56 SOUTH AFRICAN BOTANY 
stem. The phellogen of the periderm when formed 
joius on to the lenticel cambium. 
It is important to notice that no cork cells are formed 
in a lenticel, and so air can pass freely into the stem. 
They can be made out by the naked eye as small specks 
or lines on young twigs. 
32. Branching.—There are two chief forms of branch- 
ing. (1) Dichotomous BRaNncuHING, and (2) MonoroDIAL 
a; cm 
eS 
OCOD os 
a ey eee eure oat 4 
2 Fae 
CBS, oo 
SE OS? ~ cor 
Fic. 37.—Lenticel. 
c. Cutin. e. Epidermis. ck. Cork. p. Phellogen. cor. Cortex. em. 
¥ Complementary cells, 
BraNcHiInG., In dichotomous branching (fig. 88) the 
growing point divides into two equal parts, then the 
growing points of these two branches do the same, so 
that we get a series of bifurcations. This type of branch- 
ing is chiefly met with in the mosses and ferns. In 
monopodial branching there is always a persisting main 
axis, the Monopopium, which gives off lateral branches. 
There are two kinds of monopodial branching, (a) INDEFI- 
NITE or RAcEMOSE, and (6) DEFINITE or Cymosz. If 
the monopodium continues to grow, giving off lateral 
branches one after the other, we have indefinite or race- 
mose branching. If after giving off alateral branch the 
monopodium ceases to grow and the branching is con- 
