When growing in the field, plants are exposed to the effect of heavy metals as soon as the seed comes into contact with the soil solution. Therefore, we found important to study the effect of Cd and Ni on maize exposed to these heavy metals since sowing. The aim of this work was to examine which anatomical changes are induced by continuous intoxication of young maize root system with 0.1 mM Cd and Ni, thus modifying its growth and capacity for water and nutrient uptake. Concomitantly, the effect on concentration and distribution of Cd, Ni and some essential ions (Ca, Mg, Zn, Fe, Cu and Mn) was studied.Additional key words: continuous heavy metal intoxication, mineral nutrition, Zea mays.

Krstic L., Malencic Dj. and Anackov G. 2006. Structural investigations of trichomes and the essential oil composition of Salvia verticillata. Bot. Helv. 116: 159 -168.The morphology of glandular and non-glandular trichomes and the essential oil composition of Lamiaceae play an important role in the ecology of these species as well as for their industrial use; they may also serve as taxonomic criteria. We studied the trichome anatomy and essential oil composition of three wild-growing populations of Salvia verticillata in Serbia to determine how strongly these traits vary among and within Salvia species, and to evaluate their potential taxonomic or economic significance. Microscopic investigations of leaf and calyx indumentum revealed that S. verticillata has the same types of peltate and capitate trichomes as other Salvia species. In combination, however, the trichome characteristics of S. verticillata differed from previously examined Salvia species and might therefore help in species identification. The density of glandular trichomes differed among the three populations and was lowest in a dry steppe habitat, but trichome density also varied substantially among individual leaves within each population. The essential oil content (determined gravimetrically in n-hexane) ranged from 0.40% to 0.42% of dry mass. In total, 39 different oil components were identified using GC-MS. Oil composition varied considerably among the three populations. Only three of the 39 compounds were well represented (> 0.1% of oil) in all three populations: The main component was germacrene D in two populations (48.0% and 24.6% of oil, respectively) but (E)-caryophyllene (10.2%) in the third. Low oil content and high variability in oil composition may restrict the industrial use of wild-growing S. verticillata plants.

The microscopic analysis of leaXet, petiole, stem and peduncle of 26 populations of 17 Trifolium species was carried out in order to examine their structural characteristics related to digestibility, to compare them between the populations of forage species and their wild relatives and to evaluate, from histological aspect, the potential of wild-growing species to be used as forages. Forage species had low proportion of the tissues composed of thick-walled cells and high proportion of the tissues composed of thin-walled cells in all examined plant parts. The reduction of the proportion of ligniWed xylem, sclerenchyma and sclerenchymatous interfascicular parenchyma, were suggested as basic selection criteria in breeding Trifolium species for improved digestibility. T. angulatum, T. medium and T. pannonicum proved to be very similar to the forage species in their histological composition, proportion of thick-walled and thin-walled cells and type of variation of the examined parameters. We believe that these species have some potential for use as forages in their own right, but aditional biochemical, physiological and morphological investigations should be conducted.

The Lathyrus species are wild relatives of cultivated peas. Results of morphological, anatomical and physiological analyses of Lathyrus latifolius L. are presented in this paper. Certain measured parameters and observed morphological characteristics are not in agreement with available literature data, whereas no reference to the winged stem width, length of inflorescence pedicle, calyx length and leaflet index can be found. Two forms, f rotundifolium RCHB and f. latifolius BECK have been determined. Leaflets are amphystomatic, with anisocytic stomata present in almost equal number on both epidermises, dorsoventral, with one-layered palisade and many-layered spongy tissue. Stem in transverse section is rotund to oval with two long lateral wing-like expansions and cortical bundles. Mineral element analysis shows that the highest N, P and K concentrations were obtained with the flower while Ca and Na with the leaf. Leaf pigment content was higher than stem content while net photosynthesis rate was twice as high as respiration rate

Iva xanthifolia is a North American weed species, which was introduced and naturalized in Europe. Anatomical and micromorphological characteristics of this species were investigated, in order to get better knowledge of its biology, which could help in development of strategies for prevention of its spreading. Detailed descriptions of lamina, petiole, stem and inflorescence axis anatomical structures were given, together with micromorphological characteristics of epidermis and indumentum of lamina, petiole, stem, inflorescence axis, involucre and fruit. All vegetative organs had mesomorphic structure, with some xeromorphic adaptations. Mechanical tissue was well developed, which gave those plants additional strength and resistance. Trichomes were the most numerous on lamina and in the region of inflorescence, while rare on petiole and stem epidermis and their distribution varied according to plant organ

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