FROST RING FORMATION IN THE STEMS OF SOME CONIFEROUS SPECIES

1966 ◽  
Vol 44 (7) ◽  
pp. 879-886 ◽  
Author(s):  
C. Glerum ◽  
J. L. Farrar
Keyword(s):  
Normal Form ◽  
Dead Cell ◽  
Subsequent Growth ◽  
Conifer Species ◽  
Coniferous Species ◽  
Cell Tissue ◽  
Parenchyma Cells ◽  
Ray Cells ◽  
Xylem Ray Cells ◽  
Mother Cells

Seedlings of several conifer species were artificially subjected to freezing temperatures. Microscopic examination of sections, taken at intervals after the frost, revealed the way in which frost rings developed. Differentiating tracheids and xylem mother cells were killed by the frost, leaving a permanent band of underlignified and crumpled tracheids inside a band of dead cell tissue. Most of the cambial initials remained alive but developed abnormally into short irregular tracheids. Parenchyma cells proliferated mainly from the xylem ray cells. With subsequent growth, the growing stresses, which had become subnormal because of the collapse of killed cells, were restored. This was accompanied by the reestablishment of the cambium to its normal form.

scholarly journals Size variation in the vascular cambium and its derivatives in two Alstonia species

2007 ◽  
Vol 21 (3) ◽  
pp. 531-538 ◽  
Author(s):  
Moin A. Khan ◽  
Badruzzaman Siddiqui
Keyword(s):  
Size Variation ◽  
Tropical Tree Species ◽  
Edaphic Conditions ◽  
Appreciable Increase ◽  
Ray Cells ◽  
Fusiform Initials ◽  
Xylem Ray Cells ◽  
Mother Cells ◽  
Xylem Fibers ◽  
Fusiform Initial

Two tropical tree species viz. Alstonia venenata Br. and Alstonia neriifolia Don. (Apocynaceae) were investigated to detect size variation in different elements of the cambium and its derivative tissues. Although these two species were grown under identical climatic and edaphic conditions, fusiform initial dimensions and the elements derived from them were larger in A. venenata than in A. neriifolia. Ray initials are rectangular in A. venenata but isodiametric in A. neriifolia. An appreciable increase in length was observed in the phloem and xylem ray cells when compared to the mother cells. Maximum elongation was observed in xylem fibers during differentiation from the respective fusiform initials.

Ultrastructural Changes in the Cell Walls of Cambial Derivatives During Wood Formation in Indian ELM (Holoptelea Integrifolia)

IAWA Journal ◽  
2012 ◽  
Vol 33 (4) ◽  
pp. 403-416 ◽  
Author(s):  
Karumanchi S. Rao ◽  
Yoon Soo Kim ◽  
Pramod Sivan
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Middle Lamella ◽  
Ultrastructural Changes ◽  
Cell Wall Polysaccharides ◽  
Lignin Distribution ◽  
Parenchyma Cells ◽  
Ray Cells ◽  
Xylem Elements ◽  
S2 Layer

Sequential changes occurring in cell walls during expansion, secondary wall (SW) deposition and lignification have been studied in the differentiating xylem elements of Holoptelea integrifolia using transmission electron microscopy. The PATAg staining revealed that loosening of the cell wall starts at the cell corner middle lamella (CCML) and spreads to radial and tangential walls in the zone of cell expansion (EZ). Lignification started at the CCML region between vessels and associated parenchyma during the final stages of S2 layer formation. The S2 layer in the vessel appeared as two sublayers,an inner one and outer one.The contact ray cells showed SW deposition soon after axial paratracheal parenchyma had completed it, whereas noncontact ray cells underwent SW deposition and lignification following apotracheal parenchyma cells. The paratracheal and apotracheal parenchyma cells differed noticeably in terms of proportion of SW layers and lignin distribution pattern. Fibres were found to be the last xylem elements to complete SW deposition and lignification with differential polymerization of cell wall polysaccharides. It appears that the SW deposition started much earlier in the middle region of the fibres while their tips were still undergoing elongation. In homogeneous lignin distribution was noticed in the CCML region of fibres.

scholarly journals Conservation Hedges:

2019 ◽  
pp. 71-100
Author(s):  
Martin Gardner ◽  
Tom Christian ◽  
William Hinchliffe ◽  
Rob Cubey
Keyword(s):  
Genetic Material ◽  
Taxus Baccata ◽  
Wild Populations ◽  
Botanic Garden ◽  
Small Space ◽  
Conifer Species ◽  
Safe Sites ◽  
Coniferous Species ◽  
Great Capacity ◽  
Large Numbers

