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This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: parasitic fungus Antherospora hortensis, saprotrophic fungi Loweomyces fractipes and Pholiota henningsii, stonewort Chara canescens, mosses Grimmia caespiticia and Rhodobryum ontariense, fern Woodsia alpina, monocots Aegilops triuncialis, Epipactis purpurata, Galanthus elwesii and Typha shuttleworthii and dicot Umbilicus luteus.

Halacsya sendtneri (Boiss.) Dorfl. is an obligate serpentine palaeoendemic of the Balkan Peninsula. It is able to maintain a favourable magnesium:calcium (Mg:Ca) ratio throughout its root and shoot, and grow in serpentine habitats with different microclimate conditions. Seasonal variation of leaf chlorophyll and carotenoid contents showed a steep decline right after the spring period, which was most probably caused by the drought imposed on the plants on the shallow serpentine soil. However, the in situ photosynthetic rate remained stable throughout the spring and summer period. Prolonged photosynthetic activity enables this species an investment into root development and sustainable survival in the harsh soils of the habitats it occupies.

To enhance understanding of edaphic conditions in serpentine habitats, a thorough investigation of the chemical and mechanical properties of three soils from disjunct ultramafic outcrops in the central Balkans was undertaken. Soil from a nearby chemically contrasting limestone habitat was also analyzed. Three plant species differently associated with serpentine habitats (Halacsya sendtneri, Cheilanthes marantae and Seseli rigidum) were references for site and soil selection. Twenty elements were determined, and fourteen were measured in seven sequentially extracted soil fractions. The quantified soil properties included pH, levels of free CaCO3, organic matter, P2O5, K2O, N, C, S, cation exchange capacity, total organic carbon, field capacity and soil mechanical composition. The usual harsh components for plant growth in serpentine soil, such as elevated Mg:Ca ratios, high levels of Ni, Cr or Co, were significantly lower in the available fractions. There was a significant positive correlation of organic matter and field capacity, with most available Ca (70-80 %) found in the mobile, rather than the organically bound fraction.

Serpentine (ultramafic) soils are extremely stressful environments for plant growth due to macronutrient deficiency (N, P, K, Ca), macronutrient toxicity (Mg; extremely high Mg:Ca ratio), and micronutrient toxicity (Mn, Fe, Ni, Cu, Zn), as well as toxicity of other heavy metals (Al, Cr, Co). Serpentine soils are also often shallow, rocky, and susceptible to drought. As a result of extreme adverse physical and chemical conditions, serpentine soils support a high proportion of endemic plant species that are adapted to their harsh environment. We analysed root, stem, and leaf tissue element concentrations (Ca, Mg, Al, Mn, Fe, Ni, Cu, and Zn) of Halacsya sendtneri (Boraginaceae; strict serpentine endemic), Cheilanthes marantae (Pteridaceac; broad serpentine endemic/strong indicator), and Seseli rigidum (Apiaccac; weak serpentine indicator/indifferent) growing on serpentine and limestone in Serbia. Element bioaccumulation factor was calculated as the ratio of plant tissue clement concentration to soil plant-available element concentration. Tissue concentrations of Ca and Mg for H. sendtneri and S. rigidum indicate that the species selectively uptake and translocatc Ca to leaves, relative to Mg, to maintain adequate tissue Mg:Ca ratio. C. marantae did not exhibit selective Ca uptake or translocation, but did exhibit Mg sequestration in roots. Heavy metal exclusion and sequestration were the primary physiological tolerance mechanisms conveying serpentine tolerance in the three species. S. rigidum exhibited divergence into serpentine tolerant and limestone tolerant ecotypes, presenting a useful model species for further studies of physiological adaptation to chemically extreme soils.