The aim of this study was to investigate the floristic composition and diversity of seven urban habitat types in 24 Serbian cities with different climatic affiliation. In each of the 24 cities, we selected 1 ha plots representing a habitat from one of the following groups: square, boulevard, residential area with compact and with open building pattern, city park, and sites with early and mid-succession vegetation stages. All vascular plant species that occur spontaneously in these plots were observed. Data on the main climatic characteristics were collected for each plot, and data on the life forms were obtained for each species recorded. Diagnostic species were identified for each habitat type analyzed, and alpha, beta and gamma diversity were calculated. A total of 674 taxa were recorded in the studied area. Significant differences were observed in habitats by diagnostic species and by life form representation. The lowest alpha and gamma diversity and the dominance of therophytes were observed in habitat types with intensive anthropogenic impact, whereas the highest number was recorded in mid-successional sites and residential areas with a compact building pattern. The analysis showed that habitat type influences species composition much more than climate.

Serpentine substrate in Serbia covers wide areas mainly in Kosovo and in central, western and south-western part of the country. On the serpentines of Serbia, particularly on the skeleton soils of hills and on lower elevation mountain slopes, there are some xerophilous and steppe-like vegetations. These xerophilous grasslands include mostly Pontic, Pontic-Submediterranean and/or Mediterranean-Submediterranean-Pontic plants. The distribution of 161 taxa of Pontic, Pontic-Submediterranean and Mediterranean-Submediterranean-Pontic areal — types on serpentinites of Serbia was analyzed in order to distinguish centers of richness and diversity. The distribution of taxa was analyzed with respect to geographic, ecological and climatic factors. The qualitative composition of Pontic flora on the serpentine areas was also compared. The greatest floristic richness and the center of diversity of Pontic flora on serpentine of Serbia was recorded in central part of the area investigated.

The paper propose nine new nomenclature combinations and indicate eight new synonyms. There are 12 taxa (species and subspecies) of vascular flora which are new for the flora of Serbia (of which nine are autochthonous and three 88 N iketić, M. etal. : Annotated Checklist of Vascular Flora of Serbia II allochtonous plants). An old or unreliable literature records for three autochthonous and one allochthonous plant in the flora of Serbia has been confirmed. Eight plant taxa are a novelty for proper Serbia, Vojvodina, or Kosovo and Metohija, and for three plants, presence in certain administrative units in Serbia has been proved. The last part of the paper contains information on eight taxa whose presence in Serbia or in its territorial units has been refuted.

This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: diatoms Discostella asterocostata and Stephanodiscus hantzschii f. tenuis, red alga Bangia atropurpurea, green alga Ulva pilifera, saprotrophic fungi Didymella vitalbina and Phragmotrichum rivoclarinum, mosses Buxbaumia aphylla, Sphagnum divinum, and Tortella fasciculata, monocots Anacamptis × nicodemi, Epipactis palustris, Epipogium aphyllum, and Gymnadenia frivaldii and dicots Androsace lactea, Drosera rotundifolia, Potentilla montenegrina, and Tozzia alpina subsp. carpathica are given within SE Europe and adjacent regions.

The high diversity of ruderal vegetation in urban environments is well known. Although it has been a subject of numerous studies in Serbia, in recent years it has been slightly overlooked, although, due to the dynamics of ruderal habitats, constant research is required. We investigated ruderal vegetation in 20 cities across Serbia during a period of 5 years. Most of the relevés were collected during the summer months, and within 712 relevés, 422 taxa were recorded. Results of the cluster analyses and identified diagnostic species revealed 26 plant communities, of which nine are dominated or co-dominated by aliens. The relevés can be grouped into six ecologically well-differentiated major vegetation groups. Our study revealed the ruderal communities which are the most widespread in urban environments in Serbia. Additionally, some communities were registered for the first time in the country.