In May 2014, the first planting of the Royal Botanic Garden Edinburgh (RBGE) conservation hedge took place, when the Reverend Anne Brennan planted a tree which had originated as a cutting from the ancient and historic European yew, Taxus baccata, in the churchyard of her church at Fortingall, Perthshire. This is one of almost 2,000 plants that will eventually form a conservation hedge of significant scientific and conservation value. The International Conifer Conservation Programme (ICCP), based at RBGE, has actively sought other opportunities to establish conservation hedges via its network of ‘safe sites’, using a range of different conifer species. This initiative is being driven by the potential for relatively large numbers of genotypes from a single threatened species to be stored in a linear space. It is well established that seed banks have a great capacity to store large amounts of genetic diversity, so we should simply consider conservation hedges in a similar manner. These super-hedges cram relatively large amounts of genetic material into a small space, capturing a great range of wild traits and potentially contributing to the restoration of wild populations. To date, conservation hedges have been planted at five separate locations at RBGE’s Edinburgh Garden as well as at four ICCP external ‘safe sites’. Although this article focuses on the establishment of conservation hedges using conifers, we have also highlighted some conservation hedges that comprise non-coniferous species.

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.

Vertical and Radial Variation of Nuclear Elongation Index of Living Sapwood Ray Parenchyma Cells in a Plantation Tree of Cryptomeria Japonica

IAWA Journal ◽  
1994 ◽  
Vol 15 (3) ◽  
pp. 323-327 ◽  
Author(s):  
K.C. Yang ◽  
Y.S. Chen ◽  
C.A. Benson
Keyword(s):  
Metabolic Activity ◽  
Cryptomeria Japonica ◽  
Ground Level ◽  
Tree Crown ◽  
Growth Rings ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Cells ◽  
Elongation Index ◽  
Ray Parenchyma Cells

Vertical and radial variations of nuclear elongation index (NEI) of living sapwood ray parenchyrna cells were studied in a 45-year-old plantation tree of Cryptomeria japonica D. Don collected in Taiwan on February 27, 1992. Nine wood strips oriented in an E-W direction of the tree were collected starting at 0.3 m above ground level, and progressing upwards by 2.5 m intervals to the tree crown. Radial sections, 20 µm thick, were cut from the cambium toward the inner sapwood of these nine wood strips. The nuclear elongation index (NEI) was used to express the metabolic activity of the ray cells. It was found that metabolic activity of sapwood ray parenchyma was thc highest at the outer sapwood and declined gradually towards the inner sapwood. The lowest average NEI was found at the lowest stern level. The average NEI of various stern height levels increased with increasing stern height level. The average NEI of three growth rings at the outer sapwood near the cambium reached a maximum at the bottom of the live crown.

A CONTRIBUTION TO THE CONCEPT OF WOUND REPAIR IN WOODY STEMS

1954 ◽  
Vol 32 (3) ◽  
pp. 486-490 ◽  
Author(s):  
W. George Barker
Keyword(s):  
Wound Repair ◽  
Callus Tissue ◽  
The Body ◽  
Ray Cells ◽  
Cambial Zone ◽  
Healing Of Wounds ◽  
Xylem Ray Cells ◽  
Secondary Wood

Those xylem ray cells closely associated with the cambial zone will unite in proliferating with other cells recently derived from the cambium following the wounding of a basswood stem. However, ray cells remote from the cambium, although potentially meristematic, will fail to divide. Nonetheless these latter will grow out occasionally when the ray, exposed during the culturing operation, is closely connected with actively growing callus tissue. Parenchyma throughout the body of the secondary wood of the basswood has been shown to proliferate whenever a mass is exposed which is considerably larger in volume than a normal multiseriate ray. The healing of wounds in the linden best should be considered as a function of active, newly formed, cambial derivatives and not as a reaction dominated by any one tissue.

