Wood cells accumulate the major proportion of terrestrial biomass in their thick cell walls, composed of cellulose, matrix polysaccharides and lignin. By interacting with cellulose and lignin, matrix polysac- charides affect mechanical and chemical properties of cell walls in developing and mature wood cells, which determines wood quality traits, such as fiber length, wood and fiber strength and durability, and properties important in industrial wood processing such as pulping and saccharification. Our research is aiming at elucidating these matrix functions and effects in wood cells.

Mellerowicz Ewa 1150Matrix polysaccharides are synthesized and modified by Carbo- hydrate Active Enzymes (CAZYmes) and by enzymes acting on non-carbohydrate types of side chains.These enzymes reside either in the Golgi apparatus where they synthesise matrix polymers, or in cell walls where they modify them post-synthet- ically.We analyzed the genomic complement of CAZYmes in Populus and identified the ones highly expressed in developing wood. Similar analyses are currently being carried out in Picea. Co-expression analyses help us to identify novel unknown function genes that may be involved in matrix biosynthesis or modification. Most studied genes belong to large multi-gene families whose members may have distinct or overlapping functions, or else be non-functional copies.Their functions are studied using transgenic Populus and Arabidopsis.
Another tool used to study the role of different matrix com- ponents in wood properties is the transgenic overexpression of various microbial enzymes having defined specificity to matrix components in Populus. These enzymes, when targeted to cell walls,modify specific chains of the matrix,revealing their intricate interactions among different wall components and their overall role during wood cell development.

mellerowicz_1 mellerowicz_2
Matrix modification affects wood cell expansion and thus regulates the size and shape of wood cells. Fibers and vessel elements have different ways of expansion. Fibers elongate by intrusive tip growth and radially expand by symplastic growth. In contrast, vessel elements do not elongate, but they radially expand by a combination of radial intrusive and symplastic growth. Accordingly, a highly regulated modification of matrix in developing wood cells is required to achieve these different effects. A model of growth stress generation and XET action in maturing fibers. Crystallization of cellulose microfibrils (single beige rods) around xyloglucan (yellow) would generate longitudinal tensional stress within the macrofibril (large beige rods) during fiber maturation. XET enzyme (blue) is present associated with xyloglucan between wall layers. Any displacement between the wall layers driven by the shrinkage of cellulose macrofibrils will be quickly stopped by the XET-mediated transglycosylation to a free xyloglucan acceptor thus creating a cross-link between cell wall layers.

mellerowicz 3Activity of XET enzyme in the specific cell wall layers visualized by the incorporation of the fluorescent substrate to the XET transglycosylation product. Such activity could be detected in tension wood fibers years after their initiation, indicating that the matrix is being modified even in dead cells.We have found that pectin matrix, which cements wood cells together, is extensively modified during xylogenesis. Pectin methyl esterases (PME) remove methyl ester side chains, which makes the pectin matrix susceptible to degradation by pectate lyases or polygalacturonases, and prone to formation of intra-molecular cross-links involving calcium ions that rigidify the walls.We have found that pectin desterification by PME1 inhibits the intrusive tip growth of fibres and radial expansion of vessel elements. Surprisingly, pectin integrity was found to affects wood extractability and saccharification even though pectin is a minor component of wood.This suggests that pectin and xylan could be interconnected in wood cell walls.l

Hemicelluloses bind to cellulose fibrils by hydrogen bonding and potentially can cross-link them, which is thought to deter- mine wall mechanical properties. Indeed, the modification of xyloglucan by xyloglucan endotransglycosylases (XETs) affected wood cell growth.We found that they mediate incorporation of newly synthesized xyloglucan to the tightly-bound xyloglucan cell wall network, and that they also act on cell walls after cell death. Such long-lived enzymatic activity could mediate devel- opment of growth stresses in the wood. We have recently discov- ered that substantial xylan transglycosylase activity accompanies secondary wall deposition. This activity unexpectedly was found to affect the direction of cellulose microfibrils deposition in secondary walls, the mechanism of which is now being studied..
