• B G L Swamy

      Articles written in Proceedings – Plant Sciences

    • The aim and scope of plant morphology—II

      K Periasamy B G L Swamy

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      Evolution was in the beginning applied to the species. When genetics established the independent inheritance of characters, evolution also began to be analysed in terms of characters or organs, each considered independent in its evolutionary trend. Subsequently, however, this rule of independence began to be violated in the attempts to determine evolutionary status by correlation. Furthermore, the circumscription of an organ for evolutionary correlation is equivocal. With regard to the vegetative and floral morphology of the angiosperms, the concepts of old formal morphology in terms of fundamental organs were more definite and evolution has not been able to offer anything better. Many of the concepts of formal morphology havein toto been transferred to evolution.

      The principles laid down by Carlquist, in what he has proposed to be a function oriented approach to angiosperm morphology, appear to be based on undue assumptions with a mixing up of homology and evolution. The decline of evolution as the directive force behind plant morphology necessitates new approaches that could impart dynamism to this basic discipline of botanical study.

    • On the origin of vascular cambium in dicotyledonous stems

      B G L Swamy K V Krishnamurthy

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      The present paper reviews the relationship between the procambium and the vascular cambium. It is suggested that the procambium is not a pre-requisite for the formation of vascular cambium, even in the stems, as is claimed by several morphologists.

    • Embryogenesis in sexual and asexual species ofZeuxine (Orchidaceae)

      K Ananda Karanth B G L Swamy Govindappa D Arekal

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      The development of the zygote following sexual union inZeuxine longilabris exhibits a predetermined polarity and patternized sequence of developmental stages leading to the initiation of cotyledonary and epicotylary activity in adjacent sectors, both being terminal on the embryonal axis. The cotyledonary growth is incipient and the epicotylary sector is distinguishable only by histological distinctivity. The initiation and trend of growth of the asexual embryo totally deviates from that of its sexual counterpart. Although incipient and inconsistent polarity becomes established in the dividing nodular cell system eventually the embryos end up as a spindle-shaped structure of homogeneous cells where not even the initiation of root and shoot polar differentiation is seen either within or without. Under these circumstances the asexual embryos are broadly comparable to the earlier stages in the development of embryoids in free cell cultures.

    • On embryos and embryoids

      B G L Swamy K V Krishnamurthy

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      The ontogeny of the embryoids arising from a variety of somatic and male gametophytic tissues has been compared to that of a zygote embryo; it has often been stressed that a free cellrecapitulates the ontogenetic sequence of stages that are seen in the development of a zygote into an embryo. An embryoid significantly lacks a polarised ontogenetic pattern throughout the gamut of differentiation; it lacks typical centres of polar organization like the hypophysis and the epiphysis in early ontogeny; the protoderm formation is belated and also incomplete; the organization of tap root is suppressed. In spite of assuming exomorphic contours comparable with those of the gross developmental stages recognized in embryogenesis consequential to sexual fusion, the embryoid is devoid of internal differentiation both in degree and pattern. Under these circumstances the ontogeny of an embryoid never stands comparison with that of a zygotic embryo. From the morphological standpoint an embryoid is more closely related to a shoot bud.

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