BUDS AND LEAF ARRANGEMENT. 51 
dicotyledons, e.g., willow, oak, rose, apple, and cherry, display 
five-ranked or quincuncial (2) phyllotaxis (fig. 9). Here there 
are five orthostichies and five leaves in the cycle, which makes 
two turns round the stem. An eight-ranked (2) case may be 
seen in the holly, while the other divergences chiefly occur in 
cases where the leaves are much crowded. The house-leek, for 
example, presents the thirteen-ranked (,°;) arrangement. It 
frequently happens that irregularities are brought about from 
twisting of the stem and other causes, In the elm and beech, 
for instance, the two ranks of leaves are not exactly opposite each 
other, but are nearer together on the under than on the upper 
side of the branch. Here also we get a bilateral arrangement, 
z.e., the leaves are all approximately in the same plane ; hence 
it becomes possible to distinguish between upper and lower sur- 
faces in the branch. This also is caused by displacement of 
parts. 
We now come to a consideration of the kinds of leaf. These 
are generally taken to be four in number :— 
1. Foliage (euphyllary) leaves. 
2. Scale (cataphyllary) leaves. 
3. Bracts (hypsophyllary) leaves. 
4. Floral leaves. 
These will be described in the following chapters, 
