Romanian Journal of Biology - Plant Biology
Volume 53, No. 1, 2008
1. Cyto-histological aspects in the modified leaf of Dionaea muscipula Ellis
IRINA STĂNESCU, C. TOMA, IRINA GOSTIN
In the present work, the authors evidence some of the particularities observed in the modified leaf of Dionaea muscipula; the upper epidermis presents a lot of multicellular digestive glands, consisting in a basal cell, located among those of the epidermis, a stalk-cell and a hemispheric multicellular massive. The ultrastructure of the glandular cells confirm that the proteolytic enzymes secretion take place not in the proper glandular cells, but in the subjacent ones.
2. Ultrastructural assessment of the tolerance of Nicotiana tabacum L. (cv. Xanthi) regenerants cells to succesive stress induced by PEG (6000)
The present study reveals the ultrastructural changes in cells of tobacco regenerants incubated for 45 days on the regeneration medium supplemented with 5% PEG (6000) and subcultivated during 90 days on regeneration medium supplemented with PEG (6000), in two different concentrations: 5% and 10%. The observed ultrastructural aspects confirmed that the successive treatments with PEG induced the decrease of the tolerance level of cells against the stress caused by drought, leading to the reduction of the morphogenesis potential.
3. Morphometric data about seed coat ornamentation with taxonomic considerations in Jovibarba heuffelii (Schott) A&O Löve (Crassulaceae) populations from Southern Carpathians
V. BARCA, NICULAE MARILENA
The seed coat ornamentation pattern was generally used in the systematics of other Crassulacean genera. Previous work showed a considerable variation of this character within the genus Jovibarba Opiz. In this paper it was investigated by optical and electronical microscopy SEM the seed coat ornamentation constancy among 9 Romanian populations of Jovibarba heuffelii (Schott) A&D Löve to evaluate the infraspecific reliability of this character. Morphometric data and SEM micrographs of a representative seed coat and ornamentation details are presented about the Romanian material, showing homogeneity of seed size, shape and pattern. The seed coat shows a more or less irregular network of crisscrossing longitudinal and transversal broken ridges, without constant cell pattern or any wart-like protuberances but fitting the general characters of Knapp’s "Leitermodel" (10). Although quite homogeneous within the populations examined by us, the Romanian material departs from the "Jovibarba Type" a.3. pattern reported by Knapp, being rather similar to the a.3. "Net structure" he described in Orostachys japonicus, but with sinuous longitudinal ridges exceeding 20 per seed. The dissimilarity with Knapp's "Jovibarba Type" existing in the Romanian populations suggests that the seed coat morphology has a considerable intraspecific variation between distant populations, a fact that could not be neglected when assessing its taxonomic value even at infraspecific level.
4. Ecological anatomy investigations related to some halophyte species from Moldavia
M. N. GRIGORE, C. TOMA
The authors investigated the vegetative organs of three halophyte species, and evidencing some histo-anatomical features (aerenchyma, endodermis, bulliform cells, protective and secretory trichomes), which are discussed in relation to their ecological significance.
5. Chemical constituents of the essential oils of Nepeta nuda L. ssp. nuda (Lamiaceae) from Romania
IOANA MARCELA PĂDURE, D. MIHĂIESCU, LILIANA BĂDULESCU, I. BURZ
The essential oils of Nepeta nuda L. ssp. nuda obtained by hydrodistillation using neo-Clevenger extractor have been analysed and characterized by capillary GC-FT-IR systems. Eucalyptol was the most abundant component of N. nuda oils in different percentages: chemotype Basarabi (34,8%), Frăsinei (44,87%), and Herculane (31,9%). Nepetalactone isomers were found in all ecotypes in various amounts due to ecological conditions, analytical method and plant phenophase.
6. Phytocoenological contributions to the vegetation of Moldavia (Romania)
N. ȘTEFAN, I. SÂRBU, A. OPREA
A new coenotaxon, namely as. Staticeto-Artemisietum santonicae Țopa 1939, subass. asteretosum oleifolii subass. nova is proposed in this paper. This paper features also some comments on the ecology of the halophylous vegetation from the basin of Ciric river. This paper includes a newly proposed coenotaxon, as well as the conservation of the natural vegetation in the investigated region.
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