L'evoluzione della cerchia legnosa in Quercus Pubescens W. Ein Quercus Ilex L. nel clima di Firenze

Summary

The evolution of the wood ring in Quercus pubescens W. and in Quercus Ilex L. in Florence (from June 1946 to June 1947).

The present study deals with the anatomical characters of the wood ring of Q. pubescens and of Q. Ilex. In both the specimens the wood of the stem and of the young branch has been investigated.

In both plants studied the cambial tissue of the stem starts dividing at the end of April, reaching its maximum activity from May to June.

On the contrary the cambium of the branch differentiates in Q. pubescens a month earlier (18 March-18 April) than in Q. Ilex (18 April-18 May). While in the branch of Q. Ilex a false ring can be seen corresponding to the autumn months, nothing of the kind is found in the branch of Q. pubescens; though it presents a false ring in the stem.

It is difficult to date clearly the period when the cambium stops its activity, but probably it happens at the end of August in the samples of the stem.

The leaf buds of Q. pubescens and of Q. Ilex open during April-May and the young branch is completely developed at the end of June. In both oaks some buds open in autumn, but the small branches are prevented to develop because of the cold.

No comparison can be made between the opening of the buds and the beginning of the cambial activity in the stem and in the branch.

Considering the evolution of these woods and their relationship to climatic factors, we can see that the cambial activity starts during a period of remarkable rainfall and of regular increase of temperature, and stops almost completely at the end of July, when temperature and dryness reach their highest values.

The autumn rainfall would favour again a cambial activity, but the values of the temperature, regularly decreasing, do not allow it.     

Residui di vegetazione spontanea in Roma

Summary

The A. describes a large remainder of natural vegetation at the periphery of Rome on the «Monti Parioli». Mainly it is Quercus Ilex macchia — evergreen wood, which becomes on the septentrional declivities Quercus Ilex — Quercus lanuguinosa mixed wood; here among the shrubs some not typical mediterranean elements are contained.     

Buxus Balearica Willd., Elemento Mediterraneo-Occidentale della Sardegna

Summary

The occurance of Buxus balearica Willd. in Sardinia, already reported by Gennari (1864), and its indigenous state are confirmed by the present study. Its station and geographic distribution as well as the biocenosis in which this species takes part (Barbusi near Sulcis in S. Sardinia) are considered.

The study of the Barbusi station, in comparison with others hitherto known, brings a general confirmation to Chiarugi's view concerning the mountainous origin of the mediterranea elements. Besides, it emphasizes the differences between the stations of B. balearica, an element of the mediterranea “macchia”, and those of B. sempervirens, an undergrowth element of mesophilous formations (deciduous woods), which only rarely belonges to more termophilous bioceneses.

The author notes that both species belong to the same stage of Q. Ilex and that the altitude range in which the Q. Ilex stage is comprised is very wide in the different mediterranean regions. In addition, the author emphasizes that Buxus sempervirens occurs in Corsica and Atlas up to the upper limit of Quercetum Ilicis, together with species belonging to higher stages, whilst Buxus balearica belongs to the lower limit of Quercetum Ilicis in the underzone “Olea-Ceratonia”. The altimetric separation of these species is, therefore, obvious.

Due to the compenetration of floras of mountainous origin during the phases of the Ice-period, the knowledge of the segregation epoch of these species from each other is made impossible.

Buxus balearica occupies actually as eocene substratum and, therefore, shows edaphic exigences for soils of a certain age: a condition not occurring for Buxus sempervirens.

Both Buxus species, together with other horeal-tertiary ones (all constituting actually, in the mediterranea countries, a special relict flora) belong to the Lauretum, in a historic sense (Chiarugi).     

Evoluzione Del Metabolismo Ossidativo Dei Semi di Ricino Durante la Maturazione

Abstract

Changes of respiratory metabolism in developing castor bean seeds. — The respiratory metabolism and the effect of the removal of the teguments on gas exchanges in castor bean seeds at various stages of development has been investigated. Maximal values of oxygen uptake rate were found in the period of fat accumulation. From this period on, oxidative activity steadly decreased to become, in the mature seeds, almost undetectable.

