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288 BOTANICAL GAZETTE [october 



relation to departing traces. Leaves frequently develop without 

 corresponding roots. This early vacillating condition is replaced 

 by regularity after the establishment of a central parenchyma, 

 and a single root takes its departure from the stele just below the 

 attachment of the leaf trace. Subsequently there is a second 

 period of irregularity when either one or two roots are detached 

 from the stele with each leaf. 



In his studies of the apical regions of Todea Barbara, Bower (i) 

 states: "The roots take their origin from a single cell of the endo- 

 dermis which is situated opposite a xylem strand." In all cases 

 observed in the young stem the root apical cell originated in the 

 pericycle (figs. 45, 48). The initial cell enlarges, and, following a 

 few radial divisions, a single apical cell develops which is quite 

 variable in shape, but very early organizes into a three-sided 

 pyramidal cell (fig. 47) . Bower (i) further states that of a number 

 of root apices examined in Todea Barbara "not one showed a clearly 

 marked single apical cell. Some, however, showed somewhat 

 irregular arrangements, and in some it appeared uncertain whether 

 the meristem be referable to three or four initial cells. In the 



majority of the roots observed it is clearly referable to four initi; 

 cells, separated from each other by the four principal walls. 



?> 



In 



many 









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plants, and not a single instance of four initials was observed. 

 There were a few cases which showed some variation from the 

 pyramidal three-sided cell, with the divisions occurring unevenly. 

 The segments from the apical cell are usually very large and do not 

 divide immediately, resulting in a meristematic group resembling 

 in longitudinal view a cluster of three or four initials. These, 

 however, have always been referable in the root to a single initial 

 which was prevailingly of the triangular-pyramidal variety. Thus 

 the coaxial type described by Bower (i) was not found in any 

 of the root meristems of the early sporophytes. 



The outer cortical cells of the primary root are usually the 

 first to develop the sclerenchyma thickenings which later become 

 so conspicuous a feature of the stem cortex. From the primary 

 root they are extended to the adjoining cells of the stem in which 



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