396 POPULAR SCIENCE MONTHLY. 



conditions so that the whole plant is dwarfed.* The above remarks apply 

 to a frond or rather to the midrib of a palm when looked at in cross- 

 section. When considered in cross-section the plumose fronds vary in 

 a striking manner. The leaflets are arranged upon the midrib so that 

 they may be in two rows or in four or six or more rows — half on one 



Fig. 12. Diagrammatic Representation of the Positions'of Palm Fronds, half of the 



Head being shown. 



side and half on the opposite side of the petiole. Seen in cross-section 

 these latter take on one of the forms shown in the following diagram or 

 one of many other combinations. These differences between fronds de- 

 pend to a great extent on the manner in which the leaflets are attached 

 to the midrib. For example, the leaflets may lie in a single plane 

 growing straight out from the opposite sides of the midrib or they may 

 lie in two, four, six or eight planes that meet along the midrib. 



Fig. 13. Diagrams of Cross-sections of Palm Fronds, showing the ARRANGEiiENT of the 



Leaflets. 



The fronds have, in addition to these peculiarities, certain habits 

 due to the shapes of the midrib. A midrib that is broad at the base 

 and continues relatively broad to the end is compelled to remain, as to 

 cross-section, in a horizontal position; but if a midrib is broad at the 

 base and gets rapidly narrower toward the end it cannot maintain itself 

 in a horizontal position, but twists a fourth of the way round and at 

 the end lies on edge. Sometimes this twisting goes to such an extent 

 that the frond is quite inverted. The cross-sections of the midribs of 

 palm fronds are characteristics to which but little attention seems to 

 have been given by botanists. 



Every palm leaf begins its life at the apex of the trunk — the newest 



* Since observing this peculiarity of palm fronds, I have frequently seen 

 something of the same kind in the great 'deadenings' of the South and South- 

 west. Many species of trees arc readily recognized at a distance by the atti- 

 tudes of the dead and broken limbs: the limbs of the black oak stand up 

 nearly straight; those of the black-jack hang down and curl under, while 

 those of the post oak are full of 'elbows.' 