In all stages of maturation, the removal of the teguments induced a decrease of the respiratory rate of the seeds. This finding indicated that the respiratory rate of the internal tissues is not directly limited by a scarce availability of oxygen caused by a low permeability of the teguments to gases.

The value of the respiratory quotient (R.Q.) was found close to 1 in the first stages, during the growing of the endosperm while in the following period of fat accumulation it rised to 1.6, and falled again, just before the abscission of the seed, to 0.7. This fall of the R.Q. suggests that the oxidative activity of these seeds in the last stages of maturation is supported either by the oxidation of substrates more reduced than carbohydrates (probabily fats), or, partially, by the conversion of fats to sugars.     

Ricerche Sull'ultrastruttura dei Tubi Cribrosi di Piccioli di Foglie di Edera

Abstract

The ultrastructure of sieve tubes in leaf petioles of HEDERA HELIX. — The structural organization of the sieve elements in Hedera leaf petiole at the beginning of the second year of life has been studied. At this stage of life the sieve tubes are completely developed, but still in full activity.

Their plasmatic structures, though altered, show that they are still alive. The cytoplasm forms a parietal layer; mitochondria, endoplasmic reticulum and plastids are present although very peculiar in aspect. The cytoplasm is bounded externally by a plasmalemma; on the contrary no tonoplast is detectable.

The data reported in this paper are favourable to the idea of an active partecipation of the sieve tubes in the translocation of organic solutes, in agreement with the findings concerning the oat coleoptile.     

Fenomeni di Inattivazione e di Riattivazione Enzimatica in Endospermi di semi di Ricino

Abstract

Inactivation and riactivation of enzymes in endosperms of castor bean seeds. — On the basis of previous results, the possibility has been investigated of the reversible interconversion of active and inactive form of enzymes in castor bean seeds, during their development.

The results described here indicate that:

1. the activity of some glycolytic enzymes increases greatly (81% and 400% increase of, respectively, Gl-6-P-dehydrogenase and aldolase) upon incubation of dry seeds for few hours at 4 °C.

2. The decrease of enzyme activity upon dehydration of seeds and the increase during the subsequent imbibition can be shown reproducibly.

3. This same observation is made for oxygen uptake.

These results are interpreted to indicate the reversible inactivation of enzymes caused by dehydration of seeds.     

Formazione di pistilli accessori in “Actaea Spicata“ L.

Summary

One of the most characteristic species of the present Mediterranean vegetation, the holm-oak, still presents in the Appennines, after the alternate glacial periods, relict stations, separated and disjointed, strictly bound to the rocky places.

The Author takes the examination of the altimetrical limits of the holm-oak in Garfagnana (Tuscany), in the valleys of Turrite Secca and Fegana, as a starting point to take into consideration the value and the floristic-oecological aspects of these rocky relicts.

After a climatic and geomorphologic classification of the examined places, the distribution of the holm-oak in the aforesaid valleys is minutely described.

The historical examination shows a derivation of the present plant-communities, rocky and relict, from the dispersion of a presumable anathermic mountain forest, referable to the period of the Quercetum mixtum, rather than to the ancient tertiary, thermophilous and orophilous, Mediterranean forest.

The permanence of the holm-oak in the submontane and mountain stations is strictly bound to their peculiar oecology and its specific temperament. The rocky stations, at least those examined in Garfagnana, are remarkably arid and thermically continental, especially those exposed to the south and south-west. Their aridity, however, helps to lessen the dangers of the frost. The holm-oak can live there in virtue of its tolerance and biological plasticity. To the south it reaches the most elevated heights owing to the protection from cold winds and owing to its greater thermic availability.

