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MARKUS RUHSAM RAFAEL GOVAERTS AARON P. DAVIS fls 《Botanical journal of the Linnean Society. Linnean Society of London》2008,157(1):115-124
During the preparation of a World Rubiaceae Checklist , numerous unplaced taxa were encountered, including illegitimate and invalid names, and species for which generic placement is uncertain. In this contribution, 35 new combinations and 20 new names are proposed, and the names of three taxa are validated. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 115–124. 相似文献
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Plants that hyperaccumulate Ni contain > 1000 ppm (dry wt.) in their tissues. Variation of Ni content within hyperaccumulating plant species is poorly explored. Using the Ni-hyperaccumulating shrub Psychotria douarrei, we documented variation of leaf Ni levels within individual shrubs, and variation with respect to plant size and leaf age. Plant size did not correlate significantly with leaf Ni content, and leaf Ni content did not correlate significantly with soil Ni content. Older leaves contained twice as much Ni as younger leaves. Older leaves also contained greater concentrations of Ca, Fe, and Cr but less K, P, and Cu. Five elements (Zn, Pb, Co, Mn, Mg) showed no significant variation due to leaf age. We also examined the effect of leaf age on epiphyll cover, finding increased epiphyll cover on the upper surface of older leaves. The dominant leafy liverwort epiphyll had a relatively high Ni content (400 ppm), suggesting that epiphylls of Ni hyperaccumulators obtain some Ni from host leaves. Individual shrubs differed in mean leaf Ni content almost two-fold (14,900-27,700 ppm). Variation among branches within individuals also ranged widely; however, this intraplant variability was not strongly correlated with the mean leaf Ni content of an individual shrub. We concluded that Ni contents in leaves of P. douarrei vary considerably due to leaf age, among individual shrubs, and among branches within a shrub. 相似文献
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The geophytoelectrical current of three evergreen tropical tree species is studied as an indirect measure of their relative
water content. Two intermediate shade-tolerant species (Aphananthe monoica and Pleuranthodendron lindenii), distributed in the middle and upper canopy strata, and an understory shade-tolerant species (Psychotria costivenia) were examined. The annual rhythm of geophytoelectrical currents per cm of diameter (DBH) is seasonal, with the highest occurrence
in the winter and summer. There is a significant association between maximum temperature, moisture in the environment, and
geophytoelectrical current per cm of DBH in the three species, as shown by multiple regression analysis. This finding suggests
the existence of various geophytoelectrical current patterns which differs from that reported for temperate species. 相似文献
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Heterostyly is a genetically controlled floral polymorphism usually associated with an incompatibility system. This set of
features is known to occur in several angiosperm families, but some aspects of its biology has not been well studied. The
present study investigates cellular aspects of the pollen–pistil interaction after compatible and incompatible pollinations
of Psychotria nuda, to increase our knowledge of heteromorphic self-incompatibility (HetSI). The use of bright field, fluorescence and transmission
electron microscopy methods allowed us to demonstrate that pollen tubes behave differently after incompatible and compatible
pollinations. Pollen tubes were particularly distinct after incompatible pollinations of L- and S-morph flowers. Relative
to compatible pollen tubes, incompatible L-morph tubes had a drastic reduction in cellular contents, but no cell rupture.
Incompatible S-morph tubes exhibited dense cytoplasm in apical regions, as well as in other regions, accompanied by a rupture
of the apex. These results support the hypothesis that L- and S-morph flowers have different incompatibility mechanisms during
HetSI. 相似文献
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Clonal diversity and conservation genetics of the medicinal plant Carapichea ipecacuanha (Rubiaceae)
de Oliveira LO Venturini BA Rossi AA Hastenreiter SS 《Genetics and molecular biology》2010,33(1):86-93
The roots of the understorey shrub Carapichea ipecacuanha (ipecac) have medicinal properties, and the uprooting of wild plants has supplied most of the world demand for this species. Although under severe population decline, C. ipecacuanha lacks legal protection. In the wild, the aerial stems of ipecac clump together to form clusters with well-defined borders. Cluster size may range from several to hundreds of aerial stems. To investigate the extent of clonality among aerial stems in ipecac clusters, we sampled 50 wild clusters (a total of 291 aerial stems) and screened them with 89 inter-simple sequence repeat (ISSR) markers. The 291 aerial stems were grouped into 42 putative clones. The clonal groups generally consisted of aerial stems from the same cluster, and there was little or no genetic differentiation among aerial stems at the cluster level. These findings suggest that strategies designed to conserve ipecac in situ should not rely upon census data, which are based on the number of aerial stems per cluster and the number of clusters per population, because such data greatly underestimate the species effective population size and genetic diversity. Our results also indicate that this species needs protection at a federal level. 相似文献
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通过对广东中部的阳生性灌木桃金娘和阴生性灌木九节的形态学、解剖学、植物生态学以及植物生理学等方面的比较发现:处于强光照下的桃金娘通过大的根系、多的枝叶和小的叶片在水分和养分竞争中处于优势,并利用小的枝角和叶毛来避免强光的伤害,而九节则是通过其叶、枝的最经济数量和最佳位置排列来充分利用阴暗不足的光线;桃金娘通过叶片和栅栏组织厚度以及短的小脉间距在强光下能继续进行光合作用并尽快运出光合产物,而九节的叶片则可充分利用森林底层有限的光照;在南亚热带,30%左右的透光率是林下耐荫性树种九节入侵和阳生性灌木桃金娘消亡的辐射条件;九节的生态对策为K对策,而桃金娘遵循r对策;九节和桃金娘的平均光合速率分别为5.9±1.6μmol CO2·m-2·s-1和11.9±0.4μmol CO2·m-2·s-1,光补偿点分别为0.005和0.012mmol·m-2·s-1,光饱和点分别为0.04和0.39μmol CO2·m-2·s-1,气孔传导率分别为0.053±0.037μmolCO2·m-2·s-1和0.101±0.013 mol·m-2·s-l,暗呼吸速率分别为0.42±0.0lμmol CO2·m-2·s-1和0.16±0.15μmolCO2·m-2·s-1,这些生理学差异、形态解剖学差异等与其生境差异有密切的关系。 相似文献
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Michael Kiehn 《Plant Systematics and Evolution》1986,154(3-4):213-223
Chromosome numbers for 16 different taxa ofRubiaceae from Sri Lanka are presented. Counts for 13 species, including 5 genera and 1 tribe, are new. The results are listed, compared with available literature data and discussed in regard to their systematical importance. 相似文献
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