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Longer Leaves (longer + leaf)
Selected AbstractsNew taxa of Allium L. subg.FEDDES REPERTORIUM, Issue 7-8 2008Allium (Alliaceae) from Tajikistan, Uzbekistan The alliances of Allium filidens Regel and A. brevidens Vved. were taxonomically revised. Three subspecies were recognized for A. filidens. The widely distributed typical subspecies is characterized by thick reticulate bulb tunics, relatively short leaf sheathes, and whitish tepals with greenish or bluish median veins. Subspecies ugamicum (Vved.) R.M.Fritsch & F.O.Khass. occurring in Chatkal, Pskem, and Ugam mountain ranges E and NE of Tashkent, has delicate, reticulate bulb tunics, relatively longer leaf sheathes, and faintly blue to violet flowers. Subspecies mogianense R.M.Fritsch & F.O.Khass. occupies a small area of distribution in western Hissar mountain range and differs from subsp. ugamicum by greenish tepals with broad green median veins. A key for determination of these subspecies is given. Allium brevidens subsp. pshikharvium R.M.Fritsch & F.O.Khass. was newly described from higher altitudes of Tajik Vanch, Darvaz, and Peter I. mountain ranges. It differs from the typical subspecies by larger scapes, denser inflorescences, green (not yellowish) tepals with dark-green median veins and violet (not purplish) filaments. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Neue Taxa von Allium L. subg. Allium (Alliaceae) aus Tadschikistan und Usbekistan Die Verwandtschaftskreise von Allium filidens Regel and A. brevidens Vved. umfassen jeweils mehrere Unterarten. Die typische Unterart von A. filidens ist weit verbreitet und besitzt dicke, reticulate Zwiebelhüllen, relativ kurze Blattscheiden und weißliche Tepalen mit grünlichem oder bläulichem Mittelnerv. Pflanzen aus den Gebirgen im Norden und Nordosten von Taschkent haben sehr zarte reticulate Zwiebelhüllen, relativ längere Blattscheiden und blaßblaue bis violette Blüten. Sie werden als subsp. ugamicum (Vved.) R.M.Fritsch & F.O.Khass. neu kombiniert. Die neu beschriebene subsp. mogianense R.M.Fritsch & F.O.Khass. ist nur aus dem westlichen Hissar-Gebirge bekannt und unterscheidet sich von subsp. ugamicum durch grünliche Tepalen mit breitem grünem Mittelnerv. Ein Schlüssel der Unterarten wird präsentiert. Aus höheren Gebirgslagen in Tadschikistan wird A. brevidens subsp. pshikharvium R.M.Fritsch & F.O.Khass. neu beschrieben, das sich von der typischen Unterart durch längere Schäfte, dichtere Blütenstände, grüne (nicht gelbliche) Tepalen mit dunkelgrünem Mittelnerv sowie violette (nicht purpurne) Filamente unterscheidet. [source] Effects of four generations of density-dependent selection on life history traits and their plasticity in a clonally propagated plantJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2003M. Van Kleunen Abstract Life history evolution of many clonal plants takes place with long periods of exclusively clonal reproduction and under largely varying ramet densities resulting from clonal reproduction. We asked whether life history traits of the clonal herb Ranunculus reptans respond to density-dependent selection, and whether plasticity in these traits is adaptive. After four generations of exclusively clonal propagation of 16 low and 16 high ramet-density lines, we studied life history traits and their plasticities at two test ramet-densities. Plastic responses to higher test-density consisted of a shift from sexual to vegetative reproduction, and reduced flower production, plant size, branching frequency, and lengths of leaves and internodes. Plants of high-density lines tended to have longer leaves, and under high test-density branched less frequently than those of low-density lines. Directions of these selection responses indicate that the observed plastic branching response is adaptive, whereas the plastic leaf length response is not. The reverse branching frequency pattern at low test-density, where plants of high-density lines branched more frequently than those of low-density lines, indicates evolution of plasticity in branching. Moreover, when grown under less stressful low test-density, plants of high-density lines tended to grow larger than the ones of low-density lines. We conclude that ramet density affects clonal life-history evolution and that under exclusively clonal propagation clonal life-history traits and their plasticities evolve differently at different ramet densities. [source] Selection on apomictic lineages of Taraxacum at establishment in a mixed sexual,apomictic populationJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2000De Kovel A species' mode of reproduction, sexual or asexual, will affect its ecology and evolution. In many species, asexuality is related to polyploidy. In Taraxacum, apomicts are triploid, and sexuals are diploid. To disentangle the effects of ploidy level and reproductive mode on life-history traits, we compared established apomictic Taraxacum genotypes with newly synthesized apomictic genotypes, obtained from diploid,triploid crosses. Diploid,triploid crossing is probably the way that most apomictic lineages originate. New genotypes had on average a much lower seed set than established genotypes. Established genotypes differed on average from new genotypes, in particular under shaded conditions: the established genotypes had longer leaves and flowered later. The differences between new and established triploids resembled the differences that have been found between sexual diploids and established apomictic triploids. We conclude that ploidy differences alone are not directly responsible for observed differences between sexual diploid and apomictic triploid dandelions. [source] Contributions of disease resistance and escape to the control of septoria tritici blotch of wheatPLANT PATHOLOGY, Issue 5 2009L. S. Arraiano The contributions of disease escape and disease resistance to the responses of wheat to septoria tritici leaf blotch (STB) were analysed in a set of 226 lines, including modern cultivars, breeding lines and their progenitors dating back to the origin of scientific wheat breeding. Field trials were located in the important wheat-growing region of eastern England and were subject to natural infection by Mycosphaerella graminicola. STB scores were related to disease-escape traits, notably height, leaf spacing, leaf morphology and heading date, and to the presence of known Stb resistance genes and isolate-specific resistances. The Stb6 resistance gene was associated with a reduction of 19% in the level of STB in the complete set of 226 lines and with a 33% reduction in a subset of 139 lines of semidwarf stature. Greater plant height was strongly associated with reduced STB in the full set of lines, but only weakly in the semidwarf lines. Shorter leaf length was also associated with reduced STB, but, in contrast to earlier reports, lines with more prostrate leaves had more STB on average, probably because they tended to have longer leaves. Several lines, notably cvs Pastiche and Exsept, had low mean levels of STB which could not be explained by either escape traits or specific resistance genes, implying that they have unknown genes for partial resistance to STB. [source] | ||||||||||