A peculiar attention is given to the dynamics, in time and space, of the floral-physiognomical groups: dynamics which has its impulse in the unceasing instability of the rocky micro-places.

Some botanic observation, made in different floral districts, in different conditions of positions, altitude and nature of the substratum, aim at representing the floral aspects of the examined Quercus Ilex-stations.

The flora is constituted with entities fit (preadapted) for the rocky places and with species supplied with remarkable qualities of adaptation. Through the comparisons of the biological spectra, it appears the great fitness of the Chamephytes to the harsh rocky places.

Among the few Mediterranean species able to follow the holm-oak in the rocky localization it is worth mentioning, above all, the Juniperus phoenicea L., species typically of the littoral, never noticed in Tuscany at such elevated heights as those which have been noticed, as it appears in this work, in the Apuane Alps (till 1200 metres).     

Analisi polliniche di fanghi di acquitrini della Pania di Corfino,nell'Appennino Lucchese

Abstract

Pollen analysis of the sediments of a bog on the slopes of Panià di Corfino (Apennines, near Lucca). Fossil pollens in the sediments of a bog situated on the slopes of Pania di Corfino (Lucca) have been studied. The site studied lies on oligocenic rocks and is surrounded by beeches.

From a depth of 120 cm up to 50 cm the prevailing pollens belong to species typical of beech and silver-fir woods. Layers from 50 to 25 cm contain mostly pollen of herbaceous plants and of Ericales shrubs, especially belonging to the genus Vaccinium. The upper layers (25 to 5 cm) show a prevalence of Pinus mugo pollen. These data suggest that, after a long period during which climatic conditions resembled those of the present, a shift to a colder climate lowered the upper limit of the beechwoods.     

Tecniche di Coltura di Semi di Grano Sottoposti ad Operazioni di Trapianto Embrionale

Abstract

Cultural techniques for wheat seeds submitted to embryo transplantation. — The author, on the basis of his experience coming from the work carried out on the embryo transplantation for several years, takes in consideration some aspects, at technical level, regarding the best way to cultivate wheat seeds submitted to embryo transplantation operations.

In particular, the author refers on the possibility to sow the transplants just made (while the traditional method foresees the drying of transplants for 48–96 hours under laboratory conditions) and he illustrates the results of the transplant culture in jiffypots, which allow to improve survival of materials intended for the growth in field.     

Variazioni di Metaboliti Nel Seme di Ricino in Fase di Maturazione

Abstract

Changes of glycolytic substrates level during ripening of the castor bean seed. — The changes of the concentration of carbohydrates and of the main glycolytic substrates in the castor bean seed during the ripening phase were investigated. The following results were obtained:

The level of unphosphorylated sugars and of acid hydrolysable polysaccharides remains almost unchanged, with a tendency to a rise during the ripening phase. The slight increase of these compounds, together with the transition of the R. Q. from high to low values, might be interpreted as an indication of a shift of the seed from the a metabolism of fat synthesis to one of conversion of lipids into sugars, such as is observed in the germinating castor bean seeds.

Hexose monophosphate level sharply decreases during the last period of maturation. However, the level of these substrates does not fall so low as to suggest a severe limitation for the pentose-P pathway activity.

Fructose diphosphate, DOAP, GAP, 3 PGA, 2 PGA, PEP and pyruvate levels consistently increase during the ripening process. This indicates that the drop of oxygen uptake observed in this phase cannot be due to a lack of glycolytic substrates. On the other hand, the ratios between some substrates are shifted, during ripening, from values close to the theoretical equilibrium constants to quite different values. This finding, when correlated with the one of the strong decrease of the glycolytic flow, strongly suggests a severe inactivation of the glycolyting enzymes during ripening.

