Ill 



ANATOMY STUDY OF THE SHOOT 



2 5 





EXPT. 17. If a specimen of a plant can be obtained, which has been 

 attacked by the Dodder, it should be examined. Note 

 (i) How the Dodder climbs round the host, 

 (ii) How the suckers are produced. 



Climbing Plants. Plants climb over the shoulders of 

 their weaker brethren for two reasons ; (a) because their shoots 

 are far too weak to sup- 

 port their own weight, 

 and (b) to expose their 

 leaves to light. Climbing 

 plants present four divi- 

 sions, viz. : (i) Those 

 which climb by the aid of 

 rootlets, as the Ivy. (2) By 

 the use of hooks, as the 

 Bramble and the Yellow 

 Bedstraw. (3) By twining 

 stems, as the Convolvulus 

 and the Hop. (4) By 

 sensitive organs which 

 come in contact with any 

 structure and clasp it, as 

 the Clematis and the 

 Vine. 



Rootlet-Climbers.- 

 The Ivy climbs by means 

 of adventitious roots 

 which are produced from 

 the stem. When these 

 come in contact with a 

 wall or the bark of a tree 

 they give out a fluid, which 

 by drying up causes the 

 stem to adhere to the 



support. The rootlets are produced on the shady side of the 

 stem, and in older stems may not all be fixed to the support, but 

 may be "dried up, forming shaggy beards (Fig. 22). 



Hook-Climbers. The Bramble is able to support itself by 

 weaving its way through the trees which grow in its neighbour- 

 hood. It is able to do this because it produces hooks, by the aid 



FIG. 22. Ivy climbing up a wall. 

 R = Aerial roots. 



