Osservazioni embriologiche,sistematiche ed ecologiche su Allium parciflorum Viv.

Abstract

Embryological, systematic and ecological observations on Allium parciflorum Viv. The morphological observations and the comparison with some allied species have shown a good taxonomic isolation of Allium parciflorum: this has suggested to ascribe it to a new section.

It has been observed that the female gametophyte develops according to the disporic-type, as in other species of Allium previously studied.

The distributional area in Sardinia has been considerably extended and many ecological data are also given.     

Osservazioni Anatomiche Su Alyssum Leucadeum Guss

Summary

Alyssum leucadeum Guss. is an endemic Apulian chamephyte, growing on rocks; material collected at Santa Maria di Leuca has been studied anatomically and the following observations have been made.

In the basal thick woody stem the sclerenchimatic tissue is well developed, and is divided up, by parenchima, in many bands which are normally disposed in regular concentric rings while in some cases a single band can be separated by the parenchimatic tissue into «islands» forming tangential rows.

A few tubes are to be found in the sclerenchimatic bands but in very small number compared with the tubes observed in the parenchima. At times a sclerenchimatic band can be connected to the next one towards the outside through radial sclerenchimatic strands, making the stem more resistant mechanically.

The parenchimatic bands interposed between the sclerenchimatic ones are composed of parenchima cells rich in starch. Starch consumption proceeds from the inside towards the outside and the outer bands are richer in starch. Inside the parenchima bands are islands of conducting tissue: the tubes being neither numerous nor large, as is to be expected in a xeromorphic plant. The islands of conducting tissue are sometimes surrounded by a sclerenchimatic sheath.

The alternate succession of concentric rings of soft and hard tissue, together with the arrangement of the conducting elements in isolated groups inside the soft tissue, the groups being sometimes surrounded by a mechanical sheath, show that the stem is provided with great plasticity, is able to shape itself according to the space it finds in the rocks, and can undergo deformations, compressions, etc. An even greater plasticity can be obtained if necessary by resolving the sclerenchimatic bands in several smaller islands. Such a structure, apart from the width of tubes lumina, recalls somehow the secondary structure of certain lianas where the succession of soft and hard tissues gives a great plasticity to the stem.

The structure of the root is similar to that of the stem, the parenchimatic bands being thicker in the radial direction and having cells completely packed with starch.

Alyssum leucadeum is therefore a rock plant with a well defined anatomical constitution and particularly adapted to its habitat. It is a xeromorphic plant, with small tubes, rich in sclerenchimatic and reserve stisues, defended against transpiration by a complex covering of hairs, utilising the winter-spring season for its growth, and the summer as its resting period. Such an annual rithm shows the oriental affinities of this species while the presence of endogenous buds and of a thick layer of cork are other characteristics of plants particularly adapted to a rocky habitat.     

Considerazioni ecologiche su alcuni geofunghi e idrofunghi

Abstract

Ecological considerations on some geofungi and hydrofungi. Some ecological aspects of the terrestrial and aquatic mycoflora are preliminarily examined, emphasizing in particular the ecological relations between fungi and environmental factors. The author adds a personal contribution based on his researches on the composition of Ticino river's fungal flora, controlled monthly in and around Pavia in the years 1973 and 1974, and on the quantitative production of aflatoxin B₁ by a toxinogenic strain of Aspergillus flavus in the presence of herbicides.

Yeasts represent the main component of the fungal flora of river waters, with a prevalence of Rhodotorula (R. rubra) in winter, Candida and Geotrichum in summer. In the zones of the river where industrial or urban discharges arrive, the population of yeasts is greater than in the North and South zone of the town. The data about the population of yeasts, chiefly of the genera Rhodotorula, Sporobolomyces and Candida, prove that these fungi are good biological indicators of contamination of a waterway.

As far as aflatoxins are concerned the author points out the stimulating influence of the herbicides Pyrazon (PCA) and Diuron (DMU) on the production of aflatoxin B₁.     

Notizie ecologiche,cariologiche e sistematiche su Nepeta foliosa Moris

Abstract

Some ecological, caryological and systematic data on Nepeta foliosa Moris. – Nepeta foliosa is a rare Sardinian endemic species, which lives at an altitude of 1200 m, on the Oliena calcareous mountains in Central Sardinia. Its somatic chromosome number is 2n = 36. From a taxonomical point of view, N. foliosa appears a well isolated species within the Nepeta section, where recently Turner placed it. It shows affinity with species of the Pycnonepeta Benth. section, and particularly with Nepeta multibracteata Desf. For this reason it is here proposed to transfer N. foliosa into the Pycnonepeta section.     

Osservazioni preliminari al microscopio elettronico a scansione sulle ornamentazioni delle spore di Russula

Abstract

Preliminary observations on spore ornementation of Russula, as seen in the scanning electron microscope. — The spores of 16 species of Russula have been examined in the scanning electron microscope, as a preliminary attempt to see if an accurate examination of the spore surface at the ultrastructural level could reveal details of ornamentation which might be useful for the classification of the many species of this genus. The examination, carried out both on fixed and unfixed specimens, has demonstrated that the spore shape is always round or slightly elliptic, and that the obnormal forms as previously described are probably artifacts. Five main types of ornamentation have been described: single wart-like and single finger-like Protrusion, wart- or finger-like protrusions interconnected by thin ridges, and thick, short « papillae » together with large ridges that run along large tracts of the spore circumference. The type of ornamentation was a constant character in each species.     

Osservazioni ultrastrutturali su particolari organelli polimembranosi in Euglena gracilis

Abstract

Ultrastructural observations on polymembranous organelles in Euglena gracilis. Polymembranous organelles, similar to hypertrophied mitochondria, seen in the cytoplasm of bleached or photosynthetic Euglena gracilis cells are presented.     

Osservazioni Sull'effetto Inibente di Elevate Pressioni Osmotiche su Diversi Tipi di Crescita

Abstract

On the inhibition of seeds germination and of growth by cell enlargement by the osmotic pressure of the medium. — The mechanism of inhibition by osmotic pressure (O.P.) of the medium on growth and respiration of germinating wheat, castor bean and lettuce sèeds and of etiolated pea internode segments was investigated.

The following results were obtained:

1 - External osmotic pressure (up to 0.3 M) of various substances such as mannitol, urea, glucose, NaCl, was shown to inhibit the germination and growth of lettuce, wheat and castor bean seeds.

2 - a) A remarkable decrease of the development of respiration during the first 48 h of germination was demonstrated in embryos of wheat seeds germinated and maintained in mannitol solutions at concentration from 0,2 to 0,3 M.

b) A slight but reproducible inhibition of óxygen uptake by O.P. was also observed in embryos isolated from wheat seeds germinated in water for 24 and 34 h and transported respectively in water or into 0,2 M mannitol solutions.

This is interpreted as indicating that high external O.P. inhibits both the respiratory metabolism and the development with time of enzyme systems supporting respiration.

3 - Mannitol solutions (0,2–0,3 M) inhibited completely growth by cell enlargement in pea internode sections, while they did not at all affect oxygen uptake and protein synthesis ( ¹⁴ C - leucine incorporation). The stimulatory effect of auxin on pea elongation was almost completely suppressed by mannitol, whereas the hormone stimulation of respiration remained unchanged.

These data are interpreted as indicating that in tissues, presenting an advanced differentiation, high external O.P. inhibits growth by a direct physico-chemical mechanism; while the inhibitory effect in embrional tissues seems to comprehend, besides this direct effect, a complicated metabolic component, apparently influencing protein synthesis.     

Osservazioni su un caso particolare di cicatrizzazione di un olivo danneggiato dalle minime termiche del febbraio 1956

Abstract

OBSERVATIONS ON A SPECIAL CASE OF WOUND HEALING IN AN OLIVE TREE DAMAGED BY LOW TEMPERATURE IN FEBRUARY 1956. — The authors have observed an unusual form of woung healing in an olive tree damaged by low temperature in 1956, and have studied its morphological and anatomical details.

Attention is drawn to the notable ability of olives to recover from low temperature damage, especially through the activity of the subsidiary trunks « corde » characteristic of the olive tree.     

