Features of the Secondary Xylem that Facilitate Branch Abscission in Juvenile Wollemia Nobilis

IAWA Journal ◽  
2008 ◽  
Vol 29 (3) ◽  
pp. 225-236 ◽  
Author(s):  
R.D. Heady ◽  
G.E. Burrows
Keyword(s):  
Water Supply ◽  
Secondary Xylem ◽  
Sectional Area ◽  
Cross Sectional ◽  
First Order ◽  
Order Branch ◽  
Bordered Pits ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Wollemi pine (Wollemia nobilis) does not shed individual leaves but instead cleanly self-prunes the whole first-order branch with all the leaves still attached. A zone of stranded xylem at the branch base, the site of branch abscission, is described here in relation to the profusion of bordered pits and ray parenchyma cells that occur in this region. We propose that the much higher occurrence frequencies of these two features, compared to those in the stem and in the outer regions of the branch, results in a zone of radially-orientated weakness which facilitates branch abscission. We also suggest that since the stranded xylem region has a smaller cross-sectional area than the outer regions of the branch, the prevalence of bordered pits promotes water flow, and thus may alleviate the effects of this region on water supply to the foliage. Our observations represent, to the best of our knowledge, the first report of the involvement of bordered pits and ray parenchyma in branch abscission.

Distributional variation of lignin and non-cellulosic polysaccharide epitopes in different pit membranes of Scots pine and Norway spruce seedlings

IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 407-429 ◽  
Author(s):  
Jong Sik Kim ◽  
Geoffrey Daniel
Keyword(s):  
Monoclonal Antibodies ◽  
Norway Spruce ◽  
Scots Pine ◽  
Distribution Patterns ◽  
Staining Intensity ◽  
Rhamnogalacturonan I ◽  
Bordered Pits ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Microdistribution of non-cellulosic polysaccharides in pit membranes of bordered pits (intertracheid pits between adjacent tracheids), cross-field pits (half bordered pits between tracheids and ray parenchyma cells) and ray pits (simple pits in nodular end walls of ray parenchyma cells) was investigated in mature earlywood of juvenile Scots pine and Norway spruce seedlings using immunocytochemistry combined with monoclonal antibodies specific to (1→4)-β-galactan (LM5), (1→5)-α-arabinan (LM6), homogalacturonan (HG, LM19, LM20), xyloglucan (LM15), xylan (LM10, LM11) and mannan (LM21, LM22) epitopes. Using phloroglucinol-HCl and KMnO4 staining, lignin distribution in pit membranes was also examined. Apart from cross-field pit membranes in Scots pine, all pit membranes observed showed a positive reaction for lignin with differences in staining intensity. Ray pit membranes showed strongest reaction with lignin staining in both species. Intensity of lignin staining in bordered pit membranes was stronger in Norway spruce than in Scots pine. With localization of non-cellulosic polysaccharide epitopes, Scots pine showed differences in cross-field pit membranes (rhamnogalacturonan-I (RG-I), HG and xyloglucan epitopes) from bordered and ray pit membranes (RG-I and HG epitopes). In contrast, Norway spruce showed significant differences in ray pit membranes (RG-I, HG, xyloglucan, xylan and mannan epitopes) from bordered and cross-field pit membranes (HG and no/trace amount of RG-I epitopes). Distributional differences in HG epitopes depending on antibody type/ membrane regions were also observed in cross-field pit membranes between the two species. Together, the results suggest that distribution patterns of lignin and non-cellulosic polysaccharides in pit membranes differ significantly between pit types and between Scots pine and Norway spruce. Compared with the same types of pit membranes in hardwoods, the results for Scots pine and Norway spruce (softwoods) differed significantly.

