The apparent trunk of an immature banana plant is a false-stem made up of close-fitting leaf sheaths, through the center of which the fruit-bearing shoot forces its way. Contrary to the usual impression, this aerial stem is leafy almost to the top of the inclosing false-stem, and bears the largest leaves produced by the plant. The phyllotaxy changes with the age and size of the plant from about f in very young plants, through 3/7 in half grown specimens, to 4/9 in mature individuals. The change to a greater divergence is hastened by good illumination. The lateral buds are not axillary, but arise opposite the axil in the angle between the margins of the sheath. As the tightly convolute lamina pushes up through the center of the false-stem, it is preceded by the precursory appendage, which forces a passage and prevents the premature unfurling of the lamina through friction against the surrounding sheath. Thus, although no physiological function of the appendage is known, its mechanical function is evident. In unfurling, the precursory appendage and a dome which terminates the relaxed coils of the blade are torn away by a tear which extends entirely across the end of the right half of the lamina. After it has expanded, the wind frays the lamina, which is destitute of mechanical elements which might resist a tear parallel to its veins, into narrow strips. The borders of these false pinnae, the scars left by the loss of the scarious margin which surrounds the young leaf, and the wound left by the detachment of the dome and the appendage, are all closed by the suberization of pre-existing tissues. The protoxylem elements which differentiate in the basal intercalary growing zone of the leaf sheath are soon pulled apart, and the lacunae left by their disruption are completely filled by the ingrowth of neighboring parenchyma cells. A similar destruction and obliteration of protoxylem elements occurs in the midrib and the principal veins of the lamina, but not in the subordinate veins. The veins, although almost parallel, diverge slightly as they depart from the midrib. New veins, which arise blindly in the tissue, are intercalated between the primary veins, so that despite the divergence of the latter, vascular bundles are as close together at the margin as near the midrib. All of the veins are interconnected by commissural vascular bundles which are very efficient in the conduction of water to a portion of the lamina of which the veins have been severed. Stomata are scattered over all of the inclosed portions of the sheaths and stem, even on parts which never come into contact with air. On the lamina their frequency is very variable. Their density is greater near the midrib than near the margin, and in the apical and middle portions than in the basal; this rule holds for both surfaces. In sheaths which are separated from the exterior of the false-stem by 4 or more others, the hypodermal layer on the outer (abaxial) side is composed of cells with thin cellulose walls. As these sheaths are forced toward the exterior, these walls become gradually thicker, and give first the reactions of suberin, then finally those of lignin. The change in the character of the walls is correlated with the penetration of sunlight. The 2 cell-layers next beneath the epidermis of the lower side of the midrib are also thickened and lignified. In conclusion, attention is called to the large number of wounds, caused by the destruction of internal as well as external tissues, which the leaf suffers during its normal development, its unfurling, and its readjustment to the environment.