sweden_greySvensk samanfattning




Key Publications

  • Biswal AK, Soeno K, Latha Gandla M, Immerzeel P, Pattathil S, Lucenius J, Serimaa R, Hahn MG, Moritz T, Jönsson LJ, Israels- son-Nordström M, and Mellerowicz EJ. (2014) Aspen pectate lyase PtxtPL1-27 mobilizes matrix polysaccharides from woody tissues and improves saccharification yield. Biotechnology for Biofuels 7:11
  • Nishikubo N, Takahashi J, Roos AA, Derba-Maceluch M, Piens K, Brumer H, Teeri TT, Stålbrand H, Mellerowicz EJ (2011).XET-mediated xyloglucan rearrangements in developing wood of hybrid aspen (Populus tremula x tremuloides). Plant Physiol. 155: 399- 413
  • Siedlecka A, Wiklund S, Péronne MA, Micheli F, Lesniewska J, Sethson I, Edlund U, Richard L, Sundberg B, and Mellerowicz EJ. Pectin methyl esterase inhibits intrusive and symplastic cell growth in developing wood of Populus trees. (2008). Plant Physiol 146: 554- 565.
  • Gray-Mitsumune M, Blomquist K, McQueen-Mason S, Teeri TT, Sundberg B and Mellerowicz EJ (2008). Ectopic expression of a wood-abundant expansin PttEXPA1 promotes cell expansion in primary and secondary tissues in aspen. Plant Biotechnol J 6: 62-72.
  • Geisler-Lee J, Geisler M, Coutinho PM, Segerman B, Nishikubo N, Takahashi J, Aspeborg H, Djerbi S, Master E, Andersson- Gunnerås S, Sundberg B, Karpinski S, Teeri TT, Kleczkowski LA, Henrissat B, and Mellerowicz EJ. (2006). Poplar Carbohydrate- Active Enzymes (CAZymes). Gene identification and expression analyses. Plant Physiol. 140: 946-962.
  • Bourquin V, Nishikubo N, Abe H, Brumer H, Denman S, Eklund M, Christiernin M, Teeri TT, Sundberg B and Mellerowicz EJ. (2002). Xyloglucan endotransglycosylases have a function during the formation of secondary cell walls of vascular tissues. Plant Cell 14: 3073- 3088.

Cv Dr. Ewa Mellerowocz

  • 1979: MSc in Forestry, SGGW, Poland
  • 1986: MSc in Biology, University of New Brunswick, Canada
  • 1992: PhD, University of New Brunswick, Canada 1994: Post doc, Swedish University of Agricultural Sciences
  • 1995-97: Research scientist, Forest Research Institute, New Zealand
  • 1998: Research scientist, Swedish University of Agricultural Sciences
  • 1999: Assistant Professor, Swedish University of Agricultural Sciences
  • 2004: Docent, Swedish University of Agricultural Sciences
  • 2009: Professor, Swedish University of Agricultural Sciences

Publications list

  1. AspWood: High-spatial-resolution transcriptome profiles reveal uncharacterized modularity of wood formation in Populus tremula
    Plant Cell. 2017, 29 (7):1585-1604
  2. Protein expression in tension wood formation monitored at high tissue resolution in Populus
    J Exp Bot. 2017, 68 (13):3405-3417
  3. In muro deacetylation of xylan affects lignin properties and improves saccharification of aspen wood
    Biotechnol Biofuels. 2017 Apr 20;10:98 eCollection 2017
  4. Downregulation of RWA genes in hybrid aspen affects xylan acetylation and wood saccharification
    New Phytol. 2017, 214 (4):1491-1505
  5. Defense responses in aspen with altered pectin methylesterase activity reveal the hormonal inducers of tyloses
    Plant Physiol. 2017, 173(2):1409-1419
  6. Genetic analysis of fiber dimensions and their correlation with stem diameter and solid-wood properties in Norway spruce
    Genetics & Genomes (2016) 12: 123
  7. Method for accurate fiber length determination from increment cores for large-scale population analyses in Norway spruce
    HOLZFORSCHUNG, 70 (9):829-838; 10.1515/hf-2015-0138 SEP 2016
  8. Pectinous cell wall thickenings formation - A common defense strategy of plants to cope with Pb
    Environ Pollut. 2016, 214:354-361
