igig] 



WA TERM A N—ROO T SYS TEMS 



39 



decaying plant parts. Great care was taken in excavating these 

 specimens, which are simply typical of a number of cases found, and 

 there can be no question that in every case the roots stopped in the 

 decaying plant parts as figured. 



Artemisia caudata. — This species germinates freely on the open 

 dunes, and also in the edge of the forested sections. It is described 

 by Gray as not perennial, but the character of the mature speci- 

 mens found on the dunes would indicate that there at least it has a 

 perennial habit. Two series of plants are shown, one grown in 

 pure sand (fig. lo), the other in sand containing some admixture 



,-i^ 



Fig. io 



Fig. II 



Figs, io, ii. — Artemtsia caudata: fig. lo, which grew in pure dune sand, showing 

 stumps only of long laterals; fig. ii, of apparently same ages as in fig. lo, but in sand 

 containing some humus; laterals very short. 



of humus (fig. ii). In the former may be observed the stubs of the 

 characteristic laterals, which in mature specimens extend 20-30 ft. 

 No attempt has been made to show in the figure the full extent 

 of these laterals, but rather their relation to each other and to the 

 taproot. In pure sand this species shows some of the asymmetry 

 of Prunus pumila, but the causes are not so evident. In some 

 specimens very long laterals develop almost on the surface of the 

 sand, and are so shallow that they are often exposed and killed 

 by the blowing away of the upper dry sand layer. In other speci- 

 mens it is one or more of the deep seated laterals which shows 