The increase of pyruvate in tissues showing a decreasing respiratory activity indicates a fall of the oxidative capacity of mitochondria. This might be due to a lack of ADP, or other high energy bond acceptor, following a block of synthetic processes. However, no decrease of ADP level, and an increase of the ADP/ATP ratio during ripening is observed, Among the alternative hypothesis: a) lack or excess of oxalacetate; b) increase of concentration of some Krebs cycle inhibitor; c) inactivation of mitochondrial enzymes, the latter is thought most probable, in view of the finding of a sharp decrease of some other enzyme activities during ripening, of the above mentioned interpretation of the shift of the ratios between glycolytic substrates, and of the very low level of mitochondrial activity in preparation from the mature castor bean seed. These results when correlated with those from parallel investigations on the biochemistry of castor bean seed maturation and germination suggest, as a working hypothesis, that the respiratory metabolic inactivation accompanyng seed repening is due to a general block of the metabolism of ribonucleic acid and thus protein synthesis.     

Fissazione di CO2 da Parte di Entomocecidi di Cuscuta Australis

Abstract

Fixation of carbon dioxide by galls of CUSCUTA AUSTRALIS. — The mechanism of the carbon dioxide fixation by Cuscuta is a controversial biochemical topic. Light induced reactions are involved in MacLeod's opinion while others as Ciferri and Poma believe that mainly a dark-fixation occurs.

In this study use is made of the galls, caused by the insect Smicronyx on Cuscuta australis, that appear more green coloured than the normal tissues.

Equal weights of excised galls were kept both in light and in darkness in contact with C¹⁴O₂for different incubation times, and the magnitude of the fixation was compared under these two conditions by measuring radioactivity of both soluble and acid hydrolysed fractions.

After short exposures to the tracer the fixation in light greatly exceeds that in dark (25–19/1) while with more prolonged exposures the ratio sharply decreases (to about 5/1): these figures can be interpreted with the assumption that a strong light-induced fixation superimposes itself to a low but definite dark-fixation activity.

The ratio does not change if radioactivity is measured in the hydrolysed fractions.

These results are of course referred to as being largerly preliminar and requiring further and more extensive studies.     

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 Preliminari Sulla Struttura Submicroscopica dei Granuli di Amido dell'endosperma Maturo di Triticum Durum Desf

Abstract

Preliminary observations on the submicroscopic structure of the endospermic starch granules in TRITICUM DURUM desf. (The electronic transparency of the starch granules). — The starch granules of Triticum durum Desf. kernels have been examined by electron microscopy.

The high degree of transparency of the granules appears to depend upon the regular disposition of the structural units, while their opacity probably is in relation with their orderless arrangement. The opacity of amorphous portions of the layers, of the median fissure and of the black bands seems to be in relation with the amorphous condition of such formations.

The black bands and the bubbles which have been considered respectively as protein layers and as the result of enzymes action, are only artifacts. The bubbles are interpreted as pyrodestrines.     

Cultura in Vitro di Ovuli di Pinus Pinea L.

Abstract

Pinus Pinea ovules cultured in vitro. — The degree of growth and autonomical differentiation of Pinus pinea L. proembryo has been studied by means of controlled cultures in vitro of excised ovules.

Proembryos in vitro undergo involution and initials of their growth points change back into parenchimatoides cells.

Completely differentiated embryos cultivated in vitro behave as if they were not physiologicaly ripe in all their parts. Embryos cultured in august, september and october develop into rocotless seedlings. Only embryos cultured in november have roots able to elongate where germinating, but in a still scarce degree in comparison with hypocotile and cotiledons. Hypocotil root ratio is inverted as regards what happens in nature.

The primary endosperm of Pinus pinea L. cultivated in vitro undergoes surface diffuse proliferation.

A case of polyembriony has been observed.     

