130 Bulletin Jard. Bot. Buitenzorg, Série III, Vol. V. Livr. 2. 



It does not seem probable that Elaeis forms a rare exception. It is too 

 closely related to the Cocos palms to stand as an isolated case. We may 

 briefly summarize the stages in development of the oil palm leaf: 



Summary, 



1). The youiig leaf arises as a hook or blunt protubérance from the 



growing région. 

 2). Growth in height and width as well as in a circle goes on rapidly. 

 3). The lamina is deliminated from the pétiole and base by: 



(a) an horizontal furrow in the juvénile leaf (lanceolate leaf). 



(b) a vertical furrow in the pinnate leaf. 



4). Leaflets and segments owe their origin to individual 'Anlagen' within 



the young leaf blade. 

 5). Thèse 'Anlagen' maintain their individuality. 

 6). Development of the leaflets goes on within the lamina, before there 



is any outward indication of their présence. 

 7). Only definite parts of the lamina contribute to the formation of thèse 



leaflets — the rest form the envelope ('Haut') surrounding thèse leaflets. 

 8). Splitting of the leaflets occurs when they are within the enveloping 



tissue. 

 9). Formation of an epidermis in the leaflets foUows immediately upon 



splitting. 

 10). Growth of the leaflets against the envelope gives an outward 



appearance of swellings ("Wiilste" of Naumann). 

 11). Further pressure causes the tissue to rupture between developing 



leaflets (slits of VON MOHL and NAUMANN). 

 12). Leaflets shift their plane of growth. 

 13). Leaflets are for a time sac-like structures, then through growth and 



mutual pressure they become elongated and flattened. 

 14) The strip at the edge — the remains of the original lamina, persists and 



it is stretched to give an awn-like appearance to the tip of the leaflet. 

 15). Juvénile unsegmented leaves arise like fuUy segmented leaves. The 



plane of the 'Anlagen' is horizontal like in fan palms, 

 16). Transition from juvénile to mature leaf is accompanied by shifting 



of the horizontal plane to the vertical. 

 17). The number of leaflets in the mature palm is many times that of 



the young palm. 

 18). About 60 leaves in various stages of development are found in 



a five year old tree On the basis of observations of the number 



of leaves unfolded by an oil palm per year, it takes from 2'/2 to 



3 years for a leaf to fully develop, 

 19). The leaf sheath is a conspicuous and persistent organ originating 



soon after the leaf is deliminated. 



