NO. 7 A NEW PAI.M FROM COCOS ISLAND COOK 1 3 



of Rooseveltia has a fibrous structure like other palms, the arrange- 

 ment of the fibers makes it possible for growth to continue, a hard 

 shell being formed by closely compacted stout fibers, but with finer 

 fibers outside, under a surface crust. The layer of large indurated 

 fibers is about 2 cm. thick, with the fibers about 2 mm. in diameter, as 

 shown in natural size at the right of plate 5 ; the layer of finer surface 

 fibers is about 4 mm. thick. The fibers of the interior of the trunk- 

 are only 1 mm. or less in diameter, separated by loose pith. Each of 

 the pith fibers has a large tubular channel on its mesial face, notably 

 larger than the channels of the thick fibers or those of the smaller fibers 

 near the surface. The finest fibers, delicate and filiform, are embedded" 

 in a light brownish corky stratum underlying a brittle surface crust, 

 less than 1 mm. thick. The exposed surface of the crust, though 

 appearing nearly smooth, is marked with fine longitudinal grooves, 

 rather irregular and indistinct, usually 2 to 4 mm. apart, as shown 

 at the left of plate 5. Where the surface is protected by crustaceous 

 lichens, or overlaid with fine roots of epiphytic plants, the "bark" 

 becomes thicker and more deeply fissured, leaving no doubt of a 

 gradual renewal taking place where the surface is exposed. 



The leaf-scars are difficult to detect on sections . from the lower 

 part of the trunk, but internodes 5-6 cm. long are indicated ; on the 

 fruiting section the internodes are reduced to 2.5 cm., the leaf-scars 

 longer than the intervening zones, often attaining 2 cm., the scars 

 not impressed or constricted, the surface somewhat uneven with 

 scattered granules or tubercles where the fibers are attached (see pis. 

 10 and 12). Much longer internodes are indicated by photographs of 

 Plcctis, probably attaining 12 to 15 cm. (see pis. 20 and 21). Two or 

 three consecutive joints bear inflorescences, with an interval of 3 or 

 4 barren joints before the inflorescences of the next season are 

 developed. 



N 



CHARACTERS OF THE LEAVES 



The leaf-crown of Rooseveltia, as shown in the photographs, is 

 more ample than that of Plcctis, and has a different aspect on account 

 of the longer rachis and the more numerous and longer pinnae, and 

 because the pinnae of Plcctis droop from the rachis in a gradual curve. 

 The rachis is held more erect or ascending in palms that stand in the 

 open, shown in plates 1 and 19, instead of spreading or drooping, as 

 in the more protected forest locations, plates 2 and 3. Although the 

 leaf-blade is notably longer than in Plcctis, about 4 m. instead of 3 m., 

 the petiole is much shorter, 10-15 cm. instead of 35-45 cm., and the 

 lowest pinnae are much closer together, only $-6 cm. apart to 12-14 cm. 



