436 BOTANICAL GAZETTE [may 



* 



successive years. Decapitated plants are not killed, but, having 

 no means of renewing the apical meristem, they cease to grow or 



divide. Fig. 21 represents such a decapitated 



stem in three successive years, the upright por- 



20 I ; ; j tion shortened each year by the equivalent of a 



a bed 



Lb 



21 



year's growth. Whether such a stem will finally 

 become altogether horizontal, I do not yet know, 

 nor have I yet been able to discover the cause of 



Figs. 20 21.— ^he re gul ar change in direction from upright to 

 Fig. 20, diagram horizontal. Observations in the field seem to 

 representing posi- s h ow fa^ root contraction is not the determining 



successiv^yeTr" cause ( stem ^ps decapitated in 1 9 1 5 were found to 



fig. 21, diagram be dead in the summer of 19 19). 



representing posi- Some interesting data can also be gathered in 



tated planfthree regard l ° the behavior of the roots - TheSe > aS 



successive years. m many other species of Lycopodium whose 



tips are erect or sloping (6, 7, 9), do not pass 

 straight out through the cortex, but turn downward. In L. Selago 

 these roots "arising at the apex pass obliquely, then directly 

 down through the middle cortex and only appear at the outside 

 beneath the soil" (6). The 



same 



originate at the apex, but 



begin, at some distance behind the apex; how far behind is 

 not clear. They rarely form within the first year's growth. 

 Apparently they increase in number in the older parts of the 



stem; but as small roots might easily be 



in 



freehand sections, I am not quite certain that new roots may 

 form in parts of the stem as old as five or six years. These 

 roots, in the upright part of the stem, remain small, usually less 

 than 6 mm. in length. As they do not emerge to the outside 

 until in a part of the stem at least six or seven vears old, it is 



evident that they must be in a dormant or slowly growing condition 

 within the cortex for as many as two to five years. The downward 

 growth in the cortex is not very great, the distance between the 

 junction with the central cylinder and the point of emergence to 

 the outside varying from 6 to 15 mm. Reaching the soil, they 



grow rapidly, quicklv reaching a length of several inches. 



