414 Pomona College Journal of Economic Botany 



appearance must be in direct correspondence with the more internal, or 

 last formed leaves. 



According to these views we may suppose that in the vegetative cone 

 of the trunk of a palm, the phenomena occurring in a primordial leaf are 

 repeated as many times as there are leaves in the crown. Tlie entire body of 

 a palm should, therefore, be considered as a sympodiuin or an aggregate of 

 several unities, each represented by one leaf furnished at its base with a 

 vital node, from whence descend the fibro-vascular bundles, which ultimately 

 end in corresponding roots. 



The incipient fil)ro-vas(Milar bundles descending from every newly formed 

 leaf should, therefore, from the beginning, be considered as containing the 

 elements of new roots and as corresponding to the first root issuing from the 

 node of a primordial leaf. Such descending bundles, if they were not 

 prevented by the continuous change of position of the leaves, as these 

 gradually expand, would penetrate gradually and vertically the central part 

 of the woody cylinder down to the roots; but as everybody knows, the new 

 leaves are, during their expan.sion, gradually transported towards the 

 periphery of the stem, and consequently the fibro-vascular bundles derived 

 from the bases of these leaves are obliged to follow them, and to take the 

 well-known course from the periphery towards the center of the woody 

 cylinder, from whence they can freely descend throughout its entire length 

 down to the base. Here, however, of necessity, the vascular bundles are 

 forced to bend again towards the periphery, because they need to be organ- 

 ically connected in one way or another, with the roots. This connection, 

 however, cannot be made with the old pre-existing roots, because these occupy 

 the central part of the base of the trunk, and because every new emission 

 of roots always takes place externally to and above the old ones. 



Generally it is believed that the new roots originate quite independently 

 of the vascular bundles of the central cylinder, but that a connection is 

 established later between the bundles of the roots and those of the stem.* 

 But my observations, however, confirm those of Meneghinit, who has demon- 

 strated that in Chamaerops hximilis "The fibro-vascular bundles of the roots 

 are direct continuations of those descending from the leaves and more 

 especially of those which being the last formed are peripheric;" and I will 

 add that the point of emission of a new root is, in consequence, pre-estal)- 

 lished by the position of its corresponding leaf. To strengthen this opinion 

 I would remark that, in cultivated palms, there is always a correlation 

 between certain leaves and certain determinate roots, so that if a root be 

 injured by disease, or is killed by other cause, the corresponding leaf also 

 sliows signs of decay, and vice-versa. It may, also, be observed that a new 

 root can never originate in direct correspondence to an old or dead leaf. 



*Drabble: On the Anatomy of the Roots of Palms, in Trans. Linn. Soc. London S'd 

 Ser. VI (1904), Botany, page 443. 



■\Meneghmi: Ricerche suUa struttura del caule delle piante Monocotiledoni (1836), 

 page 101, tab. VII. 6. 



