ROOTS OF CRYPTOGAMS. 



117 



their allies) do not differ essentially from those of Phaenogums ; 

 in most cases, however, the terminal growth, except in the order 

 LycopodiaceiE, is from a single apical cell instead of a group of 

 cells. The apical cell produces not only the tissue of the body 

 of the root as it extends in length, but gives rise also to the 

 superficial cells at the extremity which constitute the root-cap. 

 Lateral roots start from the interior layer of the cortical paren- 

 chyma, and not from the pericambium (see 345). 



354. The fibro- vascular bundles are concentric (see 313), as 

 indeed they are in the 



stems of most of these 

 plants ; that is, the bast 

 part surrounds the wood 

 part, as if with a sheath, 

 even where the latter part 

 is rudimentary. There is 

 a tendency in the root, less 

 marked than in the stem, 

 to the production of scle- 

 rotic cells of a dark color. 



The roots of the higher 

 cryptogams do not materi- 

 ally increase in thickness 

 after they are first formed. 



355. Proper roots are 

 not found in Muscineae (the 

 mosses and hepatics) ; the 

 absorbing organs here are 

 more strictly root-hairs. 

 These arise as papilla; from 

 the outer cells, and speedily 

 develop into tubular and 

 frequently complex bodies. 

 They often become 

 branched in a remarkable 

 manner, twisting and coil- 

 ing around one another like the fibres in a thread. They, as 

 well as the somewhat simpler organs of the same nature, found 

 in the^ Thallophytes (such as Algo3, and the like), are termed 

 Rhizoids. 



FIG. 97. Seedling of Cucurbit* Pepo, showing the main root, side roots, and root- 

 hairs. (Sachs. ) 



