Dense but flexible wood – How leaf nodes impact xylem mechanics in Juglans californica
In: IAWA JournalABSTRACT
A node is the point of attachment of the leaf to the stem of a plant; gaps associated with nodes have been viewed as discontinuities of the stem vascular system. We tested the hypothesis that the node/gap is a spring-like joint that impacts stem flexibility even well after the leaves have been shed, with some stems specialized for elongation and others for flexibility. Four-point bending tests were done using an Instron Mechanical Testing Device with the independent variable being the number of nodes in the stem segment and dependent variables being Modulus of Elasticity (MOE), Modulus of Rupture (MOR), and xylem density. Node anatomy was examined microscopically to assess structure and function. The stiffness of the stem was inversely proportional to the frequency of leaf nodes. Surprisingly, xylem density was inversely proportional to the frequency of leaf nodes in stems of adult trees. The tissue around nodes/gaps consisted of twisted and contorted cells that may be effective at absorbing compressive and tensile stresses. Because nodes behave as spring-like joints, the frequency of nodes relates to function, with some stems specialized for vertical expansion and others for light capture and damping of wind stress. The ultimate stems on a tree are the most bendable, which may allow the trees to avoid breakage.
Purchase
Buy instant access (PDF download and unlimited online access):
Institutional Login
Log in with Open Athens, Shibboleth, or your institutional credentials
Personal login
Log in with your brill.com account
-
Caringella MA , Bergman BA , Stanfield RC , Ewers MM , Bobich EG , Ewers FW . 2014. Effects of phyllotaxy on biomechanical properties of stems of Cercis occidentalis (Fabaceae). Am. J. Bot. 101: 206–210. DOI: .
-
Duarte D. 2013. Plastic responses of wood development in California black walnut (Juglans californica): effects of irrigation and post-fire growth. Master’s Thesis, California State Polytechnic University, Pomona.
-
Gere JM , Timoshenko SP . 1984. Mechanics of materials, Ed. 2. Belmont Inc., Wadsworth, California.
-
Goodrich KR , Ortiz LA , Coughlin DJ . 2016. Unusual twig “twistiness” in pawpaw (Asimina triloba) provides biomechanical protection for distal foliage in high winds. Am. J. Bot. 103: 1872–1879. DOI: .
-
Grant DJ , Anton A , Lind P . 1984. Bending strength, stiffness, and stress-grade of structural Pinus radiata: Effect of knots and timber density. New Zeal. J. For. Sci. 14: 331–348.
-
Niklas KJ . 1992. Plant biomechanics: an engineering approach to plant form and function. University of Chicago Press.
-
Niklas KJ . 1997. Responses of hollow, septate stems to vibrations: biomechanical evidence that nodes can act mechanically as spring-like joints. Ann. Bot. 80: 437–448. DOI: org/10.1006/anbo.1997.0463.
-
Niklas KJ , Spatz H , Vincent J . 2006. Plant biomechanics: an overview and prospectus. Am. J. Bot. 93: 1369–1378. DOI: .
-
Ozden S. 2016. The relationship between the anatomy and mechanical properties of different green wood species. Doctoral Dissertation, University of Manchester.
-
Panshin AJ , De Zeeuw C . 1980. Textbook of wood technology, Ed. 4. McGraw-Hill, New York.
-
Richter JP . 1970. The notebooks of Leonardo da Vinci: Vol. 1. Dover Publications, New York.
-
Rowe N , Speck T . 2005. Plant growth forms: an ecological and evolutionary perspective. New Phytologist 166: 61–72. DOI: .
-
Ruzin SE . 1999. Plant microtechnique and microscopy. Oxford University Press.
-
Salleo S , Lo Gullo MA . 1986. Xylem cavitation in nodes and internodes of whole Chorisia insignis H. B. et K. plants subjected to water stress: relations between xylem conduit size and cavitation. Ann. Bot. 58: 431–441.
-
Slater D , Bradley RS , Withers PJ , Ennos AR . 2014. The anatomy and grain pattern in forks of hazel (Corylus avellana L.) and other tree species. Trees 28: 1437–1448.
-
Tyree MT , Zimmermann MH . 2002. Xylem structure and the ascent of sap. Ed. 2. Springer-Verlag, New York.
-
Ugural AC . 1991. Mechanics of materials. McGraw-Hill, New York.
-
Utsumi Y , Bobich EG , Ewers FW . 2010. Photosynthetic, hydraulic and biomechanical responses of Juglans californica shoots to wildfire. Oecologia 164: 331–338. DOI: .
-
Vogel S. 2003. Comparative biomechanics: life’s physical world. Princeton University Press.
-
Zimmermann MH , Sperry JS . 1983. Anatomy of the palm Rhapis excelsa. IX: Xylem structure of the leaf insertion. J. Arnold Arbor. 64: 599–609.
| All Time | Past Year | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 1063 | 275 | 32 |
| Full Text Views | 740 | 0 | 0 |
| PDF Views & Downloads | 106 | 0 | 0 |
Dense but flexible wood – How leaf nodes impact xylem mechanics in Juglans californica
In: IAWA JournalABSTRACT
A node is the point of attachment of the leaf to the stem of a plant; gaps associated with nodes have been viewed as discontinuities of the stem vascular system. We tested the hypothesis that the node/gap is a spring-like joint that impacts stem flexibility even well after the leaves have been shed, with some stems specialized for elongation and others for flexibility. Four-point bending tests were done using an Instron Mechanical Testing Device with the independent variable being the number of nodes in the stem segment and dependent variables being Modulus of Elasticity (MOE), Modulus of Rupture (MOR), and xylem density. Node anatomy was examined microscopically to assess structure and function. The stiffness of the stem was inversely proportional to the frequency of leaf nodes. Surprisingly, xylem density was inversely proportional to the frequency of leaf nodes in stems of adult trees. The tissue around nodes/gaps consisted of twisted and contorted cells that may be effective at absorbing compressive and tensile stresses. Because nodes behave as spring-like joints, the frequency of nodes relates to function, with some stems specialized for vertical expansion and others for light capture and damping of wind stress. The ultimate stems on a tree are the most bendable, which may allow the trees to avoid breakage.
| All Time | Past Year | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 1063 | 275 | 32 |
| Full Text Views | 740 | 0 | 0 |
| PDF Views & Downloads | 106 | 0 | 0 |