Structure and ontogeny of the fissured stems of Callaeum (Malpighiaceae)

IAWA Journal ◽  
2017 ◽  
Vol 38 (1) ◽  
pp. 49-66 ◽  
Author(s):  
Pablo A. Cabanillas ◽  
Marcelo R. Pace ◽  
Veronica Angyalossy
Keyword(s):  
Secondary Xylem ◽  
Vascular System ◽  
Secondary Growth ◽  
Natural Fracture ◽  
Production Rates ◽  
Axial Parenchyma ◽  
Parenchyma Cells ◽  
Ray Cells ◽  
Cambial Variant ◽  
Stem Development

Stem ontogeny and structure of two neotropical twining vines of the genus Callaeum are described. Secondary growth in Callaeum begins with a typical regular cambium that gradually becomes lobed as a result of variation in xylem and phloem production rates in certain portions of the stem aligned with stem orthostichies. As development progresses, lignified ray cells of the initially formed secondary xylem detach on one side from the adjacent tissues, forming a natural fracture that induces the proliferation of both ray and axial nonlignified parenchyma. At the same time, parenchyma proliferation takes place around the pith margin and generates a ring of radially arranged parenchyma cells. The parenchyma generated in this process (here termed disruptive parenchyma) keeps dividing throughout stem development. As growth continues, the parenchyma finally cleaves the lignified axial parts of the vascular system into several isolated fragments of different sizes. Each fragment consists of xylem, phloem and vascular cambium and is immersed in a ground matrix of disruptive parenchyma. The cambium present in each fragment divides anticlinally to almost encircle each entire fragment and maintains its regular activity by producing xylem to the centre of the fragment and phloem to the periphery. Additionally, new cambia arise within the disruptive parenchyma and produce xylem and phloem in various polarities, such as xylem to the inside and phloem to the outside of the stem, or perpendicularly to the original cambium. Unlike the very distinctive stem anatomical architecture resulting from this cambial variant in Callaeum, its secondary xylem and phloem exhibit features typical of lianas. These features include very wide conducting cells, abundant axial parenchyma, high and heterocellular rays and gelatinous fibres.

scholarly journals Proteins present in tannin cenocyte mother cells in Sambucus racemosa L.

2015 ◽  
Vol 46 (1) ◽  
pp. 47-55 ◽  
Author(s):  
A. M. Zobel
Keyword(s):  
Protein Content ◽  
Free Acid ◽  
Nucleus Size ◽  
Basic Proteins ◽  
Parenchyma Cells ◽  
Tannin Cells ◽  
Mother Cells ◽  
Parenchymal Cells

It has been demonstrated that protein content and concentration are higher in mononucleate tannin-cells than in the parenchyma cells of <i>Sambucus racemosa</i>. Cytoplasmic and nuclear free acid proteins markedly prevail here. It is believed that they may be enzymatic proteins. Increase of acid proteins content within the nucleus of tannin cells causes an increase of the nucleus size. The content of nuclear bound basic proteins in tannin cells, may be lower than in the neighbouring parenchymal cells.

Changes in carbohydrates and ultrastructure in xylem ray cells ofPopulus in response to chilling

PROTOPLASMA ◽  
1987 ◽  
Vol 137 (1) ◽  
pp. 45-55 ◽  
Author(s):  
J. J. Sauter ◽  
Sabine Kloth
Keyword(s):  
Ray Cells ◽  
Xylem Ray Cells

scholarly journals Ground beetles (Coleoptera: Carabidae) as predators of conifer seeds

2019 ◽  
Vol 46 (1) ◽  
pp. 37-44
Author(s):  
Zdenka Martinková ◽  
Stanislava Koprdová ◽  
Ján Kulfan ◽  
Peter Zach ◽  
Alois Honěk
Keyword(s):  
Pinus Sylvestris ◽  
Choice Experiments ◽  
Ground Beetles ◽  
Mortality Factor ◽  
Conifer Species ◽  
Coniferous Species ◽  
Conifer Seeds ◽  
Pterostichus Melanarius ◽  
Polygonum Lapathifolium ◽  
Seed Coats

AbstractMany species of ground beetles (Coleoptera: Carabidae) are important predators of seeds. While the consumption of herb seeds has been intensively studied, little attention has been paid to the consumption of seeds of gymnosperm plants. Here, we determined the consumption of seeds of six coniferous species by four common carabid species and compared carabid preference for conifer and selected common angiosperm weed seed species. In no-choice experiments, the large carabid species Pseudoophonus rufipes preferentially consumed the seeds of Picea abies, Larix decidua and Pinus sylvestris. Pinus sylvestris was also preferred by another large carabid, Pterostichus melanarius. The smaller carabids Harpalus affinis and H. rubripes consumed conifer seeds reluctantly. The intensity of seed consumption by carabids decreased with increasing seed size. In choice experiments, both of the large carabid species preferred the small conifer seeds of P. sylvestris and L. decidua over herb seeds of similar size (Dipsacus fullonum, Galeopsis speciosa, Polygonum lapathifolium). Carabids may prefer conifer seeds because of their soft seed coats, regardless of their chemical protections. Postdispersal predation of seeds by carabids may be an important mortality factor in some conifer species.

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