Ricerche Sulla Vegetazione della val Gesso

Abstract

An interesting discovery in the Maritim Alps flora. ARTEMISIA CAMPHORATA Vill. with galls of DIARTHRONOMYIA KIEFFERI Trotter. Its geographical distribution and phytogeographical analysis. — The Author signals the finding, in the Maritim Alps flora, of some stations of an interesting discovery: Artemisia camphorata Vill. with galls of Diarthronomyia (Rhopalomyia) Kiefferi Trotter, and explains the characteristics of this Cecidomyide, (gall-midge).

He exhibits the results obtained through inquiries (investigations) directed to define the geographical area of Diarthronomyia Kiefferi, in reference to that of its host plant, of which the zoocecidium is exclusive.

The author makes also a map of the area and analyses the phytogeographical characte ristics and the mediterranean physiognomy of the new found stations.     

Ricerche Sulla Vegetazione dei Dintorni di Firenze

Summary

It is related on some phytocenoses of the southerly Florence hills, lying on the boundary of the two basal biochores of peninsular vegetation. Although the proximity and the chorographical analogy at the south-westerly ones and at Ceceri Mount, which are included yet in the » Quercetum Ilicis « ambit, these hills are whereas sensible displaced in the » Quercetum pubescentis «. They have microtherme elements of higher planes, but they have in yet the marks of littoral biochore, for instance Smilax aspera, abundantly penetrating in hedges and in a pine-grove but non in coppices of Quercus Cerris.     

Ricerche Sulla Vegetazione dei Dintorni di Firenze

Riassunto

L'A. espone in questo lavoro i risultati di ricerche sistematiche e fitogeografiche sulla vegetazione di Monte Ferrato (presso Prato in Toscana), piccolo gruppo di colline costituite da rocce ofiolitiche (serpentino, eufotide ecc.), Dopo averne elencata la florula, dove riporta anche le diagnosi di alcune forme nuove, l'A. prende in esame la vegetazione dei principali tipi di stazione, che vi ha potuto riconoscere, in base a criteri fisionomici e statistici. Considera poi le caratteristiche morfologiche delle specie pi[ugrave] significative del serpentino, che raggruppa in cinque tipi di speciali morfosi. Sulla base dell'analisi della distribuzione geografica di alcune notevoli entità che si presentano a M. Ferrato in stazione disgiunta rispetto al loro areale, dello studio geografico e sistematico degli endemismi, e in genere poi di tutte le specie pi[ugrave] significative di questa Flora, l'A. ne discute il valore fitogeografico e climatico, rilevando e discutendo la convivenza di specie di diverso valore fitogeografico, in rapporta alle particolari condizioni microstazionali.     

Ricerche Sulla Flora e Vegetazione dei Fontanili Dell'Agro Milanese

Abstract

Nucleic Acids in Ripening of Castor Bean Endosperm. - I. Quantitative and Qualitative Changes of total RNA. — The ripe Castor Bean seed endosperm (Ricinus Communis var. Sanguinea) has a very low level of nucleic acids and particularly of ribosomal RNA. However, they rapidly increase during the germination of the seed (S. Cocucci et al., Acc. Naz. Lincei, 38, 545, 1965).

The behaviour of the nucleic acids, obtained by phenol extraction from Castor Bean seed endosperm at different ripening stages, is the following:

1. From the moment when the developing seed has reached the maximal fresh weight to the moment of its complete ripening, the RNA content decreases from about 700 μg per seed to about 200 μg.

2. During the same period the DNA level (about 13–15 μg per seed) remains nearly costant.

3. Fractionation by sucrose density gradient of the phenol extracted RNA (H. L. Sanger and C. A. Knight, Biochem. Biophys. Reserch Commun., 13, 445, 1963) shows that during the ripening of the seed the high molecular weight RNA decreases much more than the low molecular weight RNA.

4. Radioactive phosphate injected in the seeds is incorporated in the RNA at all the stages. Fractionation by sucrose density giadient shows that the phosphate is essentially incorporated in low molecular weight RNA and there is pratically no labelling of the heavier RNA after quite a long period (2 hr.).

These data suggest that the decrease of the RNA during the ripening of the seed can be due to a fall in the ability to synthesize high molecular RNA.     

Ricerche sulla Vegetazione della Valsesia

Summary

The present work, forming a part of the research on the Valsesian vegetation, is an investigation of the botanical aspects of one of the tributary valleys of the Mastallone torrent, the Sabbiola valley.

The valley has steep flanks cut into compacted crystalline rock; this morphology is very different from other valleys cut through esasily erodible rock, and with gentle slopes, and has marked influence on the vegetation.

