34 



CLIMBING PLANTS 



As a rule the sub-aerial foliaged axis is of 

 appreciable length. It may be erect, as in the 

 Sunflower, or it may be extended horizontally 

 over the surface of the soil (fig. 55). The 

 "runners" of the Strawberry are creeping 

 stems which have long internodes and produce 

 tuft-like shoots and adventitious roots at the 

 nodes (fig. 54). Between erect and prostrate 

 stems various transitional stages occur. 



CLIMBING PLANTS. 

 A prostrate trailing plant usually has long, 

 slender stems which call in the assistance of 

 the soil to bear the weight of the branches and 

 leaves. Another group of plants — climbers — 

 also require external support ; they rise above 

 the soil and lean against, or fix themselves to, 

 other plants, rocks, walls, etc. Like the 

 majority of prostrate plants, climbers have 

 slender stems, usually with long internodes — 

 in fact, a climbing plant may become prostrate 

 if it finds no external object up which it can 

 climb (fig. 55). Climbing plants may be 

 ranged for the present Tinder four heads : 

 root - climbers, twiners, irritable - climbers, 

 scramblers. 



(i.) Root - Climbers. — The Ivy ascends by 

 means of numerous aerial adventitious roots, 

 which are • given off by the stem and serve to 

 fix it to the supporting object. 



(ii.) l?wining Plants are those possessing 

 stems which twist round the supporting objects. 

 In most cases the twining stem twines in a 

 definite direction ; for example, the Bindweed 

 {Convolvulus) cUmbs in a left-handed spiral, as 

 is shown in fig. 56 ; whereas the stems of the 

 Hop and Honeysuckle ascend in a right- 

 handed spiral. The differences between these 

 Cmwivuius twiners and the following class of climbing 

 (AS'De P^^"*^^ ^"^6 "^ot sasy to explain in this ele- 

 nert.) ' mcntary work, but it may be generally stated 



Fig. 

 S6. 

 Twining 



