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.     

Anomalie Anatomiche NEL Legno DI Rami DI Ciliegio Sottoposti a Defogliazione

Summary

The Author studies the secondary wood in a Cherry tree «Regina del Mercato» and describes several degenerative factures in the wood elements.

The author concludes that there is a close relation between number and development of the leaves and differentiation of secondary wood elements.     

Ciclo Di Accrescimento E Differenziazione Delle Gemme in Piante Perenni Nel Territorio Di Bari

Abstract

The secondary wood of the fig tree is characterized by a remarcable degree of dimorphism and the concentric rings d o not correspond to yearly recurring growth periods. These false rings are formed by alternating tangential strips of fibers and wood parenchima. During each vegetative season three or four of these strips arc laid down by the cambium.

During the year the cambium undergoes a period of activity and a period of rest, but there is no histological difference between the early wood and the late one, differentiated just before the restring period. In consequence the so-called annual wood rings do not exist in the fig tree stem.     

Size,shape and sex differences in three subspecies of Black-tailed Godwits Limosa limosa

ABSTRACT

Capsule: Black-tailed Godwits Limosa limosa show sexual size dimorphism and size differences between the subspecies. The shape varies slightly between the subspecies, but not between the sexes.

Aims: To investigate whether and how the three subspecies of Black-tailed Godwits, and the sexes of these subspecies, differ in size and shape.

Methods: We collected body dimensions (lengths of the bill, total head, tarsus, tarsus-toe and wing) of adult Black-tailed Godwits from three locations (Iceland, the Netherlands and northwest Australia) corresponding to the breeding or wintering grounds of three known subspecies (islandica, limosa and melanuroides, respectively). Determining sex by molecular assays, we computed degrees of sexual size dimorphism. Using principal component analysis (PCA), we compared differences in size and shape among the different subspecies.

Results: The limosa subspecies was the largest and also showed the most significant sexual size dimorphism. Sexual size dimorphism was smallest for wing length and largest for bill length. The first two axes of the PCA that included all subspecies of both sexes explained 94% of the total variation. Most body dimensions were highly correlated with each other, but wing length varied independently of the other dimensions. Males and females differed only in size (the first axis). However, one of the two small subspecies, islandica, also differed in shape (the second axis) from limosa and melanuroides.

Conclusions: In all three subspecies of Black-tailed Godwits, females are larger than males. The fact that subspecies differed in the degree of size dimorphism and slightly in shape hints at sex-related differences in the ecological selection pressures between the different flyways.     

Ciclo di Accrescimento E Differenziazione Delle Gemme in Piante Perenni Nel Territorio di Bari

Summary

Growth cycle and buds differentiation in perennial plants growing in Bari's area. — V. The evolution of the wood ring in Rhammus Alaternus L. from December 1946 to March 1949.

In Rhamnus Alaternus L. the cambium awackens in March with the production of an early wood, characterized by large vessels and loose fibers. It keeps on dividing the following months, producing intermediary wood, whose vessels become narrower and narrower. In June the wood ring is almost complete and the cambial activity slows down. In July late wood is formed, with narrow tracheae and highly lignified fibers. From August to February cambial activity is very scarce and irregular, in the wood produced fibers being tangentially compressed.

In a young branch of R. A. cambium becomes suddenly active in February, that is one month before than in the stem, it goes on during the month of March-June, with an evident diminution in the size of the wood elements. This diminution of size instead of being regular, shows some oscillations, expecially during the month of May. In Sept. the cambium starts again dividing, but rather poorly and irregularly, forming some vessels a little wider than the preceeding ones, so that an incomplete false ring is formed only in some points of the branch. As a rule the autumn wood is a typical late wood. This scarce and irregular cambial activity goes on also during Oct.-Dec. In January is more active and forms rather wide vessels in comparison with those formed in the preceeding month. This new formed wood however does not show the characteristics of the early wood of a new ring.

Concluding, the characteristics of the cambial activity of A. R. are

In the stem: 1) March: early wood. 2) March-June: intermediary wood. 3) July: late wood, resting period. 4) At the end of Autumn a scarce production of late wood is sometimes possible.

In the young branch: 1) February: early wood. 2) March-June: intermediary wood, with positive and negative oscillations in the vessels width. 3) At the end of June the late wood is already differentiated. 4) July-August: resting period. 5) Spt.-Juan.: the cambium starts again dividing very scarcely and producing a transition wood between the two rings. This wood can be regarded neither as a true ring nor a false one, it represents rather the last phase of the late wood formation. 6) In the young branch of the female specimen the cambium starts dividing somewhat later than in the male one. 7) The wood ring width does not vary much in relation to the yearly amount of rainfall. The lack of relation between rainfall and ring width is particularly evident in 1948 (a rainy year). The, «Compleasance» of R. A. could show that this species is, in Puglia, in its own habitat. On the other hand it is rather peculiar that R. A. forms only one wood ring during one year, with production of early wood during the spring, and of late wood in the autumn, instead of producing a second autumn ring following a distint summer rest, as could be expected.     

Additions To The Flora Of Shetland

ABSTRACT

Background: Pallenis spinosa (Asteraceae) produces both winged and wingless achenes. Both achene morphs are non-dormant and show a similar embryo size, rendering dispersal ability as their only apparent functional difference.

Aims: We studied morph-specific release and spatial dispersal patterns to ascertain whether the common view of seed dimorphism as a mixed strategy, that is functionally fully differentiated morphs, is appropriate for this system.

Methods: For three years, at the onset of achene release, in early autumn, we placed achene traps at different distances from source plants, censusing achene arrival at 3–4 day intervals. We constructed morph-specific dispersal kernels and related release intensity to prevailing meteorological conditions in census intervals. Selected kernel models were used to describe dispersal effects of observed changes in the proportion of winged achenes (p_w) in successive released fractions.

Results: Achene release extended up to early-mid winter, peaking in rainy, windy intervals. Throughout the season, p_w decreased progressively. Unexpectedly, the wingless morph produced the longest dispersal tails and it only showed ability for fat-tailed dispersal. Consequently, maximum dispersal distances steadily increased throughout the season.

Conclusions: Achene dimorphism in P. spinosa appears to allow a within-season continuous reshaping of the seed-dispersal kernel instead of representing a mixed strategy.     

Early season temperature controls cambial activity and total tree ring width at the alpine treeline

Background: Temperature directly affects xylogenesis at high-elevation treelines. The low-temperature limitation of meristematic processes is thus key to understand treeline formation.

Aims: We aimed to experimentally test in situ the direct low-temperature effect on wood tissue formation at the alpine treeline.

Methods: We applied controlled Peltier-mediated cooling and warming (±3 K) to branch segments in Pinus uncinata at the treeline in the Swiss Alps. In addition, we studied xylogenesis in untreated trees during the growing season by sequential micro-coring.

Results: Micro-cores indicated that the cambial zone was fully developed by the time the cooling and warming treatment started, shortly after snowmelt. Presumably, because of this, experimental cooling of branches did not significantly reduce the number of cells produced per season. Warming extended the formation of early wood into the late season, and thus reduced the fraction of late wood.

Conclusions: We conclude that temperatures very early in the season determine the width of the cambial zone which, in turn, strongly controls the number of tracheids produced during the remaining growing season. Temperatures later in the season mainly determine the early wood to late wood ratio. These data provide an empirical basis for the mechanistic understanding of tree growth at the treeline in response to temperature.     

Le Plantule Della Flora Trapanese

Summary

Secondary wood growth in both a ♂ and a ♀ plant of Schinus Molle has been studied in Bari, Puglia.

The bulk of the secondary wood has been found to be made up of substitution fibres full of starch grains, which it would be more appropriate to call fusiform wood parenchyma cells (according to the « Glossary of Terms Used in Describing Woods», in Tropical Woods, N° 36, 1933).

There are no annual rings: the thickening is due to the addition of successive «growth layers», 3 or 4 per year.

The cambium does not undergo any evident resting period, neither in summer nor in winter, but only periods of suspended activity: the periods of suspended activity do not occur simultaneously in the ♂ and ♀ plants, but in different months.

Each period of cambial activity passes through the three stages of initial, maximum, and decreasing intensity and lasts for 2–3–4 months depending on the season and the sex.

Tipically the growing period starts with the deposition of new elements; next follows lignification of these same elements; during the third stage starch grains appear in the fusiform and radial parenchyma cells of the newly formed wood.

During 1952, 4 growth layers have been formed in the ♂ and 3 in the ♀ plant. In general each episode is slower and more diluted in time in the ♀ plant as compared to the ♂ one. A diversity in cambial behaviour as regards spring reawakening, between the two sexes of dioiceous plants had been already observed in Rhamnus Alaternus (De Paolis, 1949); in both species the ♂ plant appears to be more sensitive and more speedy in its reactions than the ♀ one.

The author does not know of any research on cambial activity in S. Molle carried out in Peru, the native land of this species. Comparing its cambial activity as revealed by the present researches with that of other evergreen plants spontaneous in Puglia the existence of an essential difference is demonstrated: while in S. Molle cambial activity is subcontinuous, in the Mediterranean evergreen trees and shrubs so far studied the cambium undergoes two resting periods, one in winter, and a more or less well defined one in summer. Moreover cambial activity in S. Molle can be taken as continuous if the plants of both sexes are considered, owing to their asinchronism (the same phenomenon happens in flowering times). This lack of a well defined growth cycle corresponds to a similar lack of a well defined seasonal cycle in the climate of the interandine Peruvian valleys, the original habitat of S. Molle, where the mean temperatures of the coldest months vary from 5,8° C to 11,9° C, while those of the hottest months vary from 10,3° C to 15,9° C, with yearly excursions of 4,5 to 5° C.

On the other hand the type of secondary th ckening by successive apposition of wood layers recalls closely that of a group of Mediterranean plants studied in Puglia, that is Ficus carica (Giannuoli, 1949), Olea europaea (Armenise, 1950), and Phillyrea latifolia (Maranò, 1953). In the case of these species the authors had suggested that they belonged, or were related to genera which had originated or developed in regions lacking a well defined seasonal climatic cycle. This hypothesis is confirmed by the fact that S. Molle, a recently imported tropical plant has maintained in our Mediterranean climate not only its original type of secondary thickening, but also its original growth rythm. S. Molle can be considered an experimental test of an hypothesis based so far on the interpretation of observation data.     

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.     

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.     

Differenze Morfologiche ed Anatomiche in Individui Maschili E Femminili di Ginkyo Biloba L.

Abstract

Anatomical and histological differences between ♀ and ♂ plants of GINKYO BILOBA L. — Morphological characters in several ♀ and ♂ specimens of Ginkyo have been checked, with the aim to put in evidence those which are sex-linked. Anatomical data from a previous research have been utilized. (Maugini 1965).

The main results are here summarized.

In the climate of Florence the female plants unfold their buds in the first ten days of April, the male ones in the middle of March, so that the males break their dormancy about one month before the females.

From the buds opening, brachyblasts are formed both in males and females, and catkins and ovules appear. At the beginning of May, the ovules have considerably grown, and catkins are faded. In the meanwhile the leaves have completely grown up in both sexes. Between the end of September and the beginning of October, the seeds become gold-yellow and begin to be shed off. Dissemination may go on for a long while, and still be active when all the leaves are fallen.

Buds are formed during summer, they are very little and sharp in the female, round and bigger in the male.

In both sexes leaves turn yellow and begin to fall between the end of October and the beginning of November. Females are generally considered more precocious than males in shedding leaves, but this behaviour did not result constant in the plants under observations so that the « leaf-fall time » cannot be considered a sex-linked character.

In shoots and stems of males and females, proceeds downwards tracheid deposition and differentiation, the highest activity being in the brachyblasts, where cambium works continuosly, and the lowest in the stem, where late wood formation can be found only in the male plants. Unevenness of cambial activity along the plant axis is particularly evident in the female, where late wood formation in the stem is rare.

The rhythm of cambial activity along shoots and stems of males and females have been compared with that of the buds, with the following results: both in the female and male plants the young leaves start expanding about two months before cambium activity starts in the stem. The male plant is more precocious than the female, probably the slower vegetation rhythm of the female being related to the seed ripening process.     

METAL UPTAKE AND ALLOCATION IN TREES GROWN ON CONTAMINATED LAND: IMPLICATIONS FOR BIOMASS PRODUCTION

Phytostabilization aims to reduce environmental and health risks arising from contaminated soil. To be economically attractive, plants used for phytostabilization should produce valuable biomass. This study investigated the biomass production and metal allocation to foliage and wood of willow (Salix viminalis L.), poplar (Populus monviso), birch (Betula pendula), and oak (Quercus robur) on five different soils contaminated with trace elements (TE), with varying high concentrations of Cu, Zn, Cd, and Pb as well as an uncontaminated control soil. In the treatment soils, the biomass was reduced in all species except oak. There was a significant negative correlation between biomass and foliar Cd and Zn concentrations, reaching up to 15 mg Cd kg^?1 and 2000 mg Zn kg ^?1 in willow leaves. Lead was the only TE with higher wood than foliage concentrations. The highest Pb accumulation occurred in birch with up to 135 mg kg ^?1 in wood and 78 mg kg ^?1 in foliage. Birch could be suitable for phytostabilization of soils with high Cd and Zn but low Pb concentrations, while poplars and willows could be used to stabilise soils with high Cu and Pb and low Zn and Cd concentrations.     

Studio Del Ritmo Vegetativo Di Olea Europaea L. in Messina Negli Anni 1952–54

Summary

The vegetative growth of the olive tree in Messina is described. The growth period begins at the end of March and prosecutes without interruption as late as November. The secondary wood tissue producted during summer time (from Yuly to August) is abnormal being of a parenchimatoide type. During winter there is a well defined rest period.

The cambium produces secondary wood and bark with an alternate rythm, so that in spring the wood production prevails on the liber and in autumn the opposite condition is realized.

Each phase of production of secondary conducting tissues (wood as well as bark) is followed by a phase of starch storing.

In the stem several false wood rings are produced during one year, while in the young branches each wood ring corresponds to one year.

The longitudinal growth and cork formation on the branches of the year are particularly pronounced during spring (March-May).

Cambium cells swell in a characteristic way before they start dividing and collapse during the resting periods, thickening evidently their walls, so that in winter it is difficult to distinguish a cambial cell from a parenchimatic one.

The behaviour of the vegetative growth of the olive tree in Messina is discussed on the base of the climatic characters of the region.     

Ciclo Di Accrescimento E Differenzazione Delle Gemme in Piante Perenni Nel Territorio Di Bari

Summary

The evolution of cambial activity during one year in Viburnum Tinus L. in Bari has been studied. The research seems to be particularly difficult in this evergreen shrub. The wood is of the porous diffused type with scarse evidence of wood rings. The vessel diameter varies rather irregularly in the wood ring; on the other side the fibers show wide variations and may be assumed as a good index of the wood ring evolution. Both in the branch and in the stem only one wood ring each year is formed.

Cambial activity prosecutes during the whole year, with an irregular step. During the period July-beginning of September the cambium devides very slowly, or possibly stops deviding.

The early wood is produced earlier in the branch than in the stem; namely in February-end of May in the branch and in March-beginning of June in the stem. The stimulating growth stuffs evidently proceeds downwards from the top to the base of the plant. The relations between ring evolution and climatic factors are discussed. The peculiar cambial poussée during the month of June seems to be correlated with the exceptionally aboundant rainfall of May in Puglia in 1947.

The late wood is formed during the other months discontinuosly. The alternation between the two phases of cambium division and wood lignification has been focussed. The wood ring in Viburnym Tinus is annual and the early wood differentiates in spring.     

L'evoluzione della cerchia legnosa in Arbutus Andrachnoides Link. in Firenze,dal luglio 1946 al Giugno 1947

Summary

The evolution of the wood ring in arbutus andrachnoides link, in florence (from July 1946 to June 1947).

The anatomical characters of the wood ring of the stem and of the young branch of Arbutus andrachnoides Link have been studied in Florence.

The results are the following: the cambial tissue in the stem starts dividing at the end of April and continues during the summer months, ending completely in September.

In the branch the cambium differentiates almost a month earlier, namely at the beginning of April.

In both cases the only wood ring produced is completed at the end of September. Comparing the evolution of this wood with the climatic factors it can be seen that the cambium activity starts in a period of remarkable rainfall and of regular increase of temperature and presents a remarkable activity still at the end of August.

Arbutus andrachnoides Link. is a spontaneous hybrid between A. Unedo and A. Andrachne and its distribution (in Greece and in the gréek islands) shows that A. Unedo and A. Andrachne had the possibility to overlap in this area and to produce this hybrid.     

Linking small-scale topography with microclimate,plant species diversity and intra-specific trait variation in an alpine landscape

Background: Small-scale topographic complexity is a characteristic feature of alpine landscapes, with important effects on alpine plant distribution.

Aims: We investigated the links between small-scale topographic complexity and resultant microclimatic heterogeneity, vascular-plant species richness and beta diversity, and realised niche width and trait variation of some target species.

Methods: We recorded temperature and soil moisture within 10 sites (40 m × 40 m) of differing topographic complexity in alpine terrain at Finse, Norway (N 60° 36?, E 7° 33?). Plant species occurrence and traits of target species were recorded in 16 sample plots at each site.

Results: Sites differed significantly in microclimatic heterogeneity, and topographically rough sites were always more heterogeneous than flatter ones. Greater species richness and turnover was associated with greater microclimatic heterogeneity, and rough sites contained 15–55% more species than flatter ones. Plant species had on average wider realised niches when growing at rough sites. Individuals of Bistorta vivipara, but not those of Luzula spicata, tended to exhibit greater phenotypic variation at rough sites.

Conclusions: Rough alpine terrains create small-scale variation in microclimate, promoting species richness and beta diversity. In the event of climate change, small-scale microclimatic heterogeneity might allow plant species to escape from regional climate change by short-distance migration to local micro-refugia. This study suggests that the opportunity for such responses would be greater in topographically complex terrains.     

Ulteriori Osservazioni Sulla Variabilità Del Legno Secondario in Prunus Persica Stokes

Abstract

Further observations on the variability of the secondary wood of PRUNUS PERSICA Stokes. — The length of both fibres and vessel members and the age of cambium in the trunk of a wild specimen of Prunus persica are positively correlated; no relation exists between the length of the above mentioned elements and the width of growth layers.

The relation between the intrasive growth of fibres and either age of cambium or width of growth layers has been also calculated but no significant relation has been attained.

The results have been compared with those obtained in the previous study of a trunk of a grafted Prunus persica, which are very different and quite peculiar mainly as to a decrease in length of fibres and vessel members with aging of cambium. The growing practice to which the tree may have been subjected is regarded as the possible cause of this peculiarity.     

The urban woods of Rome (Italy)

ABSTRACT

A phytosociological study of the urban woods of Rome is described. Six syntaxonomical types were identified: 1) Orno-Quercetum ilicis, an edaphic-xerophytic variant of the natural potential vegetation of the city (deciduous Quercus sp. pl. woods); 2) Aquifolio-Fagetum carpinetosum betuli, in the northern slopes of alluvial valleys; 3) Q. suber and Q. pubescens wood, ranked in Quercetalia pubescenti-petraeae order 4) Quercetum ilicis galloprovinciale suberetosum; 5) coppice of Q. cerris and Q. frainetto, which belongs to the Teucrio siculi-Quercion cerridis alliance; 6) mixed mesophile wood of Q. cerris and Ostrya carpinifolia which can be considered a transition between the Doronico-Fagion and the Teucrio siculi-Quercion cerridis alliances. All of these six woody vegetation types are characterised by the large penetration of Mediterranean species belonging to the Quercetea and Quercetalia ilicis and the middle-European ones of the Querco-Fagetea. This mosaic of species exemplifies the bioclimatic characteristics of Rome, which is situated in a Mediterranean transitional region.     

Prove DI Degemmazione Nel Pesco E Loro Effetti Sulla Istogenesi della Cerchia Legnosa

Summary

Tests on disbudding and their effects on the histogenesis of the wood ring. In this work the effects of hormonic character which appear during the histogenesis of the wood ring have been studied testing disbudding effects on the peach tree.

Some observations on the consequences due to defoliation are also included.

By removal of the buds, the annual ring shows a greater depth and a more marked uniformity of structure, due to an increased frequency of the vascular elements.

By removal of the leaves, the cambial activity is completely inhibited. These results are attributed to the fact that the leaves, according to the more recent hypotheses, produce the substance which stimulates the formation of the wood elements and the differentiation of the newly formed elements.

This inactive substance, produced by the leaf, would exert its action only when the buds, towards which it is directed, transform it into its active form. The removal of the buds would eliminate the centres of diffusion of the inactive substance and also its centres of activation and concentration for the coming rest period, in view of a new vegetative cycle.

As a conseguence the circulation of the inactive substance is more marked, as it is probably activated by the cambium, and its activity lasts longer, producing in the annual ring those characters peculiar to the spring wood, that is of a season in which the circulation of this substance is at its utmost.