The system of concepts, used for the estimation of plants rarity is analyzed and the basic categories of rareness are distinguished: true, diffuse, peripheral and temporal. Lack  of scientific information on ecological and coenotic connections of rare plants is shown and the necessity of complex estimation of rare plant population systems is justified.

Halophytic plant communities of the Russia coast of the Sea of Azov are described using the Braun-Blanquet approach for the first time. Three variants of the ass. Salicornietum prostratae, new subass. Salicornio perennantis-Suaedetum salsae (class Thero-Salicornietea) and ass. Salicornio prostratae-Halocnemetum strobilaceae (class Salicornietea fruticosae) are established. The name of ass. Salicornio-Halocnemetum Korzhenevsky et Kljukin in Korzhenevsky 2000 is corrected in accordance with the rules of the International Code of Phytosociological Nomenclature.

Development and morphogenesis of relictual endemic of Crimean Mountains Silene jailensis (Caryophyllaceae) are studied on the early stages of onthogenesis. The juvenile and immature stages of onthogenesistake one season. In virginal stage, perennial one-axial woody shoot is formed with vegetative apex that functions together with lateral shoots both in lower and terminal parts of the plant. This shoot structure is repeated in the main axle system with branching and forming lateral skeleton shoots.

Drought-resistance of persimmon species and cultivars in the Ukrainian Forest-Steppe is studied. Morphological features of stomatal apparatus of leaves in relation to drought resistance are determined.

Bryoflora in the Ukrainian Forest-Steppe is described. Features of taxonomic and ecological-coenotic structure, types of morphs in connection with main environmental factors (such as light, water supply, substrate, pH) are determined with dividing mosses to ecological-coenotic groups.

In the article, the prognosis of the practical use of Allium L. species in the North Prychernomor'ya is done on the basis of adaptation abilities in relation to basic limiting ecological factors together with phytochemical, food and ornamental importance. Recommendations onto growing of Allium taken from natural flora are offered.

Eight spontaneous habitats of Aronia melanocarpa is found in Western Ukraine. The ecological-phytocoenotic preferences of the species are analysed. An age stages identification key for A. melanocarpa is elaborated. The absolute number of individuals, density and age structure of two coenopopulations is studied. The degree of naturalizing, strategy, as well as current tendencies and limiting factors of distribution is revealed.

List of lichens and lichenicolous fungi of Lugans’ky natural reserve consists of 160 species, which belong to 71 genera, 30 families and 8 orders of Ascomycota, including 29 species new for reserve. In Stanychno-Lugans’ke branch 70 species, in Stril’tsivs’ka steppe – 28 species, in Proval’s’ka steppe – 126 species and in Trekhizbens’ka steppe – 51 species are revealed. Ecological and substrate features as well as the distribution in branches of the reserve are given for each taxon.

A list of species of Erysiphales fungi on the territory of Botanical Garden of Mechnikov Odessa National University is studied. 47 species belonging to 8 genera of the order Erysiphales is found as parasites  of 152 species, 5 forms and 4 varieties of plants belonging to 118 genera and 37 families. The most species-rich genera are Erysiphe R. Hedw. ex DC. (19 species, 40,4%), Podosphaera Kunze (12 species, 25,5%) and Golovinomyces (U. Braun) Heluta (7 species, 14,9%). This article presents a complete list of powdery mildew fungi.

Rocks are characterized in supralittoral zone of the Crimean coast of the Black and Azov Seas. The article presents data on the species list of Cyanophyta in various supralittoral rocky substrates.

Data about new for micobiota of Ukraine lichenicolous fungus – Clypeococcum hypocenomycis D. Hawksw. is reported on the base of specimens collected in Ukrainian Roztochya (Lviv region, Yavoriv district).

The locations in southern Ukraine, ecology and general distribution of the new for Ukraine lichenicolous fungus Pyrenochaeta xanthoriae Diederich  as parasite on the corticolous Xanthoria speciesare provided.