LEAVES 
Leaves are opposite (Fig, i), whorled, more than two spring- 
ing from the same level on the stem (Fig. 2), or otherwise, 
including alternate (Fig. 3), and from the root only (Fig. 4). 
The leaf may have a stalk of its own (leaf-stalk or petiole), it 
may grow directly on the stem or the branch (sessile), or may, 
at its base, envelop or clasp the stem or the branch (Fig. 11). 
The technical terms for these conditions are avoided, but will 
be found in the glossary at the end of the book. 
The leaf -stalks are set on the branches at varying angles so 
that no one leaf lies directly below the next one. This secures 
to each leaf the maximum amount of sunlight. Where the leaf- 
blades fall in line it will generally be found that it is because 
the stalks have become twisted. Thus Figs. 5 and 6 represent 
two branches from the same shrub, the one upright, the other 
inclined downward. The leaf-stalks in Fig. 6 leave the branch 
on the same planes as in Fig. 5, but the leaf -blades, by twisting 
of the stalks, have become parallel, doubtless because the 
greatest amount of sunlight is here thus obtained. This is 
made clear in the enlargement (Fig. 7). 
It is to be remembered, however, that in illustrating plants the 
leaves are often represented flattened out as they are in her- 
barium specimens. Recognition of these facts will aid in tell- 
ing a compound leaf, whose leaflets are on the same plane. 
A compound leaf is made up of leaflets or separate similar 
parts; for example, a Clover leaf (Fig. 8) is made up of three 
leaflets, a Poison Sumach leaf (Fig. 9) of seven to thirteen leaf- 
lets, in this case of seven. In the Clover and Sumach the leaf 
is once compounded; it may be more than once compounded, 
as in Early Meadow Parsnip (Fig. 10), in which it is twice com- 
pounded. When the leaflets rise from a common point, as in 
the Clover or Horse-chestnut, they are said to be palmate; if 
