Aesculus flava (syn. A. octandra) is a species of buckeye native to eastern North America, from Pennsylvania, west to eastern Illinois, and south to the northernmost parts of Alabama and Georgia. Pollen dimorphism has been detected in anthers of some woody species. Uninuclear microspores isolated from closed flower buds in horse chestnut (R a d o j e v i c , 1989, 1991; C a l i c et al., 2003/4) and red chestnut (M a r i n k o v i c and R a d o j e v i c , 1992) showed differences in size, shape, staining intensity, fluorescence, viability, and embryogenic potential (R a d o j e v i c et al., 2000). Moreover, pollen orginating from 13 species of the genus Aesculus showed differences in size and shape, pore position, sculpturing of the colpal membrane, and sculpturing of the mesocolpia (P o z h i d a e v, 1995). The small yellow-green inflorescence of Aesculus flava is about 17 cm long and 7 cm wide. Composed of an upright panicle of many solitary flowers, it appears in mid-May, the inflorescence clearly rising above the expanded foliage. As in flowers of Aesculus hippocastanum, A. flava flowers located in the basal part of the panicle are female and fertile, while flowers in the middle are bisexual and those on the top are male (H e y w o o d , 1978).

Genetic variability within Serbian populations of the pottioid moss Hilpertia velenovskyi (Schiffn.) Zander was studied. Eight populations of this rare and endangered moss species were chosen for peroxidase isozyme analyses. From the data obtained, it can be inferred that four haplotypes are present among H. velenovskyi populations in Serbia, the Banat population being distinctive from all others.

The aim of this paper is the determination of air pollution influence on the percentage of stomata in tested woody species, horse chestnut and birch, under examined Banja Luka air pollution conditions. Two locations in Banja Luka town were examined, with different air pollution degrees: the first location is a hostel for students, with the minimal or absent air pollution; the second location is the west transit, with high air pollution due to a high number of motor cars which pass by the west transit. The air pollution difference between these two locations is very marked, and the objective of the examination was to assess how the indicated locations, which have different life conditions for the tested woody species, impact the physiological processes such as transpiration and photosynthesis. The study species react differently when the percentage of stomata and air pollution are compared.