Journal article

Publication year: 2002

Pages: 729-739

Journal: Plant Biology

Volume number: 4

Issue number: 6

ISSN: 1435-8603

DOI Link: https://doi.org/10.1055/s-2002-37404

Publisher: Wiley

Abstract: 
Two types of negatively geotropic aerial roots may be observed on the root system of Laguncularia racemoso: pneumatophores with secondary growth, and short-lived pneumathodes which remain in the primary anatomical state. The pneumathodes distinguish themselves by the absence of an epidermis; instead, the outer cortex takes the place of the outermost tissue. This tissue forms a three-dimensional network of rod-like cells and gas spaces. The cell walls contain a lipophilic substance which ensures that the intercellular spaces remain gas-filled during submergence. An uniseriate cellular layer separates the outer and inner cortex. This uniseriate cellular layer, which we term a "pore layer", is characterized by cells with suberized and lignified cell walls and occasional pores among the cells. The pores permit the diffusion of oxygen-rich air from the surface of the pneumathode to the aerenchyma of the inner cortex and the escape of carbon dioxide from the interior of the root. The structure of the differentiated pneumathode originates from frequent cell divisions in the part of the apical meristem where the outer cortex emerges. Because of the pressure thereby exerted on the epidermis and hypodermis, these two cell layers tear and become separated from the outer cortex. Their remnants remain visible at the base of the pneumathode and as an appendage of the calyptra. The function and significance of the pneumathodes for L. racemosa are discussed. An extract of Xanthoria parietina was employed as a new fluorescent dye to stain suberine in cell walls. The staining technique is presented in this paper.

Harvard Citation style: Geissler, N., Schnetter, R. and Schnetter, M. (2002) The pneumathodes of Laguncularia racemosa:: Little known rootlets of surprising structure, and notes on a new fluorescent dye for lipophilic substances, Plant Biology, 4(6), pp. 729-739. https://doi.org/10.1055/s-2002-37404

APA Citation style: Geissler, N., Schnetter, R., & Schnetter, M. (2002). The pneumathodes of Laguncularia racemosa:: Little known rootlets of surprising structure, and notes on a new fluorescent dye for lipophilic substances. Plant Biology. 4(6), 729-739. https://doi.org/10.1055/s-2002-37404