DEVELOPMENT OF THE MEMBERS OF A BRANCH-SYSTEM. 
179 
or cymose manner; and the cymose development may be either apparently 
dichotomous (or even apparently polytomous) or sympodial. 
(a) A racemose system occurs v^hen the monopodial mother-shoot continues 
to develope more strongly than all the lateral shoots, and when the lateral shoots 
of each successive order behave in the same manner in respect to their mother- 
shoot. This occurs very clearly, for instance, in the stems of most Conifers 
(especially Pinus, Araucari'a, &c.) and in the compound leaves of Umbellifers. 
(b) The cymose development of a monopodial system, or a Cy7?ie^ depends on 
the fact that each lateral shoot begins from an early period to grow more strongly, 
and in consequence of this, also branches more copiously than the mother-shoot, 
the growth of which then usually soon ceases. Two principal forms of Cyme 
may be distinguished, according as a pseud- axis (sympodium) is formed or not. 
(a) When two, three, or more lateral shoots arise beneath the growing end of 
each shoot, which develope 
in different directions more 
strongly than their mother- 
shoot, the growth of which 
soon ceases, a false Dicho- 
tomy (or Trichotomy, or 
Polytomy) arises. Fig. 135 
represents the formation of 
a false dichotomy; the shoot 
/ produces the shoots //', 
ir\ originally weaker, but 
soon growing more strong- 
ly, while the growth of / 
ceases; the same takes place 
with Iir, and nr. False 
dichotomies of this kind, which occur abundantly in the inflorescences of Phanero- 
gams, are termed by Schimper Dichasia. But instead of two lateral branches 
growing out in opposite directions, three or more shoots standing in a true 
or spurious whorl may develope more strongly than their mother-shoot, and 
thus arises an umbellate system, such as is developed in a typical manner in the 
inflorescences of our native Euphorbias; a system of this kind may be called a 
Cymose Umbel. 
(ß) The sympodial development of an originally monopodial system occurs 
when one lateral shoot always developes with greater vigour than its mother- 
shoot, as is shown in Fig. 136, A, where the lateral shoot 2, 2 grows more 
strongly than the part 2, i of its mother-shoot, and so on. Usually the portions 
of all the shoots which lie below their lateral branches develope more strongly 
than the terminal portions, as is indicated in the figure by the thicker lines ; the 
terminal portions (indicated by thin lines) often die off early; the thicker basal 
portions of the different ramifications which proceed from one another then com- 
monly place themselves in a straight line, and have the appearance of a connected 
whole ; like a primary shoot to which the terminal portions of each separate order 
of shoots are attached as if they were lateral branches. The apparent primary 
N 2 
FIG. 135. • 
Diagram of a false dichotomy (dichasium) ; the numerals indicate the order 
of development of the shoots of the system. 