Inquadramento fitosociologico delle leccete dei dintorni di Siena

Abstract

A phytosociological study of the Quercus ilex woods in the surroundings of Siena (Italy). – Numerous stands of Quercus ilex woods around Siena have been studied phytosociologically and compared to the better known similar forests of Southern France. As a rule the Siennese Quercus ilex woods (Table 1) can not be considered to belong to the association Quercetum mediterraneo-montanum Br.-Bl. 1936 because of the absence of various significant central European and montane species, nor to Quercetum galloprovinciale because of the presence of too great a number of Quercetalia pubescenti-petraeae and Querco-Fagetea species. Only rarely communities similar to the first mentioned association have been found: i.e. on Mount Cetona at 1.800 feet and in two particularly cool and humid localities at a lower height (Table 2). Taking into account the way these woods have been managed for centuries it can be concluded that they are mixed formations of Quercetum galloprovinciale and an oakwood association belonging to the order Quercetalia pubescenti-petraeae; the exploitation techniques have caused the evergreen oak to become dominant therefore creating conditions favourable to the more thermophilous and shade loving plants characterics of Q. ilex woods and at the same time bringing about a sharp decrease in the number of the light demanding species typical of deciduous oakwoods.     

Parziale purificazione della DPN-chinasi da foglie di pisello

Abstract

PARTIAL PURIFICATION OF DPN-KINASE FROM PEA LEAVES. — The presence of DPN-kinase has been demonstrated in pea leaves. The enzyme has been purified about 100 fold from this material. The possible significance of DPN-kinase and TPN-phosphatase (FORTI et Al., 1962) in the interconversion of pyridine nucleotides is discussed.     

Vegetazione e ambiente delle Marche e relativi problemi di salvaguardia

Abstract

Vegetation and environment in the Marche and related problems of protection. – The « Marche » region is situated in central Italy and corresponds with the natural region east of the Appennine ridge and spreading as far as the coast which is washed by the Adriatic Sea.

As to the climate, we may distinguish a coastal strip with Mesomediterranean climate with dry season, corresponding to the distribution area of Quercus ilex; a hilly strip with Submediterranean climate, corresponding to the distribution area of Quercus pubescens; a mountain strip with temperate axeric climate with sub-dry period, corresponding to the distribution area of Fagus silvatica and finally a high mountain strip with cold axeric climate, corresponding to altitude pastures. The Marche vegetation is shown in the vegetation map of Fabriano sheet (scale 1:50,000) plotted according Ozenda's vegetational series.

The following vegetation series have been plotted: submediterranean series of Quercus ilex; series of thermophilic oak wood with priority of Quercus pubescens or Quercus cerris; series of Ostrya carpinifolia; series of Quercus petraea and series of Fagus silvatica.

As far as the problems to safegard environment are concerned, a plan is given providing for the institution of 4 complete nature reserves, 34 nature reserves, and 9 regional nature parks among which those of Monte Conero, of Monti Sibillini and Monti della Laga.     

Osservazioni Sullo Sviluppo di Lagurus Ovatus L.

Abstract

Effects of boron and molybdenum on the growth of Asparagopsis armata (Rhodophyceae, Bonnemaisoniales) in culture. - The influence of two trace-metals (boron and molybdenum) on the growth of Asparagopsis armata has been studied in culture. This alga is very tolerant of molybdenum at high concentrations, while boron rapidly becomes toxic.     

Alcune Osservazioni Sul Contenuto del Cribro in Giovani Fusti di “Guizotia Abyssinica” Cass

Summary

The area of S. Rossore is part of an old marshy plane, placed on the right side of the mouth of the river Arno and reaching the mouth of the Serchio, which untill some centuries ago flowed indipendently into the Tirrenian and only later has been diversed into the Arno.

On the dunes and downs of S. Rossore a very interesting type of Flora survives; its present physionomy going up to the Quaternary period, could be preserved till today as S. Rossore has been since a long time a private farm and a park of princes, dukes and kings.

The most interesting Flora of S. Rossore is that of the downs, expecially of the oldest ones (pleistocenic) which separated untill historic times, the open sea from the lagoon of Fasana, which penetrated just inside the present walls of Pisa.

