14 WINDOW AND PARLOR GARDENING 
Buds are formations of the stem; from these come leaves 
and branches and flowers. In deciduous plants the buds are 
very different and more complex than in evergreens, being pro- 
tected by recinous scales. 
All bulbs are merely buds composed of a number of more or 
less fleshy scales or leaves. ‘They serve to store up nutriment 
or for the purpose of propagation. 
Leaves serve to assimilate plant-food under the action of 
light and heat. ‘The under side of the leaf is covered with 
thousands of openings through which the carbonic acid of the 
air is absorbed. The leaves also serve as organs of evapora- 
tion. 
The green matter of the leaf is called chlorophyll, and can 
only be formed under the influence of sunlight; hence the 
yellowish or white leaves of plants accidentally growing in 
deep shade. As the leaf is one of the most important organs 
of the plant and absolutely necessary to growth and develop- 
ment, it is important always to keep the same clean and in a 
healthy state. Leaves are either simple, as in the Oleander, or 
compound as in the Mimosz, or sometimes absent and substi- 
tuted by broad and flattened leaf-stalks or petioles, as in many 
Acacias. 
The simple leaves are of many different forms ; the chief 
types are parallel-veined leaves, as in the Calla, and all lilies 
and netted-veined ones, as those of the Geranium. 
The shape differs considerably. Plate II. gives an idea of 
the most common types. The edge of a leaf is seldom entire. 
When only slightly cut, it is toothed or crenate; or, when 
wavy as that of the oak, undulate. According to the degree of 
incision it is called cut, lobed, cleft, parted, or divided; divided 
being the highest degree of incision. Next to these come com- 
