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In This Issue |
Acomastylis rossii, the alpine avens, is the most common and abundant plant found above treeline in the southern Rockies, but it spends a long time below ground first. Leaves and flowers develop underground for two years before emerging for photosynthesis or reproduction. Thus, a total of three years are required for the complete development of these structures. Meloche and Diggle document preformation in this species and report several new and important observations: the extent of continued development below ground in the autumn and the increased potential to respond to environmental change offered by the particular architecture of this species. Their excellent morphological and phenological description of this common alpine perennial is a significant contribution to the nascent field of developmental ecology. (see p. 980)
C4 syndrome in Cyperaceae: multiple origins
Soros and Dengler contribute significantly to our understanding of cellular structure-function relationships in the leaves of C3 and C4 plants, specifically those of Cyperaceae, for which little information is known. Because the C4 syndrome has evolved independently numerous times, in many taxonomic groups, identifying the common or unique developmental events that build each of these evolutionarily distinct C4 leaves is interesting and illuminating. In this study, cell lineage patterns of photosynthetic tissues and immunolocalization of cell-type-specific enzymes were used to characterize development of the C4 syndrome in three of the four anatomical types. Although all share a general developmental pattern, there are subtle differences among the lineages, presumably reflecting their separate evolutionary origins. (see p.992)
Mis-predicting temperature from toothed fossil leaves
Burnham et al. consider the issue of paleoclimatic reconstruction from fossil leaf assemblages. The paper specifically addresses the variability of estimates of mean annual temperature derived from different forest types growing under a single climatic regime. They found that along a river in western Amazonia there were more species bearing toothed leaves than in adjacent upland forests. Burnham et al. tested and confirmed this observation with data from plant inventories of lacustrine, riparian, and nonriparian forests. As the authors indicate, it will be important to determine whether the pattern observed in western Amazonia is replicated elsewhere, such as Asia and North America, where the standard databases were first developed. Because fossils are often deposited in wetlands like rivers, swamps, and lakes, the bias created by using calibration data from terra firme forests merits further investigation. (see p. 1096)
Weeds mitigate methane emission in paddy fields
Rice paddy fields are one of the dominant anthropogenic sources of methane (one of the "greenhouse" gases) emission to the atmosphere. Inubushi et al. report that the presence of aquatic weeds in a rice field lowers the overall methane emission from the field. More than double the amount of methane was emitted from weeded plots compared with unweeded plots. The methane oxidation activity of roots from three typical aquatic weeds in paddy fields was higher than that of rice plants. Thus, the role of aquatic weeds should not be overlooked in evaluating mitigation options for reducing methane emission from paddy fields. (see p. 975)
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