The authors describe the locality of a so far in Poland unknown species Coleanthus subtilis. It was discovered on the Olenica Plateau near Wroc³aw. This grass occurs on a surface of ca. 15 ha, round muddy shores of fishponds. The large stand makes the impression to be at least 50-year old. Together with the grass of our interest there grow also other, not frequent to day, species like Veronica peregrina, Myosurus minimus and Limosella aquatica. The traditional management of fishponds makes the basis of maintenance of all the species and the whole community. The constant filling with water of the reservoirs and application of fertilisers threatens the existence of the whole rare and interesting ecosystem.

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Anatomical investigations of the stem in seven Zea mays L. Inbred lines were performed on specimens bred in the Experimental Institute of Breeding and Plant Acclimatization in Smolice. Two of the lines (bm1 and bm2) including the gene brown midrib were characterized by a higher digestability. The remaining five lines (S215, S335, 5336, S336A and S339) were selective inbred lines used as components in hybrid breeding at the Institute in Smolice. The investigated lines were compared in respect to 50 anatomical traits of the stem. The comparisons were performed by means of the Wrocław dendrite method. The lines formed three distinct groups according to the degree of similarity. The first group consisted of two lines with the gene brown midrib (bm1 and bm2), the second of four lines (5215, S336, S336A and S339), and the third of line S335. The inclusion of both the lines with gene bm into one group was based on similarity regarding the set of traits of parenchyma, particularly of the peripheral part of the stem, as well as metaxylem and metaphloem traits. However, these lines differed considerably in respect to epidermis traits. It was peculiar that the stomata of the Amaryllis type occurred in one of the lines (S339). Each line made a specific mosaic of traits. The sets of traits characterizing the particular lines were specific in such a degree that they could be used, like a fingerprint, for their identification

The subject of the study was a sectorial chimera of dihaploid winter rapeseed, obtained with the help of gamma ray treatment (30 Gy) during shoot cloning in vitro. One sector of the plant was infected by Erisiphe cruciferarum Opiz ex. L. Junell and the other one was resistant. The anatomical structure of a leaf, divided into the two sectors along the midrib, was studied. The infected part of the leaf blade was thinner and built of a smaller number of palisade and spongy mesophyll cell layers. The size of cells in this sector, both in the epidermis and in the mesophyll, as well as the size of nuclei, chloroplasts and intercellular spaces were bigger than those in the resistant portion. On the other hand, the stomata in the infected segment were smaller but their number was higher than that in the healthy part. The study made it possible to analyse the relation between the anatomical structure of the host plant and the pathogen

The level of spontaneous chromosome aberrations and other phenomena concomitant with mitoses in the meristematic cells of <i>Allium cepa</i> L. adventitious roots grown in water, depends to a large extent on the intensity of bacteria multiplication. From the water culture two strains of bacteria, which were most numerous, were isolated - <i>Agrobacterium</i> and <i>Flavobacterium</i>. A supernatant from bacteria grown on Davis medium induced chromosome sticking together, c-mitoses and the formation of polyploid nuclei in the roots of onion.