FORMATION OF SUCCESSIVE CAMBIA IN THE MENISPERMUM TREE COCCULUS LAURIFOLIUS (MENISPERMACEAE)

IAWA Journal ◽  
2015 ◽  
Vol 36 (4) ◽  
pp. 400-408 ◽  
Author(s):  
Kishore S. Rajput ◽  
Sangeeta Gupta
Keyword(s):  
Cell Division ◽  
Tree Species ◽  
Secondary Xylem ◽  
Vessel Diameter ◽  
Outer Side ◽  
Successive Cambia ◽  
Meristematic Cells ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Successive cambia are often associated with the climbing or shrub habit, and is less common in trees. We studied formation of successive cambia and structure of secondary xylem in young stems of Cocculus laurifolius DC., a tree species of Menispermaceae. Cell division in the vascular cambium ceased in pencil-thick stems. Subsequently, parenchyma cells located outside the perivascular fibre cap re-differentiated and gave rise to several small segments of meristematic cells, of which the central cells divided repeatedly to initiate the first successive cambium which produces secondary xylem centripetally and phloem centrifugally. Cells located on the inner side of the newly initiated cambium differentiated into conjunctive tissue while cells on the outer side of it divided further and differentiated into sclereids. Xylem was diffuse porous and composed of vessels, fibre tracheids and ray parenchyma cells, and only differed in vessel diameter from wide-vessel climbing relatives.

Stem anatomy at various developmental stages of secondary growth in Turbina corymbosa (Convolvulaceae)

2018 ◽  
Vol 151 (2) ◽  
pp. 219-230 ◽  
Author(s):  
Manoj M. Lekhak ◽  
Amit D. Gondaliya ◽  
Shrirang R. Yadav ◽  
Kishore S. Rajput
Keyword(s):  
Secondary Xylem ◽  
Secondary Growth ◽  
Growth Patterns ◽  
Stem Anatomy ◽  
Successive Cambia ◽  
Background Population ◽  
Short Period ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Background – Population growth of lianas in the tropical forest is credited to their ability of CO2 sequestration and efficiency of the narrow stems to supply water required for the amount of foliage it bears. Turbina corymbosa (L.) Raf. (Convolvulaceae Juss.) is one of the fast-growing invasive species of scrambling woody lianas. It covers trees entirely within a short period to compete with above-ground resources (particularly sunlight). However, no information is available on how it manages to cope up with an increasing demand of water supply and mineral nutrients. What are the structural and developmental patterns adapted by this species to expand the stem diameter for efficient supply of below-ground resources? Therefore, our aim was to investigate the secondary growth patterns and structure of secondary xylem and phloem in T. corymbosa.Methods – Several samples of the stem with various diameters were studied using a histological method. Morphological and anatomical analyses were carried out using light microscopy.Key results – With the initiation of secondary growth, stems lose their circular outline rapidly due to unequal deposition of secondary xylem and formation of successive cambia. New successive cambia initiate from parenchymatous cells as small crescent-shaped fragments on asymmetric/opposite sides and result in a different stem conformation. Though several segments of successive cambia are formed, very few stem samples form complete cambium rings. The secondary xylem formed by successive cambia is diffuse porous with indistinct growth rings and is composed of both wide and narrow (fibriform) vessels, tracheids, fibres, axial and ray parenchyma cells. The secondary phloem consists of sieve tube elements, companion cells, axial and ray parenchyma cells. In fully grown plants, cambial action (internal cambium) occurrs between the intraxylary phloem and protoxylem and produces secondary xylem and phloem near the pith region.Conclusion – Structural alterations and unequal deposition of conducting elements, occurrence of intraxylary phloem and flattening of the stem are suggested to facilitate rapid growth of the plants by providing required minerals and nutrients. Internal cambium formed at the periphery of the pith is bidirectional and produces secondary xylem externally and intraxylary phloem internally. Continued development of intraxylary phloem from the internal cambium provides an additional path for rapid and safe translocation of photosynthates.

Traumatic Gum-Resin Cavities in the Stem of Ailanthus Excelsa Roxb.

