6 



ESSENTIALS OF VEGETABLE PHARMACOGNOSY. 



i 



exceptions, at the point where the leaf 

 emerges from the stem and upon the up- 

 per side of the former. This point is 

 known as the leaf-axil. The portion of 

 the phytomer which gives origin to these 

 three structures is called its node (c). 

 The portion intervening between two 

 nodes is called the intcrnode (d)* The in- 

 ternode does not normally possess the 

 power of giving origin to new parts. The 

 branch is found, after development, not 

 to differ essentially from the stem, so 

 that a branch may be regarded as a lat- 

 eral stem, secondary, tertiary, and so on. 

 In noting hereafter the development of 

 the other parts of the plant out of those 

 here named, we shall frequently find the 

 latter so modified that we shall be unable 

 to recognize them by the ordinary meth- 

 ods of examination, and the relative posi- 

 tions which they occupy will prove an im- 

 portant guide. A correct understanding 

 of morphology requires, therefore, that we 

 keep in mind the following facts relating 

 to the intemode, node, leaf, branch and 

 superimposed phytomer. 



2. There is a definite and regular ar- 

 rangement as to position of the leaves 

 upon the stem in most cases. 



3. Several leaves and as many branches 

 may develop from one node. 



4. The branch normally develops in the 

 leaf-axil, and conversely a leaf, in some 

 form, is normally at the base of each 

 branch in its rudimentary condition. 



5. All growth developing in the leaf- 

 axil is a manifestation of the branch. 



6. All organs of the plant which we 

 consider, except the root, are constructed 

 of the above parts in some modified form, 

 or are appendages upon them. 



Certain necessary qualifications of these 

 statements can be made only when we 

 come to the study of the stem, and these 

 do not involve any failure to understand 

 correctly the principles of anthology. 



Before proceeding to consider the forms 

 of structural modification of the phyto- 

 mers in the development of the flower 

 certain important properties pertaining to 



them, in addition to their ability to mul- 

 tiply and grow as above indicated, should 

 receive attention in order that later a com- 

 parison of reproductive methods can be 

 instituted. It is found that if, in the case 

 of certain plants, a stem be laid prostrate 

 in the soil^ its connection with the parent 

 not destroyed (Fig. 2.), its nodes, in ad- 

 dition to producing branches (a), may de- 

 velop roots (b) similar in structure and 



function to those of the parent. If now 

 the phytomers be separated through some 

 portion of the internode, they will heal the 

 wound so produced by the formation of a 

 callus (c), continue to grow independently 

 and become plants similar to the parent. 

 Such a process, here of artificial produc- 

 tion, is of frequent natural occurrence and 

 is called Propagation. It is seen to be 



1. Any of them may remain more or purely vegetative, and may be defined as 



less undeveloped. 



the production by vegetative processes of 



