280 



PRACTICAL BOTANY 



In general, plants which rise above the soil and into the air 

 must be supported, and must secure water from some source. 



The climbing vines 

 which are dependent 

 upon other plants are 

 supported by plant 

 tissue, though it is 

 not their own. Most 

 vines procure their 

 supply of water from 

 the soil and transport 

 it by means of their 

 own vascular tissues. 

 Fibrovascular tissue 

 makes possible the 

 upright position and 

 is essential, as is also 

 the absorbent and an- 

 choring root system, 

 alike to the fields of 

 upright grain and to 

 the forests. 



260. The fern plant: 

 asexual reproduction. 

 On the undersides of 

 the fronds or leaves 

 of most common ferns 

 there may at times be 

 found small brown- 

 ish dots (sori) com- 

 posed of sporangia. 

 These dots may each 

 FIG. 232. Leaflets from four kinds of ferns be covered by a shield- 

 In the different specimens the sporangia are at a, ^6 Outgrowth from 

 the indusium at *, and the false indusium at/.t. t } le epidermis (the 

 A, bracken fern; B, shield fern; C, spleenwort; . , r v 



and D, the maidenhair fern indusiuni) (Fig. 231), 



