18 



BOTANY 



PART I 





15 Ah) is illustrated by the Selaginellas. Such an apparent main 

 axis (.<;, s) is termed, in accordance Avith its origin, a SYMPODiuar. On 



the other hand, in the 

 monopodial system 

 two or even several 

 lateral branches may 

 develop more strongly 

 than the main axis, 

 and so simulate true 



DICHOTOMY or POLY- 



TOMY. Such mono- 

 podial forms of branch- 

 ing are referred to as 



FALSE DICHOTOMY 



(Fig. 15 Bi\) or false 

 POLYTOMY, as the case 

 may be. A good ex- 

 ample of false dicho- 

 tomy may be seen in 

 the Mistletoe (Fiscum 

 album). If, however, 

 a lateral branch so ex- 

 ceeds the main axis in 

 development, pushing 

 the apex of the latter 

 to one side, that it 

 seems ultimately to 

 become a prolongation 

 of the axis itself, a 

 sympodium is again 

 formed (Fig. 15 Bh). 

 This is what occurs in 

 many of our forest 

 trees, e.g. the Lime 

 and Beech ; in both of 

 these trees the ter- 

 minal buds of each 

 year's growth die, and 

 the prolongation of 

 the stem, in the follow- 

 ing spring, is continued 

 by a strong lateral bud, so that in a short time its sympodial origin 

 is no longer recognisable. In many rhizomes, on the other hand, 

 the sympodial nature of the axis can be easily distinguished ; as, 

 for example, in the rhizome of Polt/r/onatum muliifloruiii (Fig. 23), 

 in which, every year, the terminal bud gives rise to an aerial shoot. 



Fio. 10. — Cryptomeria japonica, Don. (From L. Beissner, Hand- 

 huch tier Nailelholzkunde. Greatly reduced.) 