IAWA Journal ◽  
1987 ◽  
Vol 8 (2) ◽  
pp. 167-174 ◽  
Author(s):  
A.M. Babu ◽  
G.M. Nair ◽  
J.J. Shah
Keyword(s):  
Epithelial Cells ◽  
Secondary Xylem ◽  
Ailanthus Excelsa ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Cells ◽  
Cell Layers ◽  
Ethephon Treatment ◽  
Xylem Elements ◽  
Ray Parenchyma Cells

Traumatic gum-resin cavities develop in the secondary xylem of the stem of Ailanthus excelsa Roxb. in response to fungal infection and ethephon treatment. After infection or ethephon treatment, traumatic parenchyma in several cell layers develops instead of normal secondary xylem elements. It consists of unlignified axial and ray parenchyma cells. Vessels and fibres are absent. Gum-resin cavities in one or two tangential rows develop in this tissue by the lysis of its axial parenchyma cells. The cavities are bordered by an epithelium. A few layers of traumatic parenchyma cells adjacent to the epithelial cens become meristematic and appear cambiform. The epithelial cells undergo lysis and they evidently contribute to gum-resin formation. As the lysis of epithelial cens proceeds, the adjacent cambiform cens divide to form additional epithelial cells. The process continues for some time and eventually an the axial cells of the traumatic parenchyma break down forming a tangentially anastomosing network of cavities. The cavities do not traverse the ray cells, and the multiseriate rays remain intact like bridges amidst the ramifying cavities.

WOOD ANATOMY OF MYRCIARIA, NEOMITRANTHES, PLINIA AND SIPHONEUGENA SPECIES (MYRTEAE, MYRTACEAE)

IAWA Journal ◽  
2013 ◽  
Vol 34 (3) ◽  
pp. 313-323 ◽  
Author(s):  
Gabriel U.C.A. Santos ◽  
Cátia H. Callado ◽  
Marcelo da Costa Souza ◽  
Cecilia G. Costa
Keyword(s):  
Wood Anatomy ◽  
Growth Rings ◽  
Anatomical Features ◽  
Bordered Pits ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Square Cells ◽  
Ray Parenchyma Cells ◽  
Perforation Plates ◽  
Fruit Characters

Myrciaria, Neomitranthes, Plinia and Siphoneugena are closely related genera whose circumscriptions are controversial. The distinctions between Myrciaria vs. Plinia, and Neomitranthes vs. Siphoneugena, have been based on a few fruit characters. The wood anatomy of 24 species of these genera was examined to determine if wood anatomical features could help delimit the genera. It was determined the four genera cannot reliably be separated by wood anatomy alone. Characteristics seen in all four genera are: growth rings usually poorly-defined; diffuse porous; exclusively solitary vessels, usually circular to oval in outline; simple perforation plates; vessel-ray pits alternate and distinctly bordered; fibers with distinctly bordered pits in radial and tangential walls, usually very thickwalled; vasicentric tracheids typically absent; scanty paratracheal parenchyma, sometimes unilateral, and diffuse to diffuse-in-aggregates; chambered crystalliferous axial parenchyma in many species, usually both prismatic and smaller crystals; rays 1–4-seriate, uniseriate rays composed of upright/square cells, multiseriate rays with procumbent body cells and 1 to many marginal rows of upright/square cells; disjunctive ray parenchyma cells usually present.

scholarly journals Development of Successive Cambia and Structure of Secondary Xylem of Ipomoea Obscura (Convolvulaceae)

2014 ◽  
Vol 59 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Kishore S. Rajput ◽  
Bharat D. Chaudhary ◽  
Vidya S. Patil
Keyword(s):  
Secondary Xylem ◽  
Vascular Bundles ◽  
Growth Rings ◽  
Sieve Elements ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Thin Walled ◽  
Ray Parenchyma Cells ◽  
Ipomoea Obscura

