Skip Navigation



AOBPreview published online on June 29, 2005
Annals of Botany, doi:10.1093/aob/mci198
This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
96/3/407    most recent
mci198v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by HEJNOWICZ, Z.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by HEJNOWICZ, Z.
Agricola
Right arrow Articles by HEJNOWICZ, Z.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2005. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oupjournals.org
Received February 12, 2005
Revised March 31, 2005
Accepted May 12, 2005

Article

Unusual Metaxylem Tracheids in Petioles of Amorphophallus (Araceae) Giant Leaves

ZYGMUNT HEJNOWICZ 1*

1 Department of Biophysics and Cell Biology, Silesian University, Jagiellonska 28, Katowice 40-032, Poland

* To whom correspondence should be addressed.
ZYGMUNT HEJNOWICZ, E-mail: jkarcz{at}us.edu.pl


  Abstract

• Background and Aims Petioles of huge solitary leaves of mature plants of Amorphophallus resemble tree trunks supporting an umbrella-like crown. Since they may be 4 m tall, adaptations to water transport in the petioles are as important as adaptations to mechanical support of lamina. The petiole is a cylindrical shell composed of compact unlignified tissue with a honeycomb aerenchymatous core. In both parts numerous vascular bundles occur, which are unique because of the scarcity of lignified elements. In the xylemic part of each bundle there is a characteristic canal with unlignified walls. The xylem pecularities are described and interpreted.

• Material Vascular bundles in mature petioles of Amorphophallus titanum and A. gigas plants were studied using light and scanning electron microscopy.

• Key Results The xylemic canal represents a file of huge metaxylem tracheids (diameter 55-200 µm, length >30 mm) with unlignified lateral walls surrounded by turgid parenchyma cells. Only their end walls, orientated steeply, have lignified secondary thickenings. The file is accompanied by a strand of narrow tracheids with lignified bar-type secondary walls, which come into direct contact with the wide tracheid in many places along its length.

• Conclusions The metaxylem tracheids in A. petioles are probably the longest and widest tracheids known. Only their end walls have lignified secondary thickenings. Tracheids are long due to enormous intercalary elongation and wide due to a transverse growth mechanism similar to that underlying formation of aerenchyma cavities. The lack of lignin in lateral walls shifts the function of ‘pipe walls’ to the turgid parenchyma paving the tracheid. The analogy to carinal canals of Equisetum, as well as other protoxylem lacunas is discussed. The stiff partitions between the long and wide tracheids are interpreted as structures similar to the end walls in vessels.

Keywords: Apoplasm, Amorphophallus titanum, A. gigas, cohesion-tension theory, lignification, metaxylem, petiole, protoxylem lacuna, tracheid length.
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.