GENEBAL MORPHOLOGY OP THE PLANT 33 



of lateral branching in which we have a continuous axis giving 

 off lateral branches ; but it differs in the fact that here the 

 apparent primary axis consists of a succession of secondary axes. 



In sympodial branching, again, the sympodium may be either 

 formed of the fork-branches of the same side (left or right) of 

 successive dichotomies [fig- 43, A, I, I, I) ; or it may consist 

 alternately of the left and right fork-branches or bifurcations 

 {fig. 43, B, /, r, 7, r). In the former case it is called helicoid 

 diclioiomy ; in the latter, scorpioid dichotomy. 



Of the lateral branching there are also two forms, the race- 

 mose or monoxjodial and the cymosc. In the first the primary 



Fis. 45. Fig. 46. 



Fig. 45. Leaf of Bryophyllum cdlycimtm with buds on its margins. Fig. 



46. A portion of the leaf of Ornithogalum thyrsoideum, showing buds, 

 6, &, &, on its surface. 



axis continues to develop upwards and gives off acropetally 

 lateral branches from axillary buds ; which also give off lateral 

 branches in a similar manner. The main axis here constitutes 

 a monopodium, as it forms a single foot or podium for the 

 branches. In the second form the lateral axes at an early age 

 develop much more vigorously than the primary axis, and each 

 gives rise to other lateral branches in a similar way {fig. 

 44, A). In some plants, by the partial or total suppression of 

 the terminal bud, and the subsequent vigorous growth of the 

 closely arranged lateral buds forming two shoots apparently 

 radiating from a common point, as if caused by the division of 

 the terminal bud, as in true dichotomous branching, an apparent 

 but false dichotomy is produced. This suppression of the 

 terminal bud may occur naturally, as in the Lilac (fig. 39), or 

 accidentally from frost or other injury. 



When two buds arise just behind the apex and two branches 

 are consequently developed there, as in fig. 44, A, the branch 

 system is called a dichasium ; when there are more than two a 

 polychasiwm results. The branch system in these cases may be 

 called polypodial. When, on the other hand, only one branch 



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