• Amiya Datta

      Articles written in Proceedings – Section B

    • Root initiation in the adult axes of a few dicotyledonous species

      Amiya Datta Girija P Majumdar

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      Six additional cases of naturally occurring shoot-borne adventive roots on adult axes of herbaceous dicotyledons have been described in this paper.

      These support the view of Priestley and Swingle that the site of initiation of a lateral root in adult hypocotyls and intemodes moves inwards from the pericycle to the flanks of the vascular cambium close to the newly differentiated xylem and phloem.

      The radial growth of the hypocotyl ofCucurbita maxima is maintained by the independent growth of the vascular bundles, the interfascicular cambium helping the primary rays in keeping pace with the growth in thickness of the former.

    • Comparative study of the vegetative and flowering axes ofLeonurus sibiricus L.

      Amiya Datta

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      In the study of the anatomy of the vegetative and flowering regions ofLeonurus, three important features have been observed:

      The unbranched condition of the flowering axis with extreme reduction of leaf lamina;

      The greater activity of cambium in vegetative than in the flowering region which appears to be due to the difference of photosynthetic activities in the two regions of the plant; and

      The endodermis which is well developed in the flowering region is only a ‘starch sheath’ in the vegetative region. The change from starch sheath to endodermis appears to be concerned with the xeromorphy of the flowering region indicated by the extreme reduction of the leaf lamina in this region.

    • Developmental studies - I. origin and development of axillary buds with special reference to two dicotyledons

      G P Majumdar Amiya Datta

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      Detailed studies on the initiation and development of axillary buds inHeracleum andLeonurus have been reported in this paper.

      Works so far done on this problem in Ferns, Monocotyledons and Dicotyledons have been briefly reviewed.

      In Ferns an axillary bud is initiated in thedetached (apical)meristem on the free surface of the axis or “in proximity to meristele conjunctions“. In Monocotyledons initiation takes place in the surface layer of thecorpus, on the side opposite to the insertion of, and in association with, the leaf primordium just above the one in Whose axil the bud appears. Hence Hsü (1944) describes the origin as ‘endogenous’ in Monocotyledons. In Dicotyledons though Goebel reports origin from the embryonal meristem a little behind the apex, Koch, Majumdar and Datta report origin in the vacuolating cells of the adaxial epidermis of the subtending leaf opposite the median bundle inSyringa, Heracleum andLeonurus.

      In the shoot apices of Ferns, Monocotyledons and Dicotyledons leaf primordia are laid down first and buds are initiated in their axils later. A year may elapse between the laying down of the axillant leaves and formation of buds in their axils as reported in the winter buds ofSyringa.

      Bud trace originates in the bud primordium and then differentiates backwards into theleaf- cushion outside the axial ring of vascular bundles, finally it enters the ring to unite with one of its synthetic bundles.

      As the buds normally originate in the axils of leaves which are removed some distance from the apex and which are growing vigorously or unfolding, it is suggested that their initiation is due to some physiological processes than to any specific qualities inherent in the apical meristem.

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