Stem Branching types

The pattern of arrangement of branches on stem is called branching. it provides proper place for each branch. Unbranched stem is called Caudex (= Columnar). Caudex is unbranched stout stem with scars and remnants of fallen leaves and crown of leaves e.g., palms; Culm is that caudex in which nodes and internodes are very well distinct (jointed stem). Nodes are solid and intemodes hollow. Sum culms are called wooden grasses e.g., Bamboos. 

Branching is of two types :

(ii Dichotomous : The growing point divides into two to form two similar branches e.g. Liver worts, Dictyota, Asclepias, Hyphaena. 

(ii) Lateral : Axillary buds form a lateral branch and apical bud remains non dividing. Branches develop from Iateral buds in two manners. 

(a) Racemose or Monopodiai Branching. Apical bud of the main stem grows indefinetly so that the main axis continues from base to the tip. This unbranched axis is calied monopodial axis ortrunk Lateral branches do not compete with the main axis. They develop acropetally (oldest towards the base and youngest towards the growing point). it gives pyramidal (excurrent) shape. e.g. Eucalyptus,Mustard, Casuarina, Pinus. 

(b) Cymose or sympodial Branching. Apical bud of the main stem has limited growth. it is then either used up or modified into a fiower/thom/tendrii. Further growth of axis is continued by one, two or more branches arising from axillary buds. Thus main axis is not produced by the activity of main apicai

bud but by many axillary buds, hence called sympodiai axis (sympodium). Accordingly, cymose branching is of three 

types ; 

(1) Uniparous or Monochasial Cyme. The terminal bud stops its activity or get modified into the flowerltendril/thorn. Further growth of the axis is continued by one axillary branch an'sing lateraliy from axillary bud. Soon its bud also stops growth and the process is repeated. The successive branches develop on either both the sides alternately (scorpioid, e.g., Grapevine) or on one side only (helicoid. e.g., Saraca). 

(2) Biparous or Dichasial Cyme. After the inactivity of the growing point of the parent axis, further growth is continued by two lateral (axillary) branches: Axis is multipodial, e.g., Viscum, Carissa, Mirabis, Datura. 

(3) Multiparous or Polychasial Cyme. After the inactivity of the growing point of the parent axis,further gorwth is continued by more than two 'laterai branches. Axis iis multipodial, e-g., Euphorbia helioscopia, E. tirucalli, Croton