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K. A. Chowdhury , S. S. Ghosh

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K. A. Chowdhury , S. S. Ghosh

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

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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 , K. Ramesh Rao

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This paper deals with some abnormal aspects of growth and its effect on cell structure and properties of hardwoods. While considerable work has been done elsewhere, little information was available on this aspect of tree growth in India. Observations are recorded as made recently at the Forest Research Institute, Dehra Dun, India, on the occurrence of tension wood in Indian timbers and its influence on some of their properties.

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S. S. Ghosh , B. S. Negi

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Anatomical structure of epidermis of monocotyledons has often been of great practical value in identification. In the case of bamboos, epidermal studies have got special significance as floral characters are not readily available due to the flowering taking place only once in their life time. With a view to assess the diagnostic value of stem epidermis of Indian bamboos, six important species viz., Bambusa arundinacea Willd., B. Polymorpha Munro, B. vulgaris Schrad, Dendrocalamus membranaceus Munro, D. strictus Nees and Melocanna bambusoides Trin. have been investigated. The size, frequency, distribution and other characteristics of various epidermal structures useful in identification have been recorded and depicted. The exodermic epidermal appendages such as hairs and spines which commonly occur on the bamboo skin have also been studied and recorded.

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S. S. Ghosh , R. Shahi

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An altogether new scented wood of India sold under the name "Taggar wood" has been found to be Hemicyclia porteri Gamble. Its anatomical and other characteristics have been described in detail. Distinguishing features of this and other well-known scented woods of the world have also been discussed together with the description of the genuine taggar wood (Cinnamosma fragrans Baill.) of Madagascar to facilitate their easy determination.

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S. S. Ghosh

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Based on the study of plant-remains excavated from different parts of India, the antiquity of rice (Oryza spp.) has been traced up to pre-vedic times. The oldest direct evidence of rice has been discovered from Lothal in Gujarat which is considered to be a southward extension of the Harappa culture. The archeological age of this material has been assigned to Circa 2,300 B.C. The data available so far on various other rice remains from ancient India have been recorded in this paper chronologically and according to geographical distribution.

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S. S. Ghosh , S. K. Purkayastha

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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

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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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