6

THE PALM-STEM.

constituting the transitions to the other forms of stems, are found inDesmoneus, Rhapis flabelliformis, and Corypha frigida.

2. The Calamoid stem ( Caudex calamosus) resembles the cane-like, hut isdistinguished by the extraordinary length. The internodes are from two tosix feet long, thin, apparently cylindrical, but equally obeonical; the surfacesmooth, shining as if varnished; of a stony hardness. The substance is notfirmer at the periphery than in the middle; the vascular bundles are distri-buted almost uniformly throughout the whole stem; the woody mass ismoderately hard, exceedingly elastic, and tough; the external fibrous layeris very thin; the stony, hard epidermis splits off in scale-like pieces when thestem is bent. This form occurs only in Calamus ; the transition to the cane-like stem is through Desmoneus.

3. The Cylindrical ( Mauritia-Yikc ) stem is remarkable for its beautifullyregular uniformity and smooth, round form. The internodes are pretty longand cylindrical; the leaf-scars are narrow and do not form knot-like pro-jections ; the rind thin, not much affected by the action of the atmosphere,often clothed with spines. The internal structure is very strongly marked;almost the whole mass consists of a weak, lax, pith-like parenchyma, in whichlie vascular bundles of herbaceous softness. Firm woody vascular bundlesare only found at the periphery in a narrow circle; but on account of theirfrequently considerable thickness and hardness, they form an almost impene-trable layer. The external fibrous layer is mostly very thin. This formoccurs in Mauritia ( armata, vinifera), (Enocarpus [minor, &c.), Kunthia[montana), Astrocaryum (vulgare , &c.)

4 Cocos-like stem ( Caudex cocoides). This is thick, and somewhat irre-gularly knotted from the closely approximated, broad leaf-scars, and fre-quently shaggy with the vascular bundles of the fallen leaves and witheredleaf-sheaths; often very tall. The vascular bundles are distributed almostuniformly throughout the whole mass; those situated near the periphery aremerely a little more closely approximated than the internal, and are ratherthinner than thicker than the latter. The liber-like fibrous layer is verythick ; the rind thick, irregularly torn, and weathered. The ligneous bundlesare sometimes rather soft, as in Corypha cerifera, but also sometimes veryhard, as in Cocos coronata. On account of the uniform distribution of thevascular bundles, the stem is nearly as hard in the middle as in the outerpart, and on account of the great number of bundles, it presents considerablesolidity. This form of stem occurs in Cocos, Leopoldinia, Sgagrus, Elais,Corypha; Rhapis flabelliformis and Lepidocaryum gracile form the transitionto the cane-like stems.

5. Stemless Palms. In some the length is so small that the plants seemto be stemless. Two varieties occur. In the first the stem is abbreviated,like a bulb. This is not peculiar to any special genus, but occurs in indivi-dual species of the most varied genera, e. g. in Geonoma acaulis, macrostachys ;Astrocaryum acaule, campestre ; Diplothemium maritimum, campestre, littorale.