LEAF DIVISION. 



89 



its ancestral forms we 



more strongly 

 characterized by this condition (Fig. 448). 

 When the teeth and their sinuses are all 



connected in such a way that the margin 

 represents a wavy Hue, the latter is called 

 Kepand or Undulate, or Sinuate (Fig. 

 450). When a leaf is so deeply toothed 

 that the sinuses reach well toward t!ie 



middle portion (Figs. 451, 452, 453) the 

 term Lobed is substituted for those above 

 defined. When the division, by a sharp 

 sinns, extends more than half way to the 

 middle, yet not very near to the midrib, it 

 is called Cleft (Fig. 454A). When reach- 

 ing almost to the midrib (Fig. 454) or to 

 the base in case of a digitate leaf (Fig. 

 455), it is called Parted, and when all the 

 way, Divided i^Fi&s. 45G and 40D). The 

 divided leaf is, however, not the same a« 

 tJie compound leaf, inasmuch as the separ- 

 ation of its blade into distinct leaflets is 

 not complete, as our preceding description 

 calls for. The cleft, parted or divided 

 leaf, is either rinnatitid (Figs. 454, 4G3a, 

 ^c) or i'aimatifid (Figs. 455 and 456), ac- 

 cording to the character of its venation. 

 In all forms of lobed, cleft, parted or 

 divided leaves, it is necessary that the de- 

 tailed characters of the lobes and of the 

 sinuses should be specified. The lobe may 

 be acute, while the sinus is rounded (Fig. 

 453), or the reverse may be true (Fig. 451), 

 or both may be acute or both obtuse (Fig. 

 452). The sinuses as well as the lobes fre- 

 quently possess definite and characteris- 

 tic outlines, indicated by terms such as 

 have already been defined in connection 

 with the leaf. When the teeth and sin- 

 uses are outlined by straight lines and 

 sharp terminations, as though notched out 

 by a pair of scissors, the margin is said to 

 be Incised (Fig. 454a). When the divis- 

 ions and sinuses are long and narrow in 

 addition to being incised, it is called La- 

 ciniate (Fig. 45G), When the margin of a 

 leaf is turned downward or backward or 

 rolled backward, it is said to be Revolute. 

 Ordinarily the revolution is very slight 

 (Fig. 457), but occasionally, particularly 

 upon drying, it will be found extreme, 

 each half of the leaf forming a roll, the 

 two meeting back of the midrib (Fig. 458). 

 Before proceeding to speak of the forms 

 of compound leaves, it should be stated 

 that when one of the terms above defined 



(and the snmo is generally true of descnp- 

 tive terms tised in other parts of the work) 

 tcnninntos in tlio ending ate or otd. it 

 sometimes indicnfos that the condition 

 tends toward but does not quite n\TcIi that 

 UMiued by the term to which the ending is 

 appended. For example, triangulate 



^■?\**'*^ 



^^50. 



F.«V52, 



means inclining toward triangular. The 

 student will also note that between nearly 

 all the forms of leaves and the character-s 

 indicated by the terms above defined, 

 there are intermediate forms connecting 

 them with others. Inasmuch as it is 

 necessary in description for such forms to 

 be indicated, the method is resorted to of 