At the base of the valley a forest of Alnus incana and Fraxinus Ornus and, ascending, a stand of chestnut trees not very extensive was noted.

Betula pendula was noted as high as 1200 meters (above sea level). Beech trees, more or less heliophilus or acidophilus are extended lo higher elevations, up to 1500 m., and started at about 850–900 m. The hypsophylous conifers were missing and the “cacuminale” vegetation was neither very extensive or typical, because even the highest elevations of this valley are relatively low for this type of vegetation.

The study of the vegetation of this valley upon completion will be incorparated and inte preted together with the results of other research on the Valsesian region.     

Ricerche Sulla Vegetazione Della Valsesia. VII. Notholaena Marantae (L.) Desv. in Valsesia

Abstract

Researches on the vegetation of Valsesia. VII. «Notholaena marantae» (L.) Desv. in the Sesia Valley. — It's hereby described a station of Notholaena marantae (L.) Desv. near «Giavina Rossa» (Valsesia-Piedmont, Italy). This is probably the only place in the whole valley. The fern grows in a kind of ground formed by peridotitic rocks and on a little dry wall supporting the debris. The fern presence in a wooden valley, and under an oceanic climate could be a very interesting subject for hystorical geobotanic researches.     

Ricerche Sulla Morfogenesi Dei Plastidi Clorofilliani

Abstract

Studies on chloroplast morphogenesis. The effect of sucrose feeding and light intensity on the plastids of etiolated plants. — The changes in the fine structure of the plastids of etiolated Bean plants, dipped into water or in various sucrose concentrations, for 24, or more, hours, and exposed to conditions of darkness and weak light, were studied at the electron microscope, and protochlorophyll, chlorophyll a and chlorophyll b contents were determined. When the etiolated plants are dipped into water or sucrose solutions, in the dark, rows of tubules and lamellae, often stacked and resembling small grana, are formed in the plastids. These structural changes of plastids of the plants exposed to conditions of darkness, where no protochlorophyll was converted to chlorophyll a, are quite similar to those described by several Authors for plants exposed to light conditions and thought to coincide with the protochlorophyll-chlorophyll transformation. Thus, the preservation of the « Kristallgitterstruktur » of the vesicular centers, or, instead, their transformation into a lapse cluster of tubules, does not seem to be related with protochlorophyll accumulation in them; indeed, an increase of protochlorophyll contents was observed both with the preservation of the crystalline structure, and with its transformation, and low protochlorophyll contents did not always coincide with the transformation of the vesicular centers. In the plants exposed to weak light (1 ft-c) there is chlorophyll a and b accumulation, and a more pronounced tendency toward stacking of tubules and lamellae. In the plants exposed to weak light, dipped into water or sucrose solutions, at the lowest concentrations, and for the shortest periods, the vesicular centers are transformed into clusters of tubules; but with higher sucrose concentrations, or longer dipping periods, their crystalline structure is preserved, just as if their preservation would depend only by an adeguate nutrients supply.

The arrangement of normal lamellae and the formation of grana connected by intergrana lamellae occur, anyhow, only when the etiolated plants are exposed to « high » light (630 ft-c). But chlorophyll accumulation is possible under « weak » light (and a stacking of tubules and lamellae, resembling small grana, also occurs), when sucrose is supplied. The achievement of the « normal », complete structure of the chloroplast is, therefore, here interpreted in the sense that it represents only the functional aspect of its organization, determined by a light intensity favorable to its photosyntetic activity, which is not directly necessary for the synthesis of the contistuents of the lamellar system (chlorophylls, phospholipids).     

Ricerche Sulla Simbiosi Micorrizica Nelle Epatiche

Riassunto

Dopo aver constatato come i risultati delle ricerche sin qui compiute sulla micorrizia delle Epatiche siano poco soddisfacenti, l'A. riferisee di aver osservato in molte Epatiche tallose una doppia infezione, da parte di um Ficomicete, che viene descritto, e di un Micomicete di tipo rizottonioide; soltanto quest'ultimo è presente nelle Epatiche fogliose. Illustra l'influenza dei principali fattori ambientali sull'infezione ficomicetica e le probabili cause dell'influenza stessa, e prospetta alcune ipotesi sui rapporti fra i membri della simbiosi.     

Ricerche Comparate Sulla Morfologia e Sulla Fisiologia di Larix e di Picea

Abstract

Comparative researches on morphology and physiology of PICEA and LARIX. The chlorophyll content of seeds and seedlings during germinations in darkness. — Very different are the chlorophyll contents of the seeds and the seedlings of Picea excelsa and Larix decidua grown in darkness.

