An Anatomical Assessment of Branch Abscission and Branch-base Hydraulic Architecture in the Endangered Wollemia nobilis

G. E. Burrows; P. F. Meagher; R. D. Heady
April 2007
Annals of Botany;Apr2007, Vol. 99 Issue 4, p609
Academic Journal
Background and Aims The branch-base xylem structure of the endangered Wollemia nobilis was anatomically investigated. Wollemia nobilis is probably the only extant tree species that produces only first-order branches and where all branches are cleanly abscised. An investigation was carried out to see if these unusual features might influence branch-base xylem structure and water supply to the foliage. Methods The xylem was sectioned at various distances along the branch bases of 6-year-old saplings. Huber values and relative theoretical hydraulic conductivities were calculated for various regions of the branch base. Key Results The most proximal branch base featured a pronounced xylem constriction. The constriction had only 14–31 % (average 21 %) of the cross-sectional area and 20–42 % (average 28 %) of the theoretical hydraulic conductivity of the more distal branch xylem. Wollemia nobilis had extremely low Huber values for a conifer. Conclusions The branch-base xylem constriction would appear to facilitate branch abscission, while the associated Huber values show that W. nobilis supplies a relatively large leaf area through a relatively small diameter ‘pipe’. It is tempting to suggest that the pronounced decline of W. nobilis in the Tertiary is related to its unusual branch-base structure but physiological studies of whole plant conductance are still needed.


Related Articles

  • Daytime Depression in Tree Stem CO2 Efflux Rates: Is it Caused by Low Stem Turgor Pressure? An Saveyn; Kathy Steppe; Raoul Lemeur // Annals of Botany;Mar2007, Vol. 99 Issue 3, p477 

    Background and Aims Daytime CO2 efflux rates (FCO2) from tree stems are often reported to be lower than expected from the exponential relationship between temperature and respiration. Explanations of daytime depression in FCO2 have focused on the possible role of internal CO2 transport in the...

  • Xylem hydraulics: Rising up and higher! Amritphale, Dilip; Sharma, Santosh K. // Resonance: Journal of Science Education;Mar2010, Vol. 15 Issue 3, p223 

    This article attempts to examine how xylem hydraulic function is related to the size and redundancy of conduits and whether xylem hydraulic constraint limits tree height.

  • Caspase inhibitors affect the kinetics and dimensions of tracheary elements in xylogenic Zinnia (Zinnia elegans) cell cultures. Twumasi, Peter; Iakimova, Elena T.; Qian, Tian; van Ieperen, Wim; Schel, Jan H. N.; Emons, Anne Mie C.; van Kooten, Olaf; Woltering, Ernst J. // BMC Plant Biology;2010, Vol. 10, p162 

    Background: The xylem vascular system is composed of fused dead, hollow cells called tracheary elements (TEs) that originate through trans-differentiation of root and shoot cambium cells. TEs undergo autolysis as they differentiate and mature. The final stage of the formation of TEs in plants is...

  • Xylem production in six tree species growing on an island in the boreal forest region of western Quebec, Canada. Ko Heinrichs, Derrick; Tardif, Jacques C.; Bergeron, Yves // Canadian Journal of Botany;May2007, Vol. 85 Issue 5, p518 

    Xylem production was studied by repeatedly taking microcore samples from the stems of six tree species growing on the “réserve écologique des Vieux-Arbres”, on Lake Duparquet, Québec, throughout the 1999 growing season. Species examined were paper birch (Betula papyrifera...

  • Maturation of the tracheary elements in the roots of Pinus banksiana and Eucalyptus grandis. Taylor, J H; Peterson, C A // Canadian Journal of Botany;Jul2001, Vol. 79 Issue 7, p844 

    Tracheary elements of the xylem are responsible for the longitudinal (axial) transport of water and ions that have moved radially across the root. These vessel members and (or) tracheids mature some distance behind the root tip, and it is generally believed that this distance is directly related...

  • How to quantify conduits in wood? Scholz, Alexander; Klepsch, Matthias; Karimi, Zohreh; Jansen, Steven // Frontiers in Plant Science;Feb2013, Vol. 4, p1 

    Vessels and tracheids represent the most important xylem cells with respect to long distance water transport in plants. Wood anatomical studies frequently provide several quantitative details of these cells, such as vessel diameter, vessel density, vessel element length, and tracheid length,...

  • Tensile and compressive stresses in tracheids are induced by swelling based on geometrical constraints of the wood cell. Burgert, Ingo; Eder, Michaela; Gierlinger, Notburga; Fratzl, Peter // Planta;Jul2007, Vol. 226 Issue 4, p981 

    Plants are able to pre-stress their tissues in order to actuate their organs. Here, we demonstrate with two tissue types of the secondary xylem of conifers (normal wood and compression wood of spruce ( Picea abies)) that either tensile or compressive stresses can develop in the longitudinal...

  • Unusual Metaxylem Tracheids in Petioles of Amorphophallus (Araceae) Giant Leaves. HEJNOWICZ, ZYGMUNT // Annals of Botany;Sep2005, Vol. 96 Issue 3, p407 

    • 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...

  • INSIDE A ROSE CANE PART II: PITH AND XYLEM. Ritchie, Gary A. // American Rose;Jan/Feb2010, Vol. 40 Issue 7, p28 

    The article examines the cross section of a rose cane, focusing on the tissue called the pith and the layers of xylem that surround it. The pith is right at the center of the cane and is the plant's storage for water and nutrients. It is a soft tissue that is susceptible to attack from boring...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics