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1

The influence of standing vegetation height on the reproductive allocation In populations of Serratula tinctoria L. (Asteraceae)

100%
Kostrakiewicz-Gieralt K., Baba W.
Polish Journal of Ecology
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2014
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tom 62
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nr 1
The advantage of the clonal plants over the nonclonal species in colonization of all biomes and biogeographical regions primarily is due to occurrence of two modes of reproduction. The creating of vegetative propagules with high vitality and survivability, enables the spread in the newly colonized site, while seed production increases the chances for successful recruitment of seedlings, ensuring the genetic diversity of the population. The differences in allocation into vegetative reproduction and generative propagation in relation to rising height of adjacent plants was investigated in populations of Serratula tinctoria L., occurring in Molinietum caeruleae meadows localized in Southern Poland. Each locality was represented by randomly established three permanent study plots: dominated by small meadow species (LOW), prevailed by large-tussock grasses (INTER) and overgrown by shrubs and trees (HIGH). In the years 2009–2011 the number of leaf rosettes and length of the longest leaf in rosette (as a measure of allocation in vegetative propagation), as well as height of generative stems, number of capitula per stem and number of seeds per capitulum (as indicators of investment in generative reproduction) were observed. The allocation in vegetative reproduction decreased along the gradient of vegetation height. The gradually decline of number of rosettes might be caused by lack of free space suitable for establishment of new ramets, whereas the small leaf size could be due to drastically augmentation of shading. The allocation in generative reproduction increased along the gradient of vegetation height. The placement of structures necessary for generative propagation in higher layers of herbaceous canopy, as well as considerable number of capitula and seed production might increase the chances for successful recruitment of seedlings. On the basis of obtained results combining with published data it should be assumed, that the substantial allocation in vegetative reproduction and the slight investment in generative propagation seems to be sufficient for persistence of Serratula tinctoria populations in patches dominated by small meadow species, while the considerable allocation in generative reproduction could be crucial for maintenance of population viability under competitive conditions.
2
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Germination of Matricaria maritima subsp. Inodora [L.] dostal [scentless mayweed] achenes depending on their maturity and position on the mother plant

84%
Kucewicz M., Holdynski C.
Journal of Plant Protection Research
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2003
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tom 43
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nr 2
3

On corniculi, rutella and pseudorutella - some ultrastructural details of key-characters in Acari [Arachnida]

84%
Alberti G.
Annales Zoologici
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2008
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tom 58
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nr 2
The gnathosoma is considered by most authors as the main constitutive character of a monophylum Acari. However, this has been questioned due to fundamental differences regarding its morphology in Anactinotrichida (=Parasitiformes s.l.) and Actinotrichida (=Acariformes). A key character which might indicate homology is represented by stout cuticular structures called corniculi, rutella, and/or pseudorutella present in most of the main groups of mites. However, the homology of these structures has also been doubted. In the present paper a first comparative ultrastructural study on these elements is presented taking representatives of all main groups of Acari in consideration (except of ticks lacking these structures). It was shown that the structures under concern are quite different even in closely related taxa. Hence the question on homology could not be solved definitely. Evidently more studies are needed to elucidate this problem.
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