In Picea chlorophyll is abundantly synthetized in cotyledons in the passage from seed to seedling stages. In Larix however this synthesis is very poor. These differences are more evident after the outgrowth of cotyledons from the primary endosperm and its exhaustion.

If seedlings of both species are exposed to 3.000 lux of light intensity for 24 hours, after development in darkness, one can observe much stronger chlorophyll synthesis in Larix cotyledons than icea.

These figures quanti atively express the different light-dipendence of chlorophyll synthesis in these two plants and offer a more adherent interpretation of the different ecological behaviours that are caracteristic of these two plants.     

Ricerche Sulla Istologia del Legno Secondario Delle Gymnospermae

Summary

The anatomy and histology of the secondary wood of Pinus halepensis Mill. has been studied.

The wood of Aleppo Pine does not differ from that of the other Conifers already investigated.

The tracheids shaw a strong dimorphism, with the presence of prevalently conducting elements and strongly mecanic ones.

In both spring and autumn woods the two tipes of elements are to be found, although in different proportions.

The best character to espress this dimorphism seems to be »trachcids length «.

The conducting elements are shorter, while the mecanic ones are longer.     

Ricerche Sulla Flora Infestante Delle Colture in Italia

Abstract

Studies on the Weeds of Cultivated Land in Italy

II. - Weeds of a small Farm (PODERE « CASCINE »), Near Florence     

Ricerche Sulla Flora Infestante Delle Culture in Italia

Summary

Studies on the weeds of cultivated land in italy

I. - bibliographical and methodological introduction

In the 1rst part of this paper the Author outlines the weed problem, discusses the meaning of the term “weed”, agrees with Korsmo (1930) in considering weeds as constituing a biological group characterised by certain adaptments to life.

After a short survey of the chief European and American books on weeds, he gives a more detailed account of the Italian literature which is not, the Author thinks, very rich on this subject.

In the 2nd part the Author discusses several aspects and some methodological questions of the study of weeds.

After dealing briefly with the floristic and quantitative analysis of weed floras, he goes on to outline the problem concerning the origin of the weed species of a given district; these can be considered as belonging to two main groups: local species which were present in that station before the soil was tilled, and exotic species introduced, often unwillingly, by man through his commercial and industrial activities. The line between the two groups is hard to draw, especially in countries of ancient civilization ad extensively cultivated, where in very few places the local flora has been left undisturbed. It is perhaps easier to distinguish the two main groups of species according to their geographic area of distribution and to the type of stations preferred within that area.

The study of weeds dissemination is strictly connected with the one of their origin.

The next main field of study is the ecological one: having shown the main ecological effects of agricultural technique, which also acts as a levelling agent for the vegetation of the earth, the Author agrees with E. P. Evans (1928) in stating that it is not easy “to draw any but very general conclusions” owing to the undeterminate and variable nature of the human biotic factors, which, together with natural ones, control weed growth. A great amount of research has been carried out on ecological problems a swell as sinecological and mainly agricultural ones concerning weeds. Examples are given, with reference to several Authors.

Lastly the Author stresses the importance of the biological study of weeds and describes at length the biological classification employed by Korsmo (1930), who devides weeds in three main groups, namely: “seed”, “stationary”, and “wandering” plants.

The bibliography is meant to give an useful list of references for the student, but is far from being complete, except as far as Italian literature is concerned.     

Rilievi Sulla Vegetazione del Valdarno Superiore (Rignano Sull'Arno)

Riassunto

Si elencano altre 107 specie vascolari da aggiungere alle 569 già pubblicate in un primo Contributo sulla vegetazione dei dintorni di Rignano sull'Arno. In base alla categoria biologica di Raunkiaer assegnata a ciascuna speice, si traggono considerazioni sul carattere della vegetazione stessa. Si riportano quindi alcuni rilievi eseguiti, sempre con sistema di Raunkiaer(consigliato da Negri), specialmente sulle fitocenosi del bacino sedimentario pliocenico di Marnia, che presentano un grande interesse. Si nota l'urto e la compenetrazione di due consorzi eterogenei, l'uno mediterraneo e l'altro montano-continentale, e si pongono in risalto interessanti formazioni atlantiche di brughiera, analoghe a quelle già rilevate da Corti nelle colline a S-W di Firenze. Rispetto alle cenosi di queste colline, ammessa un'antica continuità fitocenotica, presumibile dalle spicate analogie attuali, quelle di Marnia, adiacenti al piano basale di Pratomagno, costituiscono un gradino a carattere un poco pi[ugrave] montano.