S. K. Purkayastha , S. P. Agrawal , R. D. Tandon , Laxmi Chauhan

Abstract

The variation in the proportion of heartwood has been studied in 89 years old Eucalyptus tereticornis Sm. trees, raised in four different plantations viz. Haldwani, Shahdol, Bangalore and Coimbatore. The heartwood volume calculated from its propogation in various discs, has been found to be significantly affected by the locality of growth; within a locality it is correlated with the girth at breast height.

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S. K. Purkayastha , K. N. Bahadur

Abstract

Corneveceue a heterogeneous family. Except tor the genus Cornus, all other Indian genera previously dealt with under this family have been transferred to small segregate families: Alangium has been shifted to Alangiaceae, Mastixia to Mastixiuceae, Acuba to Aucubaceae, Nyssa to Nyssaceae, Toricellia to Toricelliaceae and Helwingin to Helwinjiaceae. Leaving out the Mastixiaceae, this segregation, on naorphological and wood anatomical grounds, appears to be justified. The persent study indicates that the last named should he regarded as a subfamily Mastixioideae under the Cornaceae. The characteristics and the main pointa or difference between the Cornaceae and the segregate families are discussed. The genua Cornus has been delimited in different ways by various workers, some accepting the genus in a broad sense and dividing it into sub-genera and sections, other sagregating these groups as distinct genera. The characters used for sub-dividing Cornus do not seem to be sufficient for recognising the segregate genera. The genus has, therefore, been divided into 8 sub-genera whose characters are furnished. The distinguishing features of the Indian species together with their relevant synonyms and distribution are also given.

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Man Mohan Singh , S. K. Purkayastha , P. P. Bhola , A. K. Gupta

Abstract

A fresh study of the suitablity of Melia azedarach for pulp and paper has shown that it is a very promising raw material for wrapping, writing aDd printing paper provided the trees are grown not too fast. Very fast grown material is characterised by very low specific gravity and wide fibres with large lumen. These fibres collapse due to their thin walls during the course of sheet formation resulting in poor strength properties. The earlier reports on its unsuitability were apparently based on tests carried out on very fast grown material.

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Man Mohan Singh , S. K. Purkayastha , P. P. Bhola , Krishna Lal , Swarna Singh

Abstract

Fibre morphology and pulp strength of twelve species of bamboos grown in the arboratum of the Forest Research Institute, Dehra Dun were studied in two sets of pulps. In all the species fibre dimensions and particularly lumen width were found to vary widely indicating highly heterogenous nature of the pulp. The fibre dimensions were also significantly different in the two sets. Parenchyma proportions were also found to be different in the two sets. No marked differences were found in the various species as regards chemical composition of either chips or pulps, as well as alkali consumed during pulping. But, wide differences were found in strength properties, in unbeaten and beaten pulps of the 12 species of bamboos studied. However, these differences were considerably reduced on beating. As the ranking of tbe species on the basis of strength in unbeaten and beaten conditions is different strength of beaten pulp cannot be predicted from the unbeaten one. Further, significant differences were observed between the two sets of pulps in both unbeaten and beaten hand sheets. No relationships could be found between the fibre characteristics and the pulp strength properties, It appears from this study that because of wide variations within a species, fibre characteristics cannot be used as a criterion for classifying the bamboos for paper and pulp production. On the basis of pulp yield, alka1i consumption and sheet properties of the 12 species, they have been graded and Dendrocalamus hamiltonii has been found to be the best.

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S. K. Purkayastha , B. Lal

Abstract

The plant remains excavated from the Neolithic site Burzahom (circa 1535 B.C. to circa 2375 B.C.) is Kashmir showed that the "burnt material of ceiling" consisted mostly charred twigs of Parrotiopsis and Prunus. The bark Hakes found in them probably belong to Prunus sp. The plant remains also include a number of samples of deteriorated wood samples of Myricaria sp. which probably date back to 4th century A.D. There is no evidence to support the view that the area abounded in birch (Betula sp.) as the name of the place would indicate.

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S. S. Ghosh , K. Ramesh Rao , S. K. Purkayastha

Abstract

Variations in structure and quality of some Indian hardwoods are discussed with special reference to rate of growth. Though considerable work has been done in India and other countries on non-porous and ring-porous woods, hardly any information is available on diffuse-porous woods. As Indian timbers mostly belong to this group an attempt has been made in this paper to bring out some salient trends, observed at the Forest Research Institute, Dehra Dun, which may be of interest to workers in other tropical countries.

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S. S. Ghosh , S. K. Purkayastha

Abstract

The gum of Acacia senegal comes from gum cysts which develop in the inner bark of some trees. These cysts are developed in tangential rows in the axial parenchyma strands of the phloem adjacent to the cambial zone. They are first initiated schizogenously but later on enlarge considerably due to the breakdown of the surrounding cells (lysigenously). These cysts do not have any definite shape or size and in longitudinal sections, they appear as vertically aligned, sinuous and sometimes interconnected passages ending abruptly. The specimens showing spontaneous exudation of gum indicated that the development of these cysts is preceded by certain widespread changes like profuse development of parenchymatous tissues, disappearance of starch, etc., both in the xylem and phloem, as well as disintegration of the pith. The formation of gum ducts and other changes, however, occur only in localized areas of the stem. Blazing the tree also sometimes results in the formation of similar gum cysts in the bark but, unlike the case of natural exudation, the structure of the xylem does not change to any great extent. Rod-shaped bacteria have been found to be conspicuous in all the tissues affected by gummosis. These bacteria have also been noticed in other tissues of the phloem and xylem and the exact significance of their presence is not clear. The probable reasons for the development of gum cysts have been discussed in the light of the anatomical changes observed.

