BOOTS OF CRYPTOGAMS. 



117 



their allies) do not differ essentialljr from those of Phsenogams ; 

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

 Lj'copodiaceiE, is from a single apical cell instead of a group of 

 cells. The apical cell produces not onl}- 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. Tlie flbro-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 

 ci-yptogams do not materi- 

 ally increase in thickness 

 after they are first foi'med. 



355. Proper roots are 

 not found in Muscineas (the 

 mosses and hepatics) ; the 

 absorbing organs here are 

 more strictl}' root-hairs. 

 These arise as papillae from 

 the outer cells, and speedil}' 

 develop into tubular and 

 frequenth- complex bodies. 

 They often become 

 branched in a remarkable 

 manner, twisting and coil- 

 ing around one another like the fibres in a thread. The3', as 

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

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

 Mhizoids. 



m 



Fig. 97. Seedling of Cucurbita Pepo, showing tlie main root, siJe roots, and root- 

 hairs. (Sachs. ) 



