• V Seshavatharam

      Articles written in Proceedings – Plant Sciences

    • A contribution to the embryology ofAlysicarpus monilifer D.C.

      V Seshavatharam

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      Embryology ofAlysicarpus monilifer D.C. is described. The anther wall comprises the epidermis, the fibrous endothecium, two middle layers and uniseriate glandular tapetum. Pollen is shed at the 2-celled stage. The ana-campylotropus ovule is crassinucellate and bitegmic. The archesporium in the ovule is hypodermal and cuts off a parietal cell. Embryo sac development conforms to the Polygonum type. Endosperm development is nuclear. A chalazal part of the endosperm remains free nuclear and is haustorial in function. Embryogeny conforms to Period I Megarchetype IV and Series B2. The embryogenic classification of the tribe is discussed in the light of the present observation and earlier reports.

    • Contribution to the leaf anatomy of the genusPennisetum Rich

      M Suryanarayana Raju V Seshavatharam S Appa Rao

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      Leaf epidermal patterns in 18 species belonging to the genusPennisetum Rich., were described. The variation in the leaf epidermal characters was utilized for the identification of species. Macro hairs were recorded only inPennisetum americanum, Pennisetum clandestinum, Pennisetum polystachyon, Pennisetum pedicellatum, Pennisetum villosum, Pennisetum cenchroides, Pennisetum purpureum × typhoides (hybrid) andPennisetum orientale. Short cells between the veins were paired, solitary or more than two celled. Prickle hairs were absent only inPennisetum polystachyon. Hooks were absent only inPennisetum hohenackeri andPennisetum squammulatum. Stomata with triangular subsidiary cells occur in all the species. Silica bodies are of various types. A dichotomous key was prepared based on epidermal characters for the identification of the different species studied.

    • Diurnal and seasonal variations in the phytoplankton production of lake Kondakarla

      K S N Murthy V Seshavatharam

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      Variations in the phytoplankton production of lake Kondakarla were estimated at two levels (surface and at 1 m depth) during a period of 12 months. The gross production values ranged from 0·10–1·40 mg O2l−1 h−1 at surface and from 0·06–0·73 mg O2l−1 h−1 at 1 m depth. Peak values of gross production occurred between 9–12 h or from 12–15 h during the different months at both the levels. The seasonal variation in gross primary production ranged from 2·70 mg O2l−1 day−1 during January 1984 to 9·42 mg O2l−1 day−1 in September 1983 for surface waters and from 1·60 mg O2l−1 day−1 during September 1983 to 5·40 mg O2l−1 day−1 in February 1984 in waters at 1 m depth. The depth intergrated production varied from 4·08–13·05 g O2m−2 day−1 while the photosynthetic efficiency ranged from 0·580–4·301%.

    • Decomposition studies on two floating leaved macrophytes,Nymphaea nouchali andNymphoides indica, of lake Kondakarla, India

      K S N Murty V Seshavatharam

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      Rates of weight loss and nutrient release (N, P, Ca, Mg, Na, K) were measured in decomposing tissues ofNymphaea nouchali Burm (leaf and rhizome) andNymphoides indica (L.) O Kuntze under field (90 days) and laboratory (60 days) conditions. Dry weight loss followed the sequence ofNymphoides indica>Nymphaea nouchali leaf >Nymphaea nouchali rhizome. The rate of nutrient release (N, P, Ca, Mg) from the decomposing tissues ofNymphaea nouchali rhizome appears to be correlated with nutrient concentration in leachate (receiving water) under laboratory experiments. The concentration of nitrogen in the decomposing tissues of all the samples increased with time. No increase in sodium and potassium concentrations was observed during the study under both the conditions. The maximum elemental loss was mostly observed under laboratory experiments than in the field studies. Accumulation of nitrogen, calcium and magnesium instead of release at certain stages of decomposition is attributed to microbial immobilization. The sequence of elemental loss in the decomposing tissues of these macrophytes is Na>K>P>Mg>Ca>N.

    • Systematic leaf anatomy of some Indian mangroves

      V Seshavatharam M Srivalli

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      Leaf anatomy of 13 species of Indian mangroves belonging to 11 genera and 9 families of the dicotyledons is presented. Leaves are dorsiventral in all the species except inLumnitzera racemosa where they are isobilateral and amphistomatic. The cells of the lower epidermis are larger than those of the upper surface. Stomatal type and size are considered. Water storage tissue is present in all the species exceptAegialitis rotundifolia. The significance of the findings are highlighted in light of the earlier available information and a key is constructed based on the leaf anatomical characters.

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