94 



ORGANOGRAPHY. 



i^i^f. 183. Fig. 184. 



Fig. 183. Dicotyledo- 

 nous stem, with a 

 woody twining plant 

 around it. 



Fig. 184. Monocotyle- 

 donous stem, encircled 

 by a woody twiner. 



thus, in the Doum 

 are formed, so that 



sive swellings produced, which exhibit a 

 corresponding- increase of the diameter of 

 the stem. Such a comparison shows, in a 

 very striking and conclusive manner, the 

 characteristic peculiarities of the growth 

 of exogenous and endogenous stems. 



In a Palm stem, as we have seen {fig. 

 178,1), there are commonly no branches, 

 such stems having no power of forming 

 lateral buds from which they are produced. 

 These plants therefore grow simply by the 

 development of a terminal bud, which 

 Avhen it unfolds covers the summit with a 

 plume of foliage. Such stems are accordingly 

 nearly of the same diameter below as above, 

 and thus form a cylindrical column. ' In 

 such trees the destruction of the terminal 

 bud necessarily leads to the death of the 

 plant, as it is then deprived of all mode of 

 increase. In some endogenous trees how- 

 ever more than one bud is developed: 

 Palm of Egypt (Ht/phcene thebaica), two 

 the stem is forked above (fig. 185); each 



Fig. 185. 



Fig. ISj. The Doum Palm of Egypt Ulyphuene thebaica). 



