MARGIN AND APEX. 27 
like a saw, with the teeth projecting forward. Such a mar- 
gin is said to be serrate, or, if the teeth are quite small, ser- 
rulate. When the teeth point neither forward nor back- 
ward, but outward, we call the margin dentate, or toothed; 
and if the teeth are quite small, denticulate. See Figs. 49, 
50, 51, &e. 
31. Some leaves are margined with rounded and blunt 
teeth, and we call them crenate (Fig. 52); or, if such teeth 
are very small, crenulate. 
32. In Figs. 18 and 50, you see that the teeth themselves 
are again toothed, an arrangement called doubly dentate. 
So we may find leaves doubly serrate or doubly crenate. 
Thus we have described seven modes or styles of border- 
ing. Several other modes are found described in the larger 
botanies. 
APEX. 
-OOMMON dh 
“WAL NY PSP 
Fig. 56. Apex of leaves: a, obcordate; 3, emarginate; v, retuse; d, truncate; 
, obtuse; 7, acute; g, mucronate; h, cuspidate; &, acuminate. 
Fig. 57. Bases of leaves: /, hastate; m, n, sagittate; 0, auriculate; p, cordate; 
7, Teniform. 
80. When is the margin serrate? When serrulate? How joes the den 
tate differ from the serrate ? 
81. What sort of teeth does the crenate imply? Crenulate? 
$2. Explain doubly dentate, &. 
