
plants have slender stems 
which do not possess suf- 
ficient strength to hold 
themselves erect. Such 
plants catch on to other 
objects, particularly other 
plants, and thus make use 
of the strength of these other objects to support them. This 
enables them to grow up into the sunlight without expending 
the material which would be necessary to build a strong trunk. 
Tendrils are one of the means by which plants hold on to other 
objects. Tendrils are long, slender structures which curl around 
objects with which they come in contact. They are frequently, 
but by no means always, modified leaves. Any part of a leaf 
may be modified in this manner. Tendrils may be modified 
whole leaves, petioles (Fig. 69), leaflets as in the garden pea 
(Pisum sativum) (Fig. 69), tips of leaves (Fig. 69), or modified 
stipules (Fig. 69). 
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I'1qg. 67. Cross section of the false trunk of 
the banana plant, showing small flowering 
stalk surrounded by leaf bases. (x 4) 
