Ill 



CLIMBING PLANTS 



Many plants have stems which grow to a considerable length, and 

 which are at the same time too weak to support the plants in the 

 erect position. A considerable number of tliese show no tendency 

 to assume an upward direction, but simply trail along the sur- 

 face of the ground, often producing root fibres at their nodes to 

 give them a firmer hold on the soil and to absorb additional sup- 

 plies of water and mineral food. Some, however, grow in the midst 

 of the shrubs and tall herbage of thickets and hedgerows, or in 

 some other position in which it becomes necessary to strive for a due 

 proportion of hght, and such plants would stand but a small chance 

 in the struggle for existence if they did not develop some means of 

 securing a favourable position among their competitors. 



These latter are collectively spoken of as chmbing plants ; but 

 it is interesting to note that in their seedhng stage they are all 

 erect, and it is only after they reach a certain height that they com- 

 mence to assume some definite habit by which they obtain the 

 necessary support, or to develop special organs by which they can 

 cling to objects near them. 



Some cUmbers produce no special organs for the purpose of 

 fastening themselves to smTOunding objects, but trust entirely to 

 the wandering and more or less zig-zag nature of their feeble stems, 

 and thus reach the open light merely by a process of interweaving, 

 as in the case of the Hedge Bedstraw {Galium mollugo). Others 

 adopt this same method of interweaving, but at the same time 

 develop some kind of appendages to give them additional supj)ort. 

 Thus, the Rough Water Bedstraw [G. uliginosum), which sometimes 

 reaches a height of four or five feet, has recui'ved bristles all along 

 its slender stem, and these serve as so many little hooks, holding 

 the plant securely on to the neighbouring rank herbage of the marsh 



