46 NATURE-STUDY REVIEW 



eminently well. A bulbous swelling at the base doubtless serves 

 structurally as a sort of buttressing support. The persistant 

 crescent shaped scars where the fronds have separated from the 

 trunk make a pleasing pattern on the gray bark. 



Now, the crest of leaves is truly the crown of this kingly plant. 

 I cannot trust myself to expatiate upon its beauty as my enthusi- 

 asm might lead me to use language that would sound extravagant 

 and over-sentimental! So I will restrict myself to a description 

 of its mechanical structure and the perfect adaptation of structure 

 to function. 



In the first place, let us consider the individual leaf, frond or 

 "penca" as it is called by the Spanish-speaking people. One 

 notices first that it is pinnate, that is, long strips of leaf are borne 

 along two sides of a strong midrib or stem. This type affords a 

 maximum amount of surface to the sunlight with a minimum 

 resistance to the wind. Each leaf, often 15 to 20 feet long and 

 four to six feet broad, would afford a big resistance to the winds if 

 it were entire. Obviously, if such were the case, either the leaf 

 must split into shreds, like the banana, or the entire leaf be torn 

 away, or perhaps the tree itself be broken off. Certainly, the 

 slender stem of the coco palm could never carry such an expanse 

 of sail if its resistance to the wind were not reduced by every 

 possible device. 



Now, in addition to the leaf surface being cut into strips thru 

 which the wind may pass harmlessly, we find that these strips are 

 attached to the midrib as a V-shaped fold (figure 1). This makes 

 for strength and at the same time flexibility. It permits any 

 amount of lateral movement but provides for a measure of vertical 

 stability. Thus the strips may wave and sway in the breezes 

 or fold close in a storm and offer almost no resistance to the air 

 current. 



The midrib itself might well excite the admiration of a structural 

 engineer. Broad and clasping at the base, it half encircles the 

 trunk, grasping the latter by the crescent shaped horns of its 

 expanded base (figure 2) . Its attachment to the trunk aside from 

 this is really slight. The vascular bundles continue from the 

 trunk into the leaf but when the leaf is old and these give way 

 there is nothing more to hold them in place and they come loose 

 and drop off without any wrench or tear and leave no wound to 