  9. An efficient method for medium throughput screening of cuticular wax composition in different plant species
    METABOLOMICS 2016, 12 (4)
  10. Aspen tension wood fibers contain β-(1→4)-galactans and acidic arabinogalactans retained by cellulose microfibrils in gelatinous walls
    Plant Physiol. 2015, 169 (3):2048-2063
  11. Colocalization of low-methylesterified pectins and Pb deposits in the apoplast of aspen roots exposed to lead
    Environ Pollut. 2015, 205:315-326
  12. Active fungal GH115 α-glucuronidase produced in Arabidopsis thaliana affects only the UX1-reactive glucuronate decorations on native glucuronoxylans
    BMC Biotechnol. 2015, 15:56
  13. Glucuronic acid in Arabidopsis thaliana xylans carries a novel pentose substituent
    Int J Biol Macromol. 2015, 79:807-812
  14. Expression of fungal acetyl xylan esterase in Arabidopsis thaliana improves saccharification of stem lignocellulose
    Plant Biotechnol J. 2015, 14 (1):387-397
  15. Populus GT43 family members group into distinct sets required for primary and secondary wall xylan biosynthesis and include useful promoters for wood modification
    Plant Biotechnol J. 2015, 13(1):26-37
  16. Suppression of xylan endotransglycosylase PtxtXyn10A affects cellulose microfibril angle in secondary wall in aspen wood
    New Phytol. 2014, 205(2):666-681
  17. Expression of a fungal glucuronoyl esterase in Populus: Effects on wood properties and saccharification efficiency
    Phytochemistry. 2015, 112:210-220
  18. O-Acetylation of glucuronoxylan in Arabidopsis thaliana wild type and its change in xylan biosynthesis mutants
    Glycobiology. 2014; 24(6):494-506
  19. Aspen pectate lyase PtxtPL1-27 mobilizes matrix polysaccharides from woody tissues and improves saccharification yield
    Biotechnol Biofuels. 2014; 7(1):11
  20. Reduced wall acetylation proteins play vital and distinct roles in cell wall o-acetylation in Arabidopsis
    Plant Physiol. 2013; 163(3):1107-1117
  21. Aspen SUCROSE TRANSPORTER 3 allocates carbon into wood fibers
    Plant Physiology 2013; 163(4):1729-1740
  22. Xyloglucan endotransglucosylase/hydrolase (XTH) overexpression affects growth and cell wall mechanics in etiolated Arabidopsis hypocotyls
    J Experimental Botany 2013; 64 8):2481-2497
  23. Acetylation of woody lignocellulose: significance and regulation
    Front Plant Sci. 2013; 4:118
  24. Tsai AY, Canam T, Gorzsás A, Mellerowicz EJ, Campbell MM, Master ER
    Constitutive expression of a fungal glucuronoyl esterase in Arabidopsis reveals altered cell wall composition and structure
    Plant Biotechnol J. 2012 Aug 27 [Epub ahead of print]
  25. Svedström K , Lucenius J, Van den Bulcke J, Van Loo D, 4, Immerzeel P, Suuronen J-P, Brabant L, Van Acker J, Saranpää P, Fagerstedt K, Mellerowicz E, Serimaa R
    Hierarchical structure of juvenile hybrid aspen xylem revealed using X-ray scattering and microtomography
    Trees July 2012 online
  26. Gorshkova T, Brutch N, Chabbert B, Deyholos M, Hayashi T, Lev-Yadun S, Mellerowicz EJ, Morvan C, Neutelings G, Pilate G
    Plant Fiber Formation: State of the Art, Recent and Expected Progress, and Open Questions
    Crit Rev Plant Sci 2012, 31(3):201-228
  27. Wang J, Andersson-Gunnerås S, Gaboreanu I, Hertzberg M, Tucker MR, Zheng B, Leśniewska J, Mellerowicz EJ, Laux T, Sandberg G, Jones B
    Reduced expression of the SHORT-ROOT gene increases the rates of growth and development in hybrid poplar and Arabidopsis
    PLoS One. 2011;6(12):e28878. Epub 2011 Dec
  28. Mellerowicz EJ, Gorshkova TA
    Tensional stress generation in gelatinous fibres: a review and possible mechanism based on cell-wall structure and composition