For this reason these downs have been studied with a particular care. The floristic research have been based not only in the study of the specimens collected by the author, but also on the material of which the author could dispose. That is: the specimens of the “Herbarium Centrale Italicum” of the Botanical Institute of Florence, the data of the “Prodromo alla Flora toscana” and of the “Supplemento” by Caruel and Baroni. Altogether the taxa listed up to the present date are more than 700.

The identification of the species has been critically made, adopting the rules of the “International Code of Botanical Nomenclature”. When those rules could not be follewed an explanation has been given.

The facies of the vegetation of S. Rossore are the following: The seashores, the dune tops, the wet downs, partially flooded during the winter, and the permanent marshes.

The facies of the meso-igrophilous woodlands, growing expecially in the most encient downs, has been particularly investigated. In these stations grows a mixed wood of Quercus pedunculata, with Fraxinus oxycarpa, Fraxinus Ornus, Alnus glutinosa, etc., with many boreal-montane plants and Sphagna colonies, particularly at the edge of the partially flooded areas. In these Sphagna colonies are located some of the most exigent atlantic species (Hypericum elodes, Hibiscus palustris, etc.).

These mesophilous-igrophilous woodlands represent a relict of the vegetation pushed planewards to sea level by the glacial climate, and to its ingression is due the scarse importance that presently has here the mesophilous macchia of Quercus Ilex, as is shown by the biological spectrum of the flora of S. Rossore, (P 11, Ch 3, H 33, Cr 20, Th 22) indicating a rather scarse mediterranean character, in comparison with that of M. Argentario.

The flora of S. Rossore has a rather low degree of community (70%) with that of the “Paludi Pontine” which are only a short tract southawrd (2°1/2) and which stood the same geological events. On the other side, the lower degree of community between the Floras of S. Rossore and the Pine Forest of Ravenna (60%) which are located at the same latitude, shows the importance of the Appennines placed as a barreer between the floras of Central Italy.

In this paper has been focussed the importance that the coastal marshes can have had for the preservation of an old tertiary flora during the quaternary period. This flora in fact could be able to move, during the Quaternary, from the marches to the impending hills and viceversa, according to the different glacial phases (a tipical example is Periploca graeca).

It has been particularly pointed out the importance of the woodlands of the plane and the coastal marshes in preserving the colonies of montane or boreal-meso-philous-igrophilous species during the interglacial periods, (for ex. Narcissus poëticus, Leucojum aestivum, Menyanthes trifoliata, etc.) This phenomenon is particularly important in the marshes, situated in the lower course of the river Arno, penetrating far into the Peninsula, where they are dominated by the peacks of the Appennines and of the Apuane Alps.

From this research it is possible to argue that some atlantic species (mediter-ranean-atlantic as Erodium maritimum and Anagallis tenella and eu-atlantic as Hypericum elodes) could have spread towards the mediterranean basin along the coastal platforms, which gradually emerged above sem level in consequance of the glacial eustatism.

This migration was possible during the ascending phases of the glaciacions, when the climate was markedly of an oceanic type.

This study has been made with the aim of emphasising the opportunity of the establishment of a “National Park” in S. Rossore, to preserve his relict formation so important to testify the history of the quaternary vegetation of the mediterranean coasts, and particularly the anteclimax of the higrophilous downs, represented by the coastal “Selve”.     

Osservazioni Sull'embriologia di Nerine Rosea e di Amaryllis Belladonna (Amaryllidaceae)

Summary

The embryosac development in Nerine rosea Herb. has been found to occur according to the Normal type and indications of an identical development were found for Nerine curvifolia Herb., contrary to the observations of Schlimbach (1924), who reported a Lilium type for this species. Embryosacs of the Normal type also occur in Amaryllis Belladonna, to which a tetrasporic development had been erroneously ascribed by Schlimbach (1924). In Nerine rosea Herb. the formation of the microspores is of the «successive» type; the aploid cromosome number is n=12, in accordance with the describtions of Heitz.