54 THE PALM-STEM: 



of the leaf in breadth, and thus the leaf occupies so much 

 the smaller arc of the circumference of the stem, the older 

 the latter grows ; while in other cases, the converse may 

 take place, the leaf grow broader than the stem, and the 

 two borders of the leaf overlap. As examples of such 

 plants, in which the originally perfectly amplexicaul leaf 

 only partly embraces the stem when full-grown, Aletris 

 fragrans and Dracaena Draco are, in particular, brought 

 forward ; in the former, the full-grown leaf embraces f of 

 the stem, in the latter, the leaves at the apex of the year- 

 ling-shoot are still perfectly amplexicaul, while on older 

 stems the cicatrices of the leaves only extend i round 

 the stem. This proportionately greater expansion of the 

 stem in thickness is connected, in Dracaena, with an 

 abbreviation of the already perfectly formed internodes, 

 as is apparent in a comparison of the length of the inter- 

 nodes of the yearling- shoot with those of the old stem, 

 and as even a superficial examination of the growth of 

 Dracaena shows ; for the rapid growth of the yearling- 

 shoot does not by any means correspond to a propor- 

 tionate elongation of the whole plant (p. 22). A necessary 

 consequence of this change of the relative proportion of 

 the breadth of the leaf to the thickness of the stem is, a 

 change of the original position of the vascular bundles in 

 the interior of the stem. So long as the young leaf sur- 

 rounds the stem and lies in the middle of the bud, the 

 vascular bundles (corresponding to the lower portions of 

 the complete vascular bundles) run from the whole peri- 

 phery of the stem, in a radial direction, towards the base 

 of the leaf. As the bud unfolds, the internode per- 

 fected beneath the leaf to which it belongs, and the leaf 

 proceeds outwards from the centre of the bud towards 

 the periphery of the stem, the upper portions of the vas- 

 cular bundles are developed, which, in consequence of this 

 outward movement of the leaf, assume a curve from the 

 centre of the stem towards the exterior, and run out in 

 the direction of a radius. Since, however, during the 

 completion of the leaf, the proportion of its breadth to 



