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41.
MANUEL B. CRESPO ANTONIO DE LA TORRE JOSE L. SOLANAS 《Botanical journal of the Linnean Society. Linnean Society of London》1994,116(2):135-144
Linaria arabiniana sp. nov. is described from coastal sand dunes of a very reduced area in Alicante Province (south-eastern part of the Iberian Peninsula). It is a perennial herb characterized by its 3–4-verticillate leaves, glabrous stems, large violet or rarely yellow flowers, and bicoloured usually flat seeds. Morphological characteristics and taxonomic affinities of this taxon are discussed, as are data on its ecology, phytosociology, and eventual conservation features. 相似文献
42.
Multi‐gene phylogeny of the Hemileuca maia complex (Saturniidae) across North America suggests complex phylogeography and rapid ecological diversification
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The Hemileuca maia species complex occurs across the North American continent and consists of six named taxa, and several others that were recently synonymized. Taxa exhibit a wide span of adult flight periods, dramatic shifts in host‐plant use and occur in a range of habitats, all of which would suggest unrecognized diversity. We used one mitochondrial and three nuclear genes to generate 3900 bp per individual, including samples from every ecotype in the species group across the United States from New England to central Florida to California. We assessed phylogenetic relationships using both maximum likelihood and Bayesian phylogenetic methods. Results suggest very low levels of divergence across most of the continent and low levels of genetic structure – even between some recognized species that maintain clear ecological difference in sympatry. Our results suggest that meaningful and localized ecological divergence may occur in the absence of easily recognizable genetic divergence, due to either ongoing gene flow or the recent diversification in the group. 相似文献
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Trypsin Inhibitors during Germination of Vigna sinensis Seeds 总被引:2,自引:0,他引:2
JOSE XAVIER FILHO 《Physiologia plantarum》1973,28(1):149-154
The trypsin inhibiting activity of cotyledonary extracts of serido beans (Vigna sinensis) falls continuously during germination to a value which represents 5 % of the value for the dry seed. The specific activity is constant over the first three days and then decreases, reaching a level at the seventh day of germination which represents 20 % of the initial value. It is also shown that the axial parts control the disappearance of the trypsin inhibiting activity of the cotyledons. The results presented here seem to indicate a role for these substances in the process of germination. 相似文献
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This study compared the performance of the stable isotope composition of carbon (δ13C), oxygen (δ18O) and nitrogen (δ15N) by tracking plant response and genotypic variability of durum wheat to different salinity conditions. To that end, δ13C, δ18O and δ15N were analysed in dry matter (dm) and the water‐soluble fraction (wsf) of leaves from plants exposed to salinity, either soon after plant emergence or at anthesis. The δ13C and δ18O of the wsf recorded the recent growing conditions, including changes in evaporative conditions. Regardless of the plant part (dm or wsf), δ13C and δ18O increased and δ15N decreased in response to stress. When the stress conditions were established just after emergence, δ15N and δ13C correlated positively with genotypic differences in biomass, whereas δ18O correlated negatively in the most severe treatment. When the stress conditions were imposed at anthesis, relationships between the three isotope signatures and biomass were only significant and positive within the most severe treatments. The results show that nitrogen metabolism, together with stomatal limitation, is involved in the genotypic response to salinity, with the relative importance of each factor depending on the severity and duration of the stress as well as the phenological stage that the stress occurs. 相似文献
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EDWARD E. SCHILLING JOSE L. PANERO 《Botanical journal of the Linnean Society. Linnean Society of London》2002,140(1):65-76
Results for nuclear ITS sequences were combined with previously obtained data from cpDNA restriction site studies to provide a comprehensive molecular phylogeny for subtribe Helianthinae. Results from the two molecular data sets were mostly congruent for basally diverging branches of the subtribe. Based on the results, combined with morphological observations, the basally diverging branches are placed in six genera, including one newly described. Bahiopsis is resurrected to accommodate species previously placed in Viguiera subgenus Bahiopsis . Calanticaria is newly proposed for the five species of Viguiera ser. Brevifolieae . Heliomeris is retained for the group sometimes included within Viguiera as sect. Heliomeris . Hymenostephium is revived and enlarged to include a number of species of similar habit and involucre, including members of Viguiera sect. Diplostichis , Haploca-lymma and Garcilassa . Although cpDNA results place the morphologically distinctive Sclerocarpus within the clade including species of Hymenostephium , the ITS data were consistent with morphology in suggesting it to be a distinctive lineage. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 65–76. 相似文献
50.
Carbon Dioxide and Ammonia Exchange in the Trachypogon Savannas of the Orinoco Llanos 总被引:1,自引:0,他引:1
Atmospheric carbon dioxide (CO2) and ammonia (NH2) exchangeswere determined in the Trachypogon savannas of the Orinoco Llanosusing the energy balance approach. Total dry mass and separatedry mass values of plant parts were used for a growth analysisof the community and for measurements of nitrogen content. Duringthe growth period, the net assimilation (P40) ranged from 0.102to 0.127 MJ m2 d1 (6.67.9 g dry mass m2d1). These figures were similar to mean crop growth ratemeasured using the mass balance approach (2.86.9 g drymass m2 d1). Analysis of the daily trend of theCO2 assimilated by the community showed a low total energy conversionof net photosynthesis (x = 0.7) compared with the values reportedfor tropical grasses. During the dry season, the community conserved71% of the maximum N accumulated during the previous wet season.Sixty-eight per cent of the community nitrogen content was lostas volatile NH3 from the community during the reproductive period.Results suggested that the predominant net NH3 efflux from thevegetation was determined by the low concentration of NH3 inthe atmosphere ( 1.8 µg m2) and the compensationconcentration point. However, N losses were balanced by annualnitrogen input to the community from precipitation and biologicalfixation. Thus, a redistribution rather than a loss of nitrogenseems to be occurring in the ecosystem. Carbon dioxide fluxes, ammonia fluxes, Trachypogon savannas, energy balance, growth analysis 相似文献