Abstract Stems of Ipomoea obscura Ker Gawl., increase in thickness by forming multiple rings of cambia. Stems 5-6 mm thick produce parenchymatous derivatives which divide repeatedly to form small arcs of cambium. Several such small arcs initiate simultaneously and form a ring of small cambial arcs. After the formation of a few xylem and phloem elements, all these arcs are interconnected by transdifferentiation of parenchyma cells present between the cambial arcs and constitute a complete cambial cylinder. This newly formed cambium is functionally bidirectional: earlier- formed arcs produce xylem centripetally and phloem centrifugally, while later-formed segments exclusively produce thin-walled parenchyma cells on either side. Young stems are circular in cross section but as stem thickness increases they become oval to elliptic or lobed and dumbbell-shaped. Xylem rays are mostly uni- or biseriate and thin-walled, but multiseriate rays characteristic for a climbing habit are observed occasionally. In thick stems, the marginal ray parenchyma in most of the samples becomes meristematic and develops ray cambia which exclusively produce sieve elements. Similarly, parenchyma cells produced from later-formed cambial segments give rise to several irregularly oriented vascular bundles. The secondary xylem is diffuse porous, with indistinct growth rings and is composed of fibriform and wider vessels, fibres, and axial and ray parenchyma cells, while phloem consists of sieve elements, companion cells, and axial and ray parenchyma cells.

Ray Structure Differences between Rootwood and Stemwood in a Range of Softwood Species

IAWA Journal ◽  
2009 ◽  
Vol 30 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Pat Denne ◽  
Siân Turner
Keyword(s):  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Structural Differences ◽  
Ray Parenchyma Cells ◽  
Practical Implications ◽  
Softwood Species

Differences between the ray structure of rootwood and stemwood were analysed in 11 species from 5 families of gymnosperms. Rootwood was consistently found to have fewer ray tracheids, with ray parenchyma cells which were taller axially, wider tangentially, but shorter radially, and had more pits per cross-field than stemwood. A scale for quantifying types of cross-field pitting is proposed, and statistically significant differences in type and diameter of cross-field pitting were found between rootwood and stemwood of most species sampled. These structural differences have practical implications for identification of gymnosperm roots, and for distinguishing between rootwood and stemwood.

Ray Structure in Root- and Stem-Wood of Larix Decidua: Implications for Root Identification and Function

IAWA Journal ◽  
2008 ◽  
Vol 29 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Pat Denne ◽  
Peter Gasson
Keyword(s):  
Wood Anatomy ◽  
Larix Decidua ◽  
Stem Wood ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells ◽  
And Function

Differences in ray structure between root- and stem-wood of softwoods can cause confusion in identifying roots using keys based on stem-wood anatomy. Comparison of root- and stem-wood rays of Larix decidua showed root-wood had fewer ray tracheids, taller, wider but shorter ray parenchyma cells, and larger cross-field pits than stem-wood. The implications of these differences are considered in relation to the identification and function of roots.

INHIBITION OF WATER CONDUCTIVITY CAUSED BY WATERMARK DISEASE IN SALIX SACHALINENSIS

IAWA Journal ◽  
2000 ◽  
Vol 21 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Yasuaki Sakamoto ◽  
Yuzou Sano
Keyword(s):  
Wood Anatomy ◽  
High Moisture ◽  
Water Conductivity ◽  
X Ray ◽  
Salix Sachalinensis ◽  
Water Conduction ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
High Moisture Level ◽  
Ray Parenchyma Cells

Water conduction and wood anatomy of Salix sachalinensis attacked by watermark disease were investigated. The internal symptom, the watermark, appeared as a brown to brown-black stained zone in sapwood. Dye injection tests revealed that water conduction did not take place in the watermark. However, soft X-ray photography and cryo-scanning electron microscopy revealed that the watermark had a high moisture level. In the watermark, some of the vessels were plugged with tyloses and masses of bacteria, and some of the ray parenchyma cells caused necrosis. Hence, the non-conductive watermark in sapwood can be considered similar to discoloured wood or wetwood.

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