GROWTH AND WORK OF PLANTS 



" walking" fern travels in a similar way but it is the long narrow 

 leaf which is decumbent. The tip of the leaf strikes the ground 

 and organizes a stem which develops roots and new leaves. 



SPECIALIZED STEMS. 



77. Root-stocks.* These are subterranean stems. They 

 may be long and extend for a considerable distance in the ground 

 as in the mandrake, false Solomon's seal, many grasses, the 

 bracken fern and sensitive fern; or the stem may be short and 



thick like the underground stem 

 of the wake robin (Trillium). 

 Such underground stems are 

 called root-stocks. Most of 

 them, as in the case of the 

 mandrake, false Solomon's 

 seal, wake robin and grasses, 

 have erect stems which arise 

 as branches from the root- 

 stock and bear the flowers and 

 foliage leaves, while scale 

 leaves are borne on the sub- 

 terranean stem.-]- The root- 

 stocks of the bracken fern and 

 sensitive fern do not bear aerial 

 branches, but the large leaves 

 'which arise from the subter- 

 ranean stern have stout, long, leaf stalks which serve to lift 

 them up into the air and light. The root-stocks of Iris are 

 irregularly club-shaped, with prominent concentric rings and 

 stout, fleshy roots. Branching of the root-stock takes place 

 near the upper end. These branches arise in the axils of old 

 leaves and first appear as conical buds. In plants a few years 



* Rhizomes, also called burrowing stems. 



j"Grasses with subterranean stems (root-stocks) are in some descriptive 

 works said to be "stoloniferous." But this is not in accordance with the 

 Strict use of the term stolon since it does not apply to subterranean stems. 



Fig. 46. 

 Root-stock of iris. 



