124 ROBERT TRACY JACKSON ON 



Palms. Amongst palms many species present interesting features of localized stages 

 in development. I have studied the development of seedling palms of thirty-seven species, 

 and from puljlishcd figures of von Martins and others know something of the early chai-ac- 

 ters of about forty-five species, distributed tlirough twenty-eight genera. Seedlings of all 

 species have simple, early seed-leaves, and these are always one of two types. The first 

 and most primitive type of seed-leaf is elongate, lanceolate, or oval, ternunating more or 

 less acutely, and with a longer or shorter rachis, usually long. This type is seen in Latania 

 (PL 23, fig. 9i), Corypha (PL 23, fig. 104), Cocos (PL 23, fig. 102), Phoenix (PL 23, 

 figs. loo. 103, lO.lal and many other genera. The second type of nepionic or seed-leaf 

 is similar to the lirst, except that it is distally cleft. It is characteristic of ChrysaUdocarpus 

 (PL 23, fig. 95), Kentia (PL 23, fig. 9G), Caryota (PL 23, fig. 98), and of many other 

 genera. Very .young specimens of genera which have distally cleft leaves or exce2)tional 

 individuals show a transient distal fusion of the apices of the leaf, as in Kentia (PL 22, 

 fig. 96), demonstrating that the cleft type is oidy a modification of the first or entire type. 

 In some types, as Stevensonla grandlfolla J. Dune. (Phoenicojjhor^nn secheUancm H. 

 WendL), which have distally cleft leaves, the first leaves are entire, the cleft character 

 appearing later (third leaf of the specimen in hand). This is a further demonstration of 

 the primitive nature of the entire type. In some eases the acuminate tips of seed-leaves 

 may l)e modified by distal truncation, as in ArciKjd xacchai-ifera Labill. and Caryota 

 cumlngii IjodiA. (C »re».s Blanco.) (PL 23, fig. 98) . 



A fossil species from the Cretaceous (Laramie), Oreodoxites 23licafus Lesq., closely 

 resembles the form of tlie more primitive type of seed-leaf, and hardly differs, except in 

 its greater size, from the young leaf of Corypha (PL 23, fig. 104). Other fossil palms 

 from the Cretaceous and Tertiary belong to genera the yoiuig of which is characterized by 

 the entire type of leaf. 



In Latania covDiiersoji'u J. F. Gniel. (L. t>orho»ica Lam.), the seed-leaf is ovate, lan- 

 ceolate (PL 23, fig. 94); during growth the later leaves l)ecome relatively broader, mitil, 

 by distal tension, splits take })lace (PL 23. fig. 9;i), and in tlie adult the leaf is a ([uite 

 broad, fan-leaf type. The development of other fan-leaf palms, as Sabal, Washingtonia, 

 Chamaerops, and Ra])his, is similar to that of fjatania. The angle of divergence of the 

 rays varies directly with the relative length of the laehis and the amount of leaf-tissue 

 formed. 



In Phoenix ca/tarienxis llort. the first seed-leaf (PL 23, fig. 100) is elongate, lanceo- 

 late. The first leaves of PhocJtix rupkola T. Anders, are similar; in later added growth 

 the leaves, while retaining their simple outline, become relatively broader, with an elongate 

 rachis, as shown in leaf 1, PL 23, figs. 103, 103a. During growth, as new leaves are 

 added, the rachis elongates, the leaf-tissue on the sides becomes relatively reduced, and 



