FORM AND STRUCTURE 
MARGINAL INDENTATIONS. 
A distinction is made between indentations that are shallow 
and those that are deep. Of shallow indentations the fol- 
lowing forms prevail in the leaves of deciduous trees : 
Serrate, saw-toothed, with sharp teeth which incline toward 
the apex ; distinguished as fine and coarse. (Fig. 27.) 
Bi-serrate, doubly serrate, with two sets of teeth one upon 
the other. (Fig. 28.) 
WN ID 
Nis \lhp Ni ‘ 
SUN » Hh CX 
a Se Ai NAN 
Fics. 27. 28. 20. 30. 31. 32. 33. 34. 
Dentate, toothed with outwardly projecting teeth; distin- 
guished as fine and coarse. (Fig. 29.) 
Crenate, scalloped, the teeth broad and rounded. (Fig. 30.) 
Undulate, when the margin forms a wavy line. (Fig. 31.) 
Sinuate, deeply wavy. (Fig. 32.) 
Repand, margin like that of an opened umbrella. (Fig. 33.) 
Spinose, margin spiny, (Fig. 34.) 
The common forms of deeply indented margins found in 
the leaves of trees are Lobed and Cleft. 
Lobed, when the indentations extend nearly half-way to the 
midrib or base, and the segments or sinuses or both may 
be either rounded or acute. The Oak and the Maple 
leaves are examples. 
Cleft, when the sinuses are deep, narrow, and acute. 
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