    J Exp Bot: 2012, 63: 551-565
  29. Raiola A, Lionetti V, Elmaghraby I, Immerzeel P, Mellerowicz EJ, Salvi G, Cervone F, Bellincampi D
    Pectin methylesterase is induced in Arabidopsis upon infection and is necessary for a successful colonization by necrotrophic pathogens
    Molecular Plant-Microbe Interactions: 2011 24:432-440
  30. Nishikubo N, Takahashi J, Roos AA, Derba-Maceluch M, Piens K, Brumer H, Teeri TT, Stalbrand H, Mellerowicz EJ
    Xyloglucan rearrangements in developing wood of hybrid aspen
    Plant Physiology: 2011 155:399-413
  31. Nishikubo N, Takahashi J, Roos AA, Derba-Maceluch M, Piens K, Brumer H, Teeri TT, Stålbrand H, Mellerowicz EJ
    XET-mediated xyloglucan rearrangements in developing wood of hybrid aspen (Populus tremula x tremuloides)
    Plant Physiology: 2011 155:399-413
  32. Ibatullin FM, Banasiak A, Baumann MJ, Greffe L, Takahashi J, Mellerowicz EJ, Brumer H
    A real-time fluorogenic assay for the visualization of glycoside hydrolase activity in plants
    Plant Physiology: 2009 151:1741-1750
  33. Krzeslowska M, Lenartowska M, Mellerowicz EJ, Samardakiewicz S, Wozny A
    Pectinous cell wall thickenings formation-A response of moss protonemata cells to lead
    Environmental and Experimental Botany: 2009 65:119-131
  34. Kumar M, Thammannagowda S, Bulone V, Chiang V, Han K-H, Joshi CP, Mansfield SD, Mellerowicz E, Sundberg B, Teeri T, Ellis BE
    An update on the nomenclature for the cellulose synthase genes in Populus
    Trends in Plant Science: 2009 14:248-254
  35. Meng M, Geisler M, Johansson H, Harholt J, Scheller HV, Mellerowicz E, Kleczkowski LA
    UDP-glucose pyrophosphorylase is not rate limiting, but is essential in Arabidopsis
    Plant Cell Physiology: 2009 50: 998-1011
  36. Takahashi J, Rudsander UJ, Hedenström M, Banasiak A, Harholt J, Amelot N, Immerzeel P, Ryden P, Endo S, Ibatullin FM, Brumer H, del Campillo E, Master ER, Vibe Scheller H, Sundberg B, Teeri TT, Mellerowicz EJ
    KORRIGAN1 and its aspen homologue PttCel9A1 decrease cellulose crystallinity in Arabidopsis stems
    Plant and Cell Physiology: 2009 50:1099-1115
  37. Rajangam AS, Kumar M, Aspeborg H, Guerriero G, Arvestad L, Pansri P, Brown CJ, Hober S, Blomqvist K, Divne C, Ezcura I, Mellerowicz E, Sundberg B, Bolone V, Teeri TT
    MAP20, a microtubule-associated protein in the secondary cell walls of Populus tremula L. x tremuloides Michx is a target of the cellulose synthesis inhibitor, 2,6- dichlorobenzonitrile
    Plant Physiology: 2008 148:1283-1294
  38. GouéN, Lesage-Descauses MC, Mellerowicz EJ, Magel E, Label P, Sundberg B
    Microgenomic analysis reveals cell type-specific gene expression patterns between ray and fusiform initials within the cambial meristem of Populus
    New Phytologist: 2008 180:45-56
  39. Mellerowicz EJ, Sundberg B
    Wood cell walls: biosynthesis, developmental dynamics and their implications for wood properties
    Current Opinion in Plant Biology: 2008 11:293-300
  40. Nilsson J, Karlberg A, Antti H, Lopez-Vernaza M, Mellerowicz E, Perrot-Rechenmann C, Sandberg G, Bhalerao RP
    Dissecting the molecular basis of the regulation of wood formation by auxin in hybrid aspen
    The Plant Cell: 2008 20:843-855
  41. Siedlecka A, Wiklund S, Péronne M-A, Micheli F, Lesniewska J, Sethson I, Edlund U, Richard L, Sundberg B, Mellerowicz EJ
    Pectin methyl esterase inhibits intrusive and symplastic cell growth in developing wood cells of Populus
    Plant Physiology: 2008 146:554-565
  42. Wiklund S, Johansson E, Sjöström L, Mellerowicz EJ, Edlund U, Shockcor JP, Gottfries J, Moritz T, Trygg J
