Yellow Waterlily Research Articles

Pressurized Ventilation in the Yellow Waterlily

Current models of gas transport in aquatic plants hold that gases diffuse in an essentially static gas phase within the lacunae according to gradients in their individual partial pressures. This study introduces a new model of gases gas transport wherein the gases move through waterlilies in a mass flow. The internal gas spaces in Nuphar constitute a pressurized flow—through system, with ambient air entering the youngest emergent leaves against a small gradient in total gas pressure. This pressurization phenomenon is the result of purely physical processes driven by the gradients in temperature (thermal transpiration) and water vapor (hygrometric pressure) between the atmosphere and the lacunae of the youngest emergent leaves. The lacunae are continuous throughout the entire plant, and the older leaves vent the elevated pressure generated by the younger leaves. This arrangement gives rise to a flow—through pattern, accelerating both the rate of O2 supply from the atmosphere to the roots, and the rate of CO2 and CH4 transport from the roots towards the atmosphere. This ventilation system represents an important adaptation by the waterlily to life in anaerobic sediments.

Accumulation of copper in fluvial sediments and yellow water lilies (Nuphar lutea) at varying distances from a metal processing plant.

Accumulation of copper in fluvial sediments and yellow water lilies (Nuphar lutea) at varying distances from a metal processing plant.

The relationship between temperature and duration of egg development in some epiphytic cladocera and copepoda from the River Thames, reading, with a discussion of temperature functions.

Data on the duration of egg development at 5, 10, 15 and 20°C are given for eight cladoceran and one cyclopoid copepod species found associated with the Yellow Water Lily (Nuphar lutea) in the River Thames. A decrease in temperature caused a marked increase in the time taken to complete development for all nine species. The data are compared with published data and a number of conclusions drawn. In general, cladoceran eggs tend to take longer to complete development than copepod eggs, and within the Cladocera the eggs of epiphytic species tend to take longer to develop than those of planktonic species, and the eggs of large species longer than the eggs of small species.The relationship of development time to temperature was examined, and the linear reciprocal relationship, Krogh's curve and the vant' Hoff-Arrhenius function were found to be inadequate. Statistical analysis of the data required a logarithmic transformation, and this gave a significantly curvilinear relationship for all nine species. A quadratic of the form: logD = log a + b log T + c(logT)2 gave the best fit for eight of the species, but this could be reduced to log D = log a ´+c ´ (logT)2 with only a slight decrease in the predictive value of the model. A comparison of regression lines showed that the data for each species could only be described properly by individual regression lines for each species: common slope or common intercept lines, or a single line were not valid. A survey of the literature suggests that the analyses in many previous investigations are statistically inadequate. A critical discussion of temperature functions is given.

Control of Waterlilies with Dichlobenil

Early postemergence applications of 2,6-dichlorobenzonitrile (dichlobenil) granules at 15 lb/A controlled 97 to 99% of dwarf waterlily (Nymphaea tetragonaGeorgi) in a shallow lake for 3 years. Dichlobenil alone was superior to a combination of dichlobenil and (2,4-dichlorophenoxy)acetic acid (2,4-D) for the control of dwarf waterlily and western yellow waterlily (Nuphar polysepalumEngelm). Reinfestation was more rapid on plots 25 by 25 ft in size than on plots 50 by 50 ft in size. When a high degree of control was maintained for 2 or 3 years, rhizomes of dwarf waterlily and a 1 to 2-ft layer of hydrosoil floated to the lake surface 17 months after dichlobenil was applied.

Rufford Village Museum

RUFFORD Village Museum, which was opened at Rufford Old Hall, a National Trust property in West Lancashire in July of last year as: “A Museum of Folk Culture and Industry: To illustrate and capture the spirit of the countryside” (to quote its constitution) is being developed by the honorary curator, Mr. Philip Ashcroft, jun., to be “an example for other districts to follow, so that in the future, each village or group of villages will have a museum to represent their life, history and culture”. In addition to Baron Hesketh's extensive collection of old armoury and other relics of medieval life, Mr. Eric Hardy has drawn up lists of the local fauna and flora which will be exhibited above photographs, drawings, diagrams, etc., of wild life to encourage people to preserve as well as observe the wild life of the parish. This happens to be unusually rich, for the flora includes flowering rush, flowering fern, arrowhead, yellow waterlily, water soldier, bladderwort and nearly a thousand other plants; there is a list of twenty-two mammals for the parish and F. A. H. Hall and E. Hardy have drawn up a list of 101 bird records, including sixty nesting species—a third of the British records. The Museum itself is a historic old timbered hall, the restored part of which dates from the seventeenth century.