Alcune Stazioni di Taxus Baccata L. Nel Gruppo del M. Fumaiolo

Summary

The Author gives details of the station of the jew-tree (Taxvs baccata L.) identified in the region of Mount Fumaiolo. He draws attention to the importance of such findings, allied to what is already known, to the study of plant geography in the Italian peninsula, extending the hope that the caracteristic coniferous pine, rightly considered as a survingin from former times, would be protected, where it grows spontaneously, as evidence of Italian paleoclimatic conditions.     

Le alghe epilitiche di alta montagna nel gruppo del cevedale

Riassunto

Sono state prese in esame 37 stazioni delle rocce scistose del Cevedale fra i 2100 e i 3000 metri con una flora algologica di ben 176 specie. I diversi tipi di roccia posseggono biocenosi caratteristiche secondo il umidità, l'altitudine, l'esposizione e la struttura chimico-fisico.

Forme specifiche del clima alpino non si conoscono con sicurezza causa la diffusione operata dal vento e l'effetto mitigatore dell'acqua stessa alle accentuate oscillazioni termiche del clima alpino.     

Polline fossile di Aesculus aff. hippocastanum L. nel Bacino di Leffe (Pleistocene inferiore). Posizione sistematica e significato paleoecologico

Abstract

Fossil pollen of Aesculus aff. hippocastanum L. in the Leffe Basin (Early Pleistocene). Systematic position and palaeocology. A new pollen analysis has been undertaken in the lacustrine and palustrine deposits of Leffe (Northern Italy), in order to re-evaluate the flora, the vegetation dynamics and the climatic change at the southern margin of the Alps during the lowermost Pleistocene.

The present paper deals with the systematic position and the ecology of a fossil taxon of Aesculus discovered in the Leffe sediments. The taxonomical approach is based on a comparative investigation on the pollen morphology of all the present-living species and the fossil taxon from Leffe. Some diagnostic features of the apertures and the exine ornamentation allowed to distinguish some groups, almost coincident with the sections in which the genus is presently subdivided.

The pollen morphology of the taxa which belong to the sections living in temperate regions and in the subtropical-tropical SE-Asia (section Calothyrsus Koch) notably differ.

Among temperate groups, the Section Aesculus can be characterized by having the biggest projections on the colpus membrane. The fossil pollen from Leffe sediments can be related with this Section. Moreover, a comparison of the Japanese living species (A. turbinata Bl.), with the European one (A. hippocastanum L.), indicates that the fossil pollen grains from Leffe may be related to A. hippocastanum. This supports the hypothesis of a Neogene divergence of a pontic-european group inside the Section Aesculus in agreement with the macrofloral record of the Neogene in Europe. Afterwards the palaecology of the Leffe horse-chestnut is discussed. A comparison between fossil pollen spectra and the analogues in the modern vegetation (Colchide, Mesia, Caucasian region and Allegheny Mountains, U.S.A.) shows good relationships in the floral composition.

Finally, the extinction time of some elements of the Colchic-Hyrcanian flora in Italy during the Quaternary is discussed.     

Uno studio citofotometrico delle proteine durante la mitosi nel meristema radicale di Allium cepa L.

Abstract

A cytophotometric study of proteins during mitosis in root tip meristematic cells of «Allium cepa L.». — Spectrophotometric analyses of the amount of Fast-green stainable proteins at different pH values (8,1; 6; 4; 2) have been accomplished in Allium cepa root tip meristematic cells during the four phases of mitosis. The results seem to indicate that: a) the highest absorption is detectable in correspondence of metaphase at each of the four pH values; b) the transition from prophase to metaphase is characterized by an increase of both proteins reacting at pH 8,1 (histones) and between pH 6 and pH 8,1 (neutral proteins); c) the transition from metaphase to anaphase is characterized by a loss of histones and of proteins reacting between pH 4 and pH 6 (acid proteins); d) the transition from anaphase to telophase is characterized by a loss of neutral proteins. The data are discussed in relation to the problem of chromosome coiling.     

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.     

Note floristiche e fenologiche nel territorio di Arneo (Fra Taranto e Gallipoli)

Summary

The author describes the vegetation and phenology of a Quercus Ilex wood in the Comprensorio dell'Arneo, betwen Taranto and Gallipoli along the eastern shore of the Ionian Sea (Golfo di Taranto). The wood consists partly of a degraded bushy vegetation.

The wood was visited eleven times during the year and each time species found flowering were noted (Table at pp 296–301): the greatest number of them, many being therothytes, was found on April 21rst (fig. 2) with about a month's delay in comparison with Palestine (Gindel). In May there is a considerable i decrease in number of species flowering. In summer and winter, because of drought and low temperature very few species, mostly geophytes, were found flowering, and only slightly but markedly more in Autum.     