    Visualization of GC/TOF-MS-based metabolomics data for identification of biochemically interesting compounds using OPLS class models
    Analytical Chemistry: 2008 80: 115-122
  43. Mühlenbock P, Plaszczyca M, Plaszczyca M, Mellerowicz E, Karpinski S
    Lysigenous aerenchyma formation in Arabidopsis is controlled by LESION SIMULATING DISEASE1
    The Plant Cell: 2007 19:3819-3830
  44. Gray-Mitsumune M, Blomquist K, McQueen-Mason S, Teeri TT, Sundberg B, Mellerowicz EJ
    Ectopic expression of a wood-abundant expansin PttEXPA1 promotes cell expansion in primary and secondary tissues in aspen
    Plant Biotechnology Journal: 2008 6:62-72
  45. Nishikubo N, Awano T, Banasiak A, Bourquin V, Ibatullin F, Funada R, Brumer H, Teeri TT, Hayashi T, Sundberg B, Mellerowicz EJ
    Xyloglucan Endo-transglycosylase (XET) functions in gelatinous layers of tension wood fibers in Poplar - A glimpse into the mechanism of the balancing act of trees
    Plant Cell Physiology: 2007 48:843-855
  46. Pelloux J, Rustérucci C, Mellerowicz EJ
    New insights into pectin methylesterase structure and function
    Trands in Plant Science: 2007 12(6):267-277
  47. Meng M, Geisler M, Johansson H, Mellerowicz EJ, Karpinski S, Kleczkowski LA
    Differential tissue/organ-dependent expression of two sucrose- and cold-responsive genes for UDP-glucose pyrophosphorylase in Populus
    Gene: 2007 389:186-195
  48. Andersson-Gunneras S, Mellerowicz EJ, Love J, Segerman B, Ohmiya Y, Coutinho PM, Nilsson P, Henrissat B, Moritz T, Sundberg B
    Biosynthesis of cellulose-enriched tension wood in Populus: global analysis of transcripts and metabolites identifies biochemical and developmental regulators in secondary wall biosynthesis
    The Plant Journal: 2006 45:144-165
  49. Geisler-Lee J, Geisler M, Coutinho PM, Segerman B, Nishikubo N, Takahashi J, Aspeborg H, Djerbi S, Master E, Andersson-Gunneras S, Sundberg B, Karpinski S, Teeri TT, Kleczkowski LA, Henrissat B, Mellerowicz EJ
    Poplar carbohydrate-active enzymes. Gene identification and expression analyses
    Plant Physiology: 2006 140:946-962
  50. Aspeborg H, Schrader J, Coutinho PM, Stam M, Kallas A, Djerbi S, Nilsson P, Denman S, Amini B, Sterky F, Master E, Sandberg G, Mellerowicz E, Sundberg B, Henrissat B, Teeri TT
    Carbohydrate-active enzymes involved in the secondary cell wall biogenesis in hybrid aspen
    Plant Physiol: 2005 137:983-997
  51. Schrader J, Nilsson J, Mellerowicz E, Berglund A, Nilsson P, Hertzberg M, Sandberg G
    A high-resolution transcript profile across the wood-forming meristem of poplar identifies potential regulators of cambial stem cell identity
    Plant Cell: 2004 16:2278-2292
  52. Israelsson M, Mellerowicz E, Chono M, Gullberg J, Moritz T
    Cloning and overproduction of gibberellin 3-oxidase in hybrid aspen trees. Effects on gibberellin homeostasis and development
    Plant Physiol: 2004 135:221-230
  53. Ruiz AE, Saxena S, Schmidt J, Mellerowicz E, Miskolczi P, Bakó L, Bhalerao RP
    Differential stage-specific regulation of cyclin-dependent kinases during cambial dormancy in hybrid aspen
    Plant J: 2004 38:603-615
  54. Mitsumune MG, Mellerowicz EJ, Abe H, Schrader J, WinzEll A, Sterky F, Blomqvist K, Mason SM, Teeri TT, Sundberg B
    Expansins abundant in secondary xylem belong to subgroup A of the alpha-expansin gene family
    Plant Physiol: 2004 135:1552-1564
  55. Djerbi S, Aspeborg H, Nilsson P, Sundberg B, Mellerowicz E, Blomqvist K, Teeri TT
    Identification and expression analysis of genes encoding putative cellulose synthases (CesA) in the hybrid aspen, Populus tremula (L.) x P-tremuloides (Michx.)
