Novedades florísticas y corológicas para la provincia de Córdoba (España)

Se comentan 13 taxones de plantas vasculares de interés para la flora de Córdoba, ya sea porque se amplía significativamente su conocimiento corológico en la provincia [Isoetes velatum A. Braun subsp. velatum, Marsilea strigosa Willd., Phytolacca americana L., Rumex palustris Sm., Carum verticillatum (L.) W. D. J. Koch, y Holcus mollis L.], se confirma su presencia (Lupinus micranthus Guss.) o bien son novedad para el territorio [Armeria linkiana Nieto Fel., Limonium sinuatum (L.) Mill., Maclura pomifera (Raf.) C. K. Schneid., Schoenoplectus erectus (Poir.) Palla ex J. Raynal, y Cenchrus longisetus M. C. Johnst.]. En el caso de Eryngium caespitiferum Font Quer & Pau, su nueva recolección respalda la primera cita dada a conocer para Europa. Todos los pliegos-testimonio se encuentran depositados en el Herbario de la Universidad de Córdoba (COFC).Floristic and chorologic novelties for the Flora of Cordoba provincePalabras clave: Flora vascular, Corología, Córdoba.Key words: Vascular flora, Chorology, Córdoba.

Photosynthetic response of mountain grassland species to drought stress is affected by UV-induced accumulation of epidermal flavonols

Interactive effects of drought and ultraviolet (UV) radiation on CO2 assimilation rate and accumulation of epidermal flavonols were studied in two herbs (Hypericum maculatum and Rumex obtusifolius) and two grasses (Agrostis capillaris and Holcus mollis) under field conditions of Beskydy Mts. The main objective of this study was to evaluate a protective role of epidermal flavonols against drought stress. Experimental shelters were used to manipulate amount of incident precipitation and UV radiation intensity for 12 weeks (May–July). The light-saturated CO2 assimilation rate (Amax) and the content of epidermal flavonols were regularly measured at intervals of 2–3 weeks during the entire period. Drought-induced reduction of Amax was enhanced by high UV intensity in R. obtusifolius, whereas in other species UV radiation reduced a negative effect of drought. Generally, drought increased flavonol content in leaves as compared to non-stressed plants. Similarly, high UV intensities increased the flavonol content in control plants, but not in drought-stressed ones. Regression analysis between the flavonol content and Amax revealed a positive correlation especially for A. capillaris and R. obtusifolius. In both species, a separation of these relationships was observed as the result of water availability. Thus lower Amax were observed at the same flavonol content in drought-stressed plants when compared to control, well-watered counterparts. We conclude that UV-induced accumulation of epidermal flavonols can alleviate negative impacts of summer drought on photosynthesis, particularly in species with slower ontogeny like H. maculatum and A. capillaris.

Post-fire succession on abandoned fields in coniferous forest habitat (Nord-East Poland)

In July, 1992, fire swept through the Jelonka Reserve (52^o35'33"N; 23^o22'10"E). Litter, herbs layer and juniper shrubs were razed and the tree trunks of <em>Pinus sylvestris</em> and <em>Populus tremula</em> damaged, which resulted in their death the following year. Five research plots of 25 m² each were established in the post-fire area. The species present there and their degrees of coverage were listed on the Londo scale between 1993 and 2002. The calculation of average degrees of coverage for individual populations allowed for the establishing of a chronological pattern of post-fire succession. The following findings have been made: 1) the primary function in colonization belongs to species of guerilla strategy of growth whose dormant buds survived fire underground (<em>Holcus mollis</em>, <em>Calluna vulgaris</em> and <em>Populus tremula</em>) or phalanx strategy of growth (<em>Corynephoms canescens</em>); 2) the dominants of the initial succession stage are perennial grasses, not therophytes; 3) the spatial pattern of succession is influenced by the occurrence of <em>H. mollis</em> or <em>C. canescens</em> in a particular location; 4) the initial stage terminates with the occurrence and further growth of <em>C. vulgaris</em> clumps; the post-fire succession in the Jelonka Reserve attained a brushwood stage faster in comparison to secondary succession, formerly triggered by the cessation of cultivation on arable land.

Das cyanogene Glykosid von Holcus mollis / The Cyanogenic Glycoside of Holcus mollis

From leaves of Holcus mollis L. the structure of the cyanogenic glycoside could be elucidated as 2-β-ᴅ-glucopyranosyloxy- 2S-butyronitrile (Heterodendrin) by means of chromatography, hydrolysis and 1H-NMR-spectroscopy. By that another example for grasses is given where obviously the general assumed biogenetic pathway starting with tyrosine is not used