Drg pierdere în greutate brickell, Transcript

drg pierdere în greutate brickell

Several succulent halophytes, with articulated segments have been anatomically investigated: Sarcocornia fruticosa L. Scott, Arthrocnemum macrostachyum Moric. These species have been collected from Spain, in The nature of articulated segments is still disputed from anatomical point of view, a caulinar or foliar origin being suggested during time.

These structures, as well the succulence are discussed as adaptations of halophytes to environmental conditions.

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Key words: halophytes, anatomy, ecology. În lucrarea de faŃă, am supus investigaŃiei anatomice următoarele specii de halofite suculente, cu segmente articulate, din familia Chenopodiaceae: Sarcocornia fruticosa L. Natura segmentelor articulate este încă disputată din punct de vedere anatomic, ridicându-se problema dacă acestea au origine caulinară sau foliară.

drg pierdere în greutate brickell

Aceste structuri, precum şi prezenŃa suculenŃei, au fost interpretate în sensul adaptărilor halofitelor la condiŃiile complexe de mediu.

Cuvinte cheie: halofite, anatomie, ecologie. In the present paper, we continue the anatomical and ecological research In the Mediterranean region, the drg pierdere în greutate brickell communities represent two categories — those that belong to the maritime salt marshes and those that belong to the salt deserts Chapman, Moreover, as already stated, Mediterranean salt marshes provide special ecological conditions, controlling the spatial distribution of vegetation; this is related to the predominance of several environmental factors and to adaptive set of halophytes Grigore, Toma, Boşcaiu, These have been collected in July offrom a coastal salt marsh from Alicante Spania.

Anatomical investigations were conducted following the method standardized by our group poate lipsa somnului cauza pierderii în greutate Faculty of Biology, Iasi for an extended description of this method, see: Grigore, Toma and Boşcaiu, In Arthrocnemum macrostachyum, in the external cortex of unarticulated stem long or very long brachysclereids are dispersed; these are perpendicular on the epidermis, simple or branched especially at the endswith a thick and lignified wall.

At the limit between the external cortex and the middle one there are located very small vascular bundles, with spiral xylem vessels disposed on a circle.

There follows a special type of cork area Fig. The phelloderm forms a thick area with cells disposed in radial rows having the tangential walls moderately thickened.

drg pierdere în greutate brickell

The stele comprises rings of vascular bundles Figs. The phloem appears like cellulosic isles surrounded by sclerenchyma and the xylem of the conducting vessels.

On the internal face of the first ring, that is, close to the medulla, there are six vascular bundles Fig. In the cortex of articulated succulent segment, there are many stereides Fig. This author considers the stereides and 20 tracheoidioblasts see below as homologous structures.

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ManginMonteil and Mateu Andrés also evidenced them in A. It is interesting that Chermezon did not explicitly mentioned stereides in A.

The stele consists of five lignified rings, with phloem isles; in the lignified part of each ring, vessels towards outside and sclerenchyma fibres towards inside are noticed Fig. When analysing more thoroughly, they seem to be vascular bundles surrounded by sclerenchymatic fibres with extremely thick and intensely lignified wall.

In the central part, four xylem and phloem bundles can be found Fig. The stele of unarticulated stem is very thick, resulting mainly from the activity of the supernumerary cambia. In the central area, internal vascular bundles, with little phloem sieved tubes and companion cells and a little more xylem lignified parenchyma cells and vessels can be observed; on the internal face of each bundle there is a cellulosic parenchyma arch, in whose thickness are visible several vessels or remains of primary xylem which have a little thickened and poorly lignified wall Fig.

The central, internal area is thicker, forming an aqueous parenchyma Fig. According to some botanists Chermezon, this internal cortical layer would represent the upper epidermis of leaf fused with the stem. In the thickness of the xylem body, one can distinguish rings of different thickness, with larger vessels in their internal side, all with very much libriform made of fibres with an extremely thick and heavily lignified wall.

The root axis has narrower vessels, scattered irregularly in the libriform mass.

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From the drg pierdere în greutate brickell of this material, one can estimate the number of supernumerary cambia Fig. The stele of unarticulated stem is thick, with a structure more similar to the one of the root, predominant being the sclerified and lignified part.

In fundamental mass represented by a significant quantity of libriform fibres with an extremely thick and lignified wall numerous and very small islands of phloem, and very few vessels which differentiate by the fibrous elements only that they are slightly wider can be observed Fig.

The centre of the stem is occupied by an air-storing cavity of irregular outline. As in the root, the presence of the phloem islands embedded in the compact 22 mass of xylem in which clearly predominates the libriform shows the same activity as of several supernumerary cambia, although initially the structure was a primary one, with vascular bundles around the medulla. Internal zone is thicker, of water-storage parenchyma Fig.

In the thickness of palisade tissue, tracheoidioblasts can be observed Fig. Scattered among these shrubs Salicornia can be found; it is an annual plant, with similar ecological preferences as the other two species.

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All the species are succulent, at the level of articulated segments; succulence is a typical adaptation in halophytes, with role in dilution of concentrated salts and water storage, since these habitats are affected by physiological drought Grigore and Toma, In addition, these adaptations reveal the close affinity for environmental factors, an interrelation built during co-evolution process plantsaline environment.

Activity conducted by M. Chapman V. Cramer 2.

drg pierdere în greutate brickell

Chermezon H. Fraine E. Grigore M.