Evoluzione Della Cerchia Legnosa in Quercus Aegilops L. a Tricase

Abstract

The author has examined the cambial activity and the formation of the annual ring in Quercus aegilops from February 1954 to February 1955. Material was collected at Tricase (Lecce) the only Italian locality where this oriental species grows although it is doubtful whether it is spontaneous.

Cambial activity starts in the middle of April both in the main stem and in the branches following flowering and bud development. It goes on for about five months until the second half of August forming a complete growth ring. This annual ring shows the normal sequence of early wood with wide vessels formed during the second half of April and the whole of May, intermediate wood with medium and small size vessels, parenchima, and fibres formed in June-July, and late wood with few small size vessels, parenchima, and fibres formed from the end of July to middle August.

There is no reawakening of cambial activity in autumn even if the climatic conditions are favourable. Tylosis are very easily formed in the wood vessels and by this process the plant can withstand the drought of the Apulian summer.     

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.     

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 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.     

Stomata on the Primary Root of Ceratonia siliqua

Anomocytic stomatal complexes observed with light and scanningelectron microscopes on the primary roots of Ceratonia siliqua(carob tree) are described. Stomata are randomly distributedthroughout the surface of the root zones which possess maturevascular tissues, i.e. from the zone of root hairs to the transitionzone. Stomatal orientation does not follow that of the rootepidermal cells whilst their distribution does not seem to forma regular pattern. Ceratonia siliqua, primary root, stomata     

THE DEVELOPMENTAL BASIS FOR SEXUAL EXPRESSION IN CERATONIA SILIQUA (LEGUMINOSAE: CAESALPINIOIDEAE: CASSIEAE)

The flowers of Ceratonia siliqua, an anomalous caesalpinioid legume in the tribe Cassieae, are unusual in being unisexual and in lