XIV 



L YCOPODINE^E 



475 



.s^ 



augurated by a broadening of the apex of the root, which is 

 followed by a forking of the plerome and a subsequent division 

 of the other histogenic tissues. 



The structure of the mature root ^ in L. clavatiun, L. 

 alpinum, and most species examined, is much like the stem. 

 The hexarch to decarch fibrovascular cylinder is radial in 

 structure, the xylem plates often 

 united at the centre, so that 

 in cross-section they present a 

 more or less regular stellate 

 form. In L. selago and L. in- 

 undatuju, according to Russow,^ 

 the xylem is diarch and the two 

 masses united into a single one, 

 which is crescent-shaped in sec- 

 tion, with the phloem occupying 

 the space between the extremi- 

 ties. As in the stem the primary 

 tracheids are narrow annular 

 and spiral ones, and the large 

 secondary ones scalariform. 



Gemmcs 



Special bulblets or gemmae 

 are formed regularly in a number 

 of species of Lycopodiiun, and 

 have been the subject of several 

 special investigations.^ These 

 in L. lucididum (Fig. 248, A. k) 

 are flattened, heart - shaped 

 structures composed of several 

 thickened fleshy leaves, and 

 formed apparently in the axils 



Fig. 248. — A, End of a shoot of Lycopodiutn 

 lucididmn (Michx.), with gemma: (k) and 

 sporangia (j/). X2; B, a single bulblet, 

 X4; C, germinating bulblet of L. selago 

 (after Cramer), X4 ; r, the primary root. 



of somewhat modified stem 



leaves, from which they readily separate when fully grown. The 

 axillary origin of the bulblets is only apparent ; they are really, 

 so far as can be determined, similar in origin to the ordinary 



^ Russow (1), p. 150 ; Van Tieghem, " Recherches sur la symmetrie de la structure 

 dans les Plantes vasculaires" [Ann. Sc. nat., ser. 5, No. xiii.). 



- Russow ( I ). ■' Hegelmaier (i) ; Strasburger (7) ; Cramer (i). 



