The functional significance of palisade tissue: penetration of directional versus diffuse light

Authors

  • T. C. VOGELMANN,

    Corresponding author
    1. Department of Botany, University of Wyoming, Laramie WY 82071, USA
      Thomas C. Vogelmann, Botany Department, P.O. Box 3165 University Station, University of Wyoming, Laramie WY 82071, USA.
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  • G. MARTIN

    1. Department of Botany, University of Wyoming, Laramie WY 82071, USA
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    • *

      Department of Cell Biology and Anatomy, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.


Thomas C. Vogelmann, Botany Department, P.O. Box 3165 University Station, University of Wyoming, Laramie WY 82071, USA.

ABSTRACT

Light gradients were measured in leaves that had different types of anatomical development of the mesophyll but similar pigment content. Leaves of the legume, Thermopsis montana, had columnar palisade and spongy mesophyll whereas leaves of the monocot, Smilacina stellata, had spongy mesophyll only. Light gradients were measured at 550 nm in both types of leaves when they were irradiated with collimated or diffuse light. When irradiated with collimated light, light gradients were steeper in leaves with spongy mesophyll in comparison to those that had palisade tissue. On the other hand, light gradients were similar between both leaf types when they were irradiated with diffuse light. Thus, columnar palisade cells facilitated the penetration of collimated light over diffuse light. These results suggest that palisade tissue may help distribute light more uniformly to chloroplasts within the leaf. Moreover, the functional significance of palisade tissue may be related to the amount of collimated light within the natural environment.

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