Schede palinologiche diArtemisia vulgaris L.,Artemisia verlotorum Lamotte;Artemisia annua L., su campioni freschi e acetolizzati

Riassunto Sono state allestite le schede palinologiche diArtemisia vulgaris L.,Artemisia verlotorum Lamotte eArtemisia annua L. su polline fresco e acetolizzato. Le tre specie hanno interesse aerobiologico e allergologico. Vengono anche riportati dati sulla loro distribuzione in Italia, con particolare riferimento adArtemisia annua.      

Osservazioni sulla microflora fungina di ceppaie di abete bianco

Abstract

Mycoflora of Silver fir (Abies alba Mill.) stumps. - This work is a first contribution to the knowledge of the mycoflora colonizing Silver fir (Abies alba Mill.) stumps in Italy.

Autochthonous fungal species were isolated from the wood of A. alba stumps from three different sites in the Tuscan Apennines.

Frequency values for the isolated species and taxonomic groups were calculated.

Deuteromycetes (57–82.5%) occurred more frequently than basidiomycetes (5–36%), phycomycetes (0.7–11.6%) and ascomycetes (0–1%). The most common genera were found to be: Aleurodiscus, Penicillium, Phellinus, Phialophora, Scytalidium, Sistotrema and Trichoderma.

An effective method of isolation from wood is also described.     

Osservazioni sulla biologica dellaProspaltella perniciosi Tow. nella valle Padana

Summary Investigations have been carried out in the Po' Valley (Italy) during 1964 to establish the number of generations of the San José scale and its parasiteProspaltella perniciosi Tow. It was found that the San José scale has three generations per year, while its parasite has six. The percent of parasitism attained in one year after parasite release was 60.Prospaltella hibernates as an egg in the first larval instar of its host.      

Osservazioni Anatomiche Su Una Forma Teratologica Di Tulipa Orientalis Levier

Abstract

Anatomical observations upon a teratological form of TULIPA ORIENTALIS Levier. — The author illustrates a singular case of abnormal concomimitances in Tulipa orientalis Levier, which hears six flowers on the same scape: three of these flowers are disposed in a terminal « bouquet » and three at different heights in the scape.

Almost all the pistils of these flowers were tetracarpellate; one of them being greatly hypertrophic in respect of the others, and completely devoided of ovules.

Very interesting for its rarity and here observed for the first time for the Tulipa genus, is the presence of a very small and almost perfect supernumerary tetracarpellate pistil, joining the normal pistil of one of the terminal flowers, and the origine of which can't be ascribed to a simple scission, but only to an evident case of multiplication as the two pistils appear distinctely independent.     

Structural and histochemical changes during seed development of Brassica macrocarpa Guss.

During seed formation of Brassica macrocarpa the development of the embryo precedes that of the integuments; structural changes and histochemical changes are associated. Esterases, acid phosphatases, phenols and starch follow a sigmoid pattern, increasing during embryogenesis and decreasing during seed maturation. In the mature seed, esterase activity is localized in the embryo and in the cells of the mucilaginous, aleuronic and hyaline layers. Acid phosphatases are present in the mucilaginous cells, mainly in the column, the cell walls delimiting intercellular spaces of the cortical cylinder and the adhesion areas of the cotyledons. Phenols are scanty in the root apex, mucilaginous cells and the palisade layer, and abundant in the pigmented layer. Starch is absent in ripe seeds which have lipid and protein reserves. The major classes of storage proteins have molecular weights of 21, 22, 27 and 30 KD and accumulate in the late stages prior to complete drying. Esterases and acid phosphatases in mucilaginous cells of the seed integument suggest that these enzymes are involved in hydrolytic processes occurring prior to germination and that mucilages have a metabolic function in seed-soil interactions.     

Osservazioni Su Vari Casi di Fasciazione in Vitisk Vinifera L.

Summary

The Author describes some cases of bandage of vine branchs and bunchs of grapes in a cultivated vine in the form of a bower. About various cases of natural bandage, he retains that these phenomenons cannot well habe a determined origin but various causes possibly have on influence over the manifestation of these abnormal processes about the susceptibility of some subyects towards forms of deviating development. The vine branch's bandage is for the delineated cases, in correlation to the simultaneous development of two vegetative cones from someone bud, with the following conyoined development with two increased together vine branchs, while the bandage of bunchs of grapes springs from the union of floral secondary aces and from very great activity of the productive organs.