54 



ENDOGENOUS OR MONOCOTYLEDONOTJS STEM. 



Exogens. Occasionally, at the upper part of a palm-stem there is an 

 appearance of zones, but it does not continue throughout the stem. 

 From the absence of concentric circles, the age of a Palm cannot be 

 estimated hi the same way as an exogenous tree. The elongation, 



however, of each species of Palm 

 is pretty regular, and by it an 

 opinion may be formed of the 

 age. The rings on the surface 

 of the stem are not indicative of 

 yearly growth. 



99. In Palms, there is in gen- 

 eral no provision for lateral buds, 

 and no branches are formed. 

 Hence, destroying the central 

 bud will kill the tree. In some 

 Palms> however, as the Doom 

 palm of Egypt (Cucifera thebaica\ 

 the stem divides in a forked or 

 dichotomous (/#, two ways, 

 and Ttpvu, I cut,) manner. 

 Gardner, in his travels in Brazil, 

 noticed a Palm in which the cen- 

 tre bud had been destroyed, and 

 two side ones had been produced, 

 so as to- give it a forked appear- 

 ance. Other plants with endo- 

 genous stems, also produce lateral 

 buds, In fig. 115, 2, there is 

 a representation of such a stem, 

 in the case of the Screw-pine, 

 (Pandanus odoratissimus), and examples are seen in Grasses, as the 

 Bamboo, in Asparagus, Asphodels, and Dracaenas. In these cases, the 

 stem is conical, like that of Exogens, and the destruction of the ter- 

 minal bud is not necessarily followed by the death of the plant. The 

 development of lateral buds is accompanied often by an increased 

 diameter of the stem. A Draeasna in the Canary Islands, has a hollow 

 stem capable of holding several men; and the fact of its living in this 

 state, is marked by Jussieu as an argument against the strict endoge- 

 nous formation ; for, if the centre were the youngest and newest part, 

 its destruction would put an end to the existence of the tree, in the 



Fig. 115. Two endogenous or monocotyledonous trees, belonging- to two different families. 

 1. Cocos nucifera, or coco-nut, belonging to the Palm family. 2. Pandanus odoratissimus, or 

 screw-pine, belonging to Pandanacea?. The first has a simple unbranched stem, with a cluster 

 of leaves at the summit; the second has a branched stem, with numerous leafy clusters, and 

 peculiar aerial roots, proceeding from different parts of the stem. Two human figures are given 

 to indicate the height of the trees. 



