40 



BOTANICAL GAZETTE 



[JULY 



extreme elongation. The superficial laterals show marked paral- 

 lelism with the upper surface of the sand, even in plants growing 

 on slopes; where the laterals join the main root at different angles, 

 they are acute on the upper side and correspondingly obtuse on 

 the lower. The position of these laterals seems to be on the rela- 

 tively constant plane separating the upper layer of dry sand from 

 the moist sand which constitutes the remainder of the substratum. 

 In general the system is characterized by extreme shortness of 

 taproot, but occasionally the taproot becomes very prominent. 





-n 



Fig. 12 Fig. 13 



Figs. 12, 13.— Fig. 12, Campanula rotundifolia: a, normal root habit; b, young 

 plants on exposed edge of horizontal marly layer; fig. 13, seedlings of Lathyrus mari- 

 tima, showing remains of seed and root tubercles. 



Artemisia resembles Amnwphila in the reduction in length of roots 

 in the presence of organic matter or humous layers, and its roots are 

 not attracted by decaying plant parts. It will be noted in fig. 1 1 

 that the laterals of this series, which grew in sand mixed with humus, 

 are finer, more branched, and with none of the very long laterals 

 of the pure sand specimens. The fact that the roots are not 

 attracted by decaying plant parts was distinctly shown in one case 

 where a mature plant with laterals up to 6 ft. in length was growing 

 near a decaying log. One lateral passed a few inches below the 

 log in a zone of leaching, bent first away, then toward the log. 



