CH. II 



MORPHOLOGY 



4. Hair-structures. These may grow from all .parts of the 

 plant and may be short, or long and silky. All hair structures 

 agree in being developed from the epidermis or skin-like 

 coverings of the plant. Some hair-structures serve to keep off 

 unwelcome guests, like ants ; others again, like those of the 

 horse chestnut, secrete or form a kind of glue to protect the 

 young buds from cold ; while 

 some, like the dandelion, take 

 part in scattering the seeds. 



Organs. From a physio- 

 logical standpoint the parts 

 of a plant are spoken of as 

 its organs. An organ is a 

 structure which is able to 

 perform some special work, 

 e.g., the root is an organ be- 

 cause it fixes the plant to the 

 soil. 



EXPT. i. Obtain a nearly 

 full-grown Wallflower plant, and 

 examine it. "Observe 



(i) The shoot is erect and 

 branched, and the older part is 

 hard and woody. The upper 

 part of the shoot is green, and 

 the lower part of it is covered 

 with a pale- brown bark. 



(ii) That the shoot can be 

 divided into stem and leaf the 

 leaves being outgrowths of the 

 stem. 



(iii) That the stem branches, 

 and the branches rise from the 

 space between the stem and 

 leaves. The space between the 

 leaf and stem is called the axil 

 of the leaf (Fig. 3). 



(iv) That the leaves are green, thin, veined, and lance-shaped. 



(v) The shoot is hairy, the hairs lying very close to the surface. Pass 

 the leaf through the ringers and note what the hairs feel like. 



(vi) That the main root is nearly colourless and tapers from the point 

 where it joins the stem to its apex. Springing from the main root will 

 be seen a very large number of secondary roots, or root branches, which 

 help to fix the plant to the soil. 



FIG. 2. Wallflower Plant. 



