I 



1 



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907] 



STOKEY— ROOTS OF LYCOPODIUM PITHYOIDES 



59 



The 



ii 



mm 



(I), who stated that they were characteristic of erect dichotomous 

 forms. Strasburger (ii) described the more obvious features 

 of the ''inner roots" of L, Selago, and gave a list of about twenty 

 species characterized by their presence. All the species noted are 

 mcrfLbers of the Selago group except L. Phlegmaria. In none of 

 the species described have the ''inner roots" attained a development 

 comparable to that in L. pithyoides. Few have been studied m 

 sufficient detail to afford a basis for comparison. Strasburger 

 records L. Selago as showing eight roots in a cross-section taken 5"^"^ 



above the base of the stem. 



phi 



and L. verticillatum with fifteen "inner roots." Fig. 2 shows a cross- 

 section of Z. pithyoideSj taken lo-is^"" above the base of the stem, 

 m which fifty-two roots were found. The extraordinary development 

 of these roots is no doubt an important factor in giving the stem its 

 characteristic stoutness and rigidity. 



The root prime rdia usually appear within 2-5'""' of the tip of the 

 stem, but occasionally there will be none within 5-10^^" of the tip. 



primordium shown in ^g. j and fig 



mm 



stem 



cm 



from 

 high. The vascular cylinder 



of the stem was still in the promeristem stage. 



The roots of L. pithyoides show four distinct initial regions for 

 the plerome, periblem, dermatogen, and calyptrogen. The plerome 

 arises from an initial region consisting probably of only one initial 



cell 



impo 



of initials, but such preparations as that shown in fig. 5 indicate a 

 single initial; it is possible, however, that there are several, as in the 

 forms studied by Bruchmann (3). The periblcm initial region 

 consists of several layers forming a well-defined although not sharply 

 differentiated region. There is a well-defined one-layered dermatogen 

 which gives rise to the epidermal cells and trichoblasts. 



The trichomes arise from definite cells which are cut off by curved 

 oblique walls from the original epidermal cells a short distance back 



ih 



With 



mal cells and trichoblasts, the latter come to have the appearance of 

 wedge-shaped cells. The outer wall rounds out and a papilla appears 

 which rapidly elongates into a slender, rather thick-walled, persistent 



