Anatomy of the Axis of the Banana

  • Authors : Skutch, A.F.

  • Document type : Journal article

  • Year of publication : 1932

  • Journal title : Botanical Gazette

  • Volume (number) : 93 (3)

  • Pages : 233-258

  • Peer-reviewed : No

  • ISSN : 0006-8071

  • Language(s) : English

  • Abstract : Although the development and anatomy of the inflorescence, the root, and the leaf of the banana have recently been the subject of studies, no detailed investigation appears ever to have been made of the anatomy of the axis. Numerous incidental references to the rhizome of the banana may be found in the literature, however, to the more important of which allusion will be made in due course. In the present paper the term "axis" is employed in its widest sense, to include the rhizome or bulb, the aerial stem, and the rhachis of the inflorescence.

    [Summary] 1. Close behind the apex of the bulb of the banana there develops a cambium-like meristem of limited duration, whose chief function is the origination of the adventive roots and the vascular bundles which link them with the leaf-trace bundles. 2. The number of tangential divisions which each cambium cell undergoes is rarely greater than seven, but the meristem is constantly regenerated from the adjacent undifferentiated cells of the inner cortex. 3. A single daughter cell of the cambium gives rise to an entire segment of a vascular bundle, as in the arborescent Liliiflorae. 4. The cambium gives rise first to longitudinal amphiphloic bundles, then to horizontal amphiphloic bundles and to the primordia of the adventive roots, which arise always in longitudinal rows of four. After initiating the horizontal bundles the meristem loses its activity, at about 3.5 cm. from the apex. The region of its activity extends for about 3 cm. in all. 5. The parenchymatous cells which stand in the way of the adventive roots pushing out through the cortex are softened by an enzyme secreted from the tip of the root, but a "digestive pocket" appears never to be present. 6. The strongest leaf-trace bundles penetrate to the center of the bulb. Thence they may pass outward toward the cortex in any direction, either by continuing across to the side opposite their point of entry, by doubling back to the side from which they entered, or by bending to right or left. As they approach the secondary zone on their outward course they incline downward and finally enter it. Their course through the central cylinder is everywhere extremely tortuous. 7. The longitudinal secondary bundles, formed from the cambium, are merely the downward prolongations of the leaf-trace bundles. The same bundle which in the upper portion of its course is collateral becomes amphiphloic at its lower extremity. 8. The horizontal secondary bundles radiate from the bases of the roots and form a system girdling the bulb. Through their anastomoses with the longitudinal bundles they conduct water to the leaves. 9. The courses of the vascular bundles of the aerial stem do not differ essentially from those of the bulb, save that they are straight and regular. 10. The tracheids of both aerial stem and leaf sheath attain a maximum length of 8 cm. Those between 4 and 6 cm. long are numerous. 11. The latex vessels are formed of chains of large cells joined by a wide perforation occupying almost the entire end wall. The central region of the end wall is torn away from the narrow peripheral region, but usually remains attached at one side, forming a loose flap.


  • Open access : No

  • Document on publisher's site : close View article on publisher's site

  • Musalit document ID : IN180530

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