    Cellulose: 2004 11:301-312
  56. Mitsumune MG, Abe H, Takahashi J, Sundberg B, Mellerowicz EJ
    Liquid phase fluorescence in situ RT-PCR analysis for gene expression analysis in woody stems
    Plant Biol (Stuttg): 2004 6:47-54
  57. Siedlecka A, Ciereszko I, Mellerowicz E, Martz Fo, Chen J, Kleczkowski LA
    The small subunit ADP-glucose pyrophosphorylase ( ApS) promoter mediates okadaic acid-sensitive uidA expression in starch-synthesizing tissues and cells in Arabidopsis
    Planta: 2003 217:184-192
  58. Shchukarev A, Sundberg B, Mellerowicz E, Persson P
    XPS study of living tree
    Surface and Interface Analysis: 2002 34:284-288
  59. Bourquin V, Nishikubo N, Abe H, Brumer H, Denman S, Eklund M, Christiernin M, Teeri TT, Sundberg B, Mellerowicz EJ
    Xyloglucan endotransglycosylases have a function during the formation of secondary cell walls of vascular tissues
    Plant Cell: 2002 14:3073-3088
  60. Mellerowicz EJ, Baucher M, Sundberg B, Boerjan W
    Unravelling cell wall formation in the woody dicot stem
    Plant Mol Biol: 2001 47:239-274
  61. Uggla C, Mellerowicz EJ, Sundberg B
    Indole- 3-acetic acid controls cambial growth in Scots pine by positional signaling
    Plant Physiology: 1998 117:113-121
  62. Mellerowicz EJ, Horgan K, Walden A, Coker A, Walter C
    PRFLL - a Pinus radiata homologue of FLORICAULA and LEAFY is expressed in buds containing vegetative shoot and undifferentiated male cone primordia
    Planta: 1998 206:619-629
  63. Lloyd AD, Mellerowicz EJ, Riding RT, Little CHA
    Changes in nuclear genome size and relative ribosomal RNA gene content in cambial region cells of Abies balsamea shoots during the development of dormancy
    Canadian Journal of Botany-Revue Canadienne De Botanique: 1996 74:290-298
  64. Mellerowicz EJ, Riding RT, Greenwood MS
    Nuclear and cytoplasmic changes associated with maturation in the vascular cambium of Larix laricina
    Tree Physiol: 1995 15:443-449
  65. Zhong Y, Mellerowicz EJ, Lloyd AD, Leinhos V, Riding RT, Little CHA
    Seasonal-Variation in the Nuclear Genome Size of Ray Cells in the Vascular Cambium of Fraxinus-Americana
    Physiologia Plantarum: 1995 93:305-311
  66. Lloyd AD, Mellerowicz EJ, Chow CH, Riding RT, Little CHA
    Fluctuations in Ribosomal-Rna Gene Content and Nucleolar Activity in the Cambial Region of Abies-Balsamea (Pinaceae) Shoots During Reactivation
    American Journal of Botany: 1994 81:1384-1389
  67. Mellerowicz EJ, Riding RT, Little CHA
    Nucleolar Activity in the Fusiform Cambial Cells of Abies-Balsamea (Pinaceae) - Effect of Season and Age
    American Journal of Botany: 1993 80:1168-1174
  68. Mellerowicz EJ, Riding RT
    Does DNA Endoreduplication Occur During Differentiation of Secondary Xylem and Phloem in Abies-Balsamea
    International Journal of Plant Sciences: 1992 153:26-30
  69. Mellerowicz EJ, Coleman WK, Riding RT, Little CHA
    Periodicity of Cambial Activity in Abies-Balsamea .1. Effects of Temperature and Photoperiod on Cambial Dormancy and Frost Hardiness
    Physiologia Plantarum: 1992 85:515-525
  70. Mellerowicz EJ, Riding RT, Little CHA
    Periodicity of Cambial Activity in Abies-Balsamea .2. Effects of Temperature and Photoperiod on the Size of the Nuclear Genome in Fusiform Cambial Cells
    Physiologia Plantarum: 1992 85:526-530
  71. Mellerowicz EJ, Riding RT, Little CHA
    Nuclear Size and Shape Changes in Fusiform Cambial Cells of Abies-Balsamea During the Annual Cycle of Activity and Dormancy
    Canadian Journal of Botany-Revue Canadienne De Botanique: 1990 68:1857-1863