Nuove Stazioni di Festuca Laxa Host in Territorio Italiano e Considerazioni Sistematiche Sulla Sua Indipendenza Da Festuca Dimorpha Guss

Abstract

New localities of «Festuca laxa» Host in the Italian territory and systematic considerations about its indipendence from «F. dimorpha» Guss. Some new localities of Festuca laxa are given for the Alps of Friuli (Northeastern Italy), which show that this species takes part also of Italian Flora. Until now it was known only for Austria and Jugoslavia. The paper furthermore deals with some anatomical differences in the leaf — structure of the two fescues, as to see in transections. F. laxa has normally 3 larger vascular bundles, which are wholly enclosed by T-shaped sclerenchyma and 4(8–9) smaller veins, where the sclerenchyma occurs only in the abaxial face of the blade. F. dimorpha on the contrary has 5 larger bundles and usually 6 smaller ones. The number of the secondary veins depends in both cases on the various sizes of the leaves. Also the cenotic and ecological behaviour of F. laxa is shortly illustrated on the basis of two phytosociological records.     

Inibitori nel Sarcotesta del Seme di Ginkgo Biloba E loro Azione Rallentatrice Sullo Sviluppo dell'embrione

Abstract

Inhibitors in the sarcotesta of GINKGO BILOBA seeds and their retarding action on embryo growth. — The sarcotesta of Ginkgo biloba seeds contains some inhibitors which delay or hamper the germination of other cormophytes seeds. This has been proved with seeds of Hordeum vulgare L., Vicia sativa L., and Triticum vulgare L. germinating in water extracts of ripe sarcotesta at various concentrations.

Water extracts of ripe sarcotesta at various concentrations have an anti-mitotic action on root apices of Allium cepa L., resulting in a marked preprophasic inhibition, chromosome stickiness, more or less evident c.-metaphases, and other effects. The water extracts were kept at their original pH (4–4,2) or alkalinized up to a pH of 6,4–6,6.

Indirect statistical evidence, which appears to be highly significant if tested with Student's t, shows that: i) in the seeds of Ginkgo themselves these inhibitors delay embryo development; ii) in the individual seeds of a same plant the inhibitory capacity of the sarcotesta affects embryo development at an earlier or later stage depending on how soon the sarcotesta ripens; iii) the action of the sarcotesta on the embryo decreases with a decreasing water content of the former.

The seeds of Ginkgo biloba do not go through a dormant phase but germinate as soon as the embryo is fully developed. It was already known that temperatures not sufficiently high have a retarding action on embryo growth in this species. This fact together with the presence of inhibitors in the sarcotesta can be interpreted as a biological defense against the danger of the seeds germinating in autumn and the seedlings or young plants dying during severe winter condition.     

Ulteriori ricerche sulla germinazione di Cercis siliquastrum L. Azione dell'acido gibberellico e ruolo dell'endosperma nel fenomeno della dormienza

Abstract

Further research on the germination of Cercis siliquastrum L. Effect of gibberellic acid (GA₃) and role of endosperm in dormancy.—In order to locate the causes of the dormancy in Cercis siliquastrum L., researches have been carried out also on non-scarified seeds without integument, as well as on isolated embryos.

We have noted that gibberellic acid can substitute the cold treatment to interrupt the dormancy and we have also investigated the optimal concentrations.

The results we have obtained do not show the inhibition to be located in the integument and point out a determinant role of the endosperm.

Histological investigations are being carried out to study better the possible occurrence of a mechanical restraint imposed by the albumen on the non-dormant embryo.     

Saxifraga sponhemica Gmel. im Fichtel-Gebirge

Ohne Zusammenfassung     

Saxifraga Forsteri Stein

Ohne Zusammenfassung     

Polygonum nepalense Meisn. avventizia nel Bellunese

Abstract

Polygonum nepalense Meisn. has been found naturalteed together with Collomia linearis Nutt. near Belluno, Northern Italy. Polygonum nepalense belongs to the Cephalophilon-Section, an annual with creeping-ascending branched stems, winged petioles and 2 rounded, basal auricles, leaf-blade ovate-triangular, somehow fleshy, ochreas tubular with a tuft of hairs at the base, peduncles glandular-pubescent; spikes globose, densely flowered, styles 2 (seldom 3), nutlets trigonous, dark-brown, about 1-1.5 mm long. This species has not been indicated yet in the Alps but is cited as a rather common one in humid localities, damp woods in mountains, tea- and chinchona-plantations in Asia and India. Abundant on the Himalaya up to 10,000 ft., known also in Bengal, Ceylon, Assam, Burma, China, Java, Formosa, Japan and Abyssinia.