• Govindappa D Arekal

      Articles written in Proceedings – Plant Sciences

    • Pollen-carriers of periplocaceae and their systematic value

      Govindappa D Arekal T M Ramakrishna

      More Details Abstract Fulltext PDF

      Pollen-carriers of 5 taxa of periplocaceaesensu stricto are described. These are ill organised inCryptolepis andCryptostegia and well organised inDecalepis andHemidesmus. The pollen tetrads are free in the former two taxa but organised into massulae in the latter. In their pollen carriersDecalepis andHemidesmus appear to connect periplocaceae with Secamonoideae of Asclepiadaceae.

    • Embryogenesis in sexual and asexual species ofZeuxine (Orchidaceae)

      K Ananda Karanth B G L Swamy Govindappa D Arekal

      More Details Abstract Fulltext PDF

      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.

    • A new Brachystelma (Asclepiadaceae) from Kolar, Karnataka

      Govindappa D Arekal T M Ramakrishna

      More Details Abstract Fulltext PDF

      Brachystelma kolarenses Arekal et Ramakrishnasp. nov., (Asclepiadaceae) collected from Kolar district, Karnataka State, is described with illustrations.

    • Embryology ofMicrargeria wightii Benth. (Scrophulariaceae)

      H G Vijay Gopalraj Urs Govindappa D Arekal

      More Details Abstract Fulltext PDF

      The anther is tetrasporangiate. The young microsporangium wall comprises of an epidermis, a fibrous endothecium, a middle layer and a layer of glandular tapetum of binucleate cells. The tapetum is of dual origin and exhibits morphological dimorphism. The development of the female gametophyte conforms to the Polygonum type. An endothelium surrounds the middle part of the embryo sac at maturity. The endosperm isab initio cellular. The chalazal haustorium is single-celled and binucleate. The micropylar haustorium is highly aggressive. To begin with it has two binucleate cells, which subsequently fuse forming a single-celled, quadrinucleate bulbous body. Branched hyphalike tubular processes extending down along the conducting strand of the developing seed reaching almost the chalaza arise from it. The development of the embryo conforms to Crucifer type. The mature seed coat consists of 2–3 layers of cells together with the degenerating remains of the endothelium. The systematic position of the tribe Gerardeae in the subfamily Rhinanthoideae has been evaluated on embryological grounds.

  •  

© 2021-2022 Indian Academy of Sciences, Bengaluru.