542 LXXVII. PALM^. [Borassus. 



the radius, but may also be observed in a horizontal section. In vertical 

 sections a portion of the vascular bundles will be found to run straight 

 downward, but they are crossed by other bundles at oblique angles. The 

 latter are those portions which bend outward towards the base of the leaf or 

 the lower part of the stem. In transverse sections some bundles may gene- 

 rally be noticed, cut through in a slanting, not horizontal direction ; these 

 were cut across in their outward course towards the circumference of the 

 tree. Again, the structure of each bundle is different in its upper and lower 

 part : in its upper part it contains all three classes of elementary organs 

 enumerated above, vessels, fibres, and cells; whereas the lower part is almost 

 entirely composed of fibres. This will explain the different composition 

 of the vascular bundles near the centre, and the circumference of the stem., 

 The stem of many Palms has a distinct rind composed of thick-waUed cells, 

 and inside of it the outer vascular bundles (consisting mainly of thick- 

 walled fibres) are sometimes nearly confluent/, but never entirely so. But 

 though the outer stratum is harder, there is no distinct bark that can be 

 stripped off, and no continuous confluent cambium layer as in Dicotyledons 

 and Conifers. Nor are there any annual rings in the wood of Palms. 

 After the stem has once attained a certain size, it does not materially 

 increase in thickness, though it sometimes swells out in an irregular 

 manner. 



As regards the surface, one group of Palms has smooth and shining 

 stems, annulate with raised rings, which are not quite horizontal, but 

 slightly and alternately incHned to opposite sides. These rings are the 

 scars of fallen leaves, and according to the length of the joint or internode, 

 they are at greater or less distances from each other. The Rattans {Cala- 

 mus) and the Betel Palm (Areea) are instances of this group. In another 

 group {CJiamcBropa, Borassus, Coeos, Phoenix) the surface of the stem is 

 rough with the persistent base of the petioles, and in this group the inter- 

 nodes are always short, and the leaves and scars of petioles are arranged 

 around the stem in a series of close spirals. It wUl be readily understood 

 that in the Palms of the second class the leaves always stand close together, 

 forming a dense tuft at the end of the stem, while in those of t^e first 

 group the leaves stand at some distance, often covering a considerable 

 length of the stem (Calamus). 



The leaves of seedlings are always undivided ; those which are formed 

 at a later period are generally either pinnately or palmately divided, the 

 pinnae or segments being linear or lanceolate, mostly folded longitudinally 

 with numerous and parallel nerves. The segments of palmatifid leaves are 

 frequently bifid, those of pinnately divided leaves are either entire or 

 irregularly lobed (WalUahia, Caryota, and allied genera), and in that case 

 the edge or outline of the leaf runs partly with the nerves, partly across 

 at an oblique angle, a portion of the outline appearing dentate by the pro- 

 jecting ends of the nerves. The petiole is always broad-based, and gene- 

 rally amplexicaul or sheathing. 



The inflorescence is terminal in some Palms {Corypha, Metroxylon), but 

 lateral in most cases, either in the axils of existing or fallen leaves. It is 

 generally a panicle enclosed in bud by large sheathing bracts (spathes). 