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S. S. Ghosh , S. K. Purkayastha

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Resin canals in Boswellia serrata are long tubular structures which ramify both vertically and horizontally in the tree. Although, they are present in all parts of the stem, viz., bark, wood and pith, they are most abundant in the bark where both vertical and horizontal types occur. In the wood, only horizontal canals are present while in the pith only vertical canals are found. In the bark the vertical canals branch freely and some times also anastomose in the parenchymatous regions of the phloem. These are also connected with the horizontal ones which are again continuous from the bark to the wood. These horizontal canals confined to the rays, are unbranched and mostly appear to end blindly in the weed. A few of these, hcwever, run along the entire radii of the wood being connected with the vertical canals of the pith. The latter, however, are short unbranched structures only. All these canals originate schizogenously, but branching of the canals is accompanied by certain amount of cell disintegration. Blazing the tree for the gum-oleoresin does not affect the structure of the bark or wood to any great extent except that the number of horizontal canals increases appreciably in the new tissues formed after tapping both in the bark and the wood.

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S. S. Ghosh , S. K. Purkayastha

Abstract

Anogeissus latifolia Wall. trees which yield "Ghatti Gum" of commerce do not normally possess gum canals either in the bark or in the wood. The gum that is exuded usually comes out from the gum pockets formed as a result of some injury in the bark. When the trees are heavily injured, gum canals are developed in the cambial zone and take part also in the exudation of gum. These canals though vertically aligned are not long as the effects of the wound are rather localized. The gum pockets and the gum canals are formed lysigenously by the dissolution of tissues. The injury also brings about certain other anatomical changes particularly in the region of the secondary phloem. The most notable changes are in the increase in the size and number of sclerosed cells which become very conspicuous in the bark. The traumatic gum canals in the wood are also characteristic due to their shape, size and arrangement.

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K. Ramesh Rao , S. K. Purkayastha , R. D. Tandon

Abstract

Study of several consecutive growth rings in two samples of teak from Mysore and Kerala showed no definite relationship between ring width and proportion of tissues. The two samples also showed significant differences in proportion of tbaues though the average rate of growth is comparable.

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Man Mohan Singh , S. K. Purkayastha , P. P. Bhola , Laxmi Sharma

Abstract

By testing hand sheets made from 32 mixtures of different fractions of a pulp of Dendrocalamus striclus, beaten to 250 ml. (C.S.F.), the effect of variations in fibre dimensions on strength properties have been investigated. Fibre length, determined from unbeaten pulp, accounts for 77 to 90 per cent of the variation in strength properties viz. breaking length, burst factor and tear factor. Other fibre characteristics viz. ratio of lumen width to fibre diameter and percentage of fibres with obliterated lumen, which also exhibit similar relationship with the strength properties, are highly correlated with fibre length. Parenchyma proportion shows a high negative correlation with the sheet properties. Fibre length and parenchyma proportion together account for 94 per cent of the variation in strength properties.

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S. K. Purkayastha , R. D. Tandon , K. Ramesh Rao

Abstract

Anatomical studies of some tested samples of teak from seven different localities have shown that fibre wall thickness is highly correlated with specific gravity. This relationship is influenced to some extent by the proportion of fibres. Highly significant correlation has also been found to exist between fibre wall thickness and maximum crushing stress in the samples in which the wall thickness is less than 4μ.

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S. K. Purkayastha , R. D. Tandon , K. Ramesh Rao

Abstract

Study of some increment cores from 36-year-old teak trees from four seed origins grown in South Coimbatore, indicates that seed source may have a significant effect on the density of the mature wood. Increment cores from trees of two of the seed origins were also studied from another locality viz. Nilambur. Analysis of the data from these two localities suggests that the influence of environment on wood density may be greater than that of seed origin.

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S. K. Purkayastha , Krishna Lal , K. Ramesh Rao , G. S. Negi

Abstract

Variation in anatomical structure and density has been studied in the main hole of a 25 year old tree of Michelia champaca grown at Newforest, Dehra Dun. For studying the variation from pith to periphery, consecutive blocks comprising 2-3 rings were taken along one radius and at two heights. For variations from bottom to top, two growth sheaths were investigated at eight levels. All anatomical data except fibre length were collected from cross sections by the point sampling method. There is no evidence of any consistent pattern in the variation in anatomical structure within the tree. However the fibre length shows a tendeney to increase from the pith outwards and to decrease from the bottom upwards though the trend in both cases is somewhat irregular. Density values within the tree also show a similar irregular trend. Both anatomical structure and density on the whole vary within rather narrow limits within a growth sheath except near the ground level. Study of the correlation between anatomical structure and density has shown that wall thickness, diameter and length of fibres account for 77 per cent of the variation in density. The proportion of fibres appears to have no significant effect on density.

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S. K. Purkayastha , K. R. Satyamurthi

Abstract

Analysis of the data on wood specific gravity and rate of growth of teak from two seed origins grown at South Coimbatore and Nilambur showed that locality has a highly significant effect while the variation due to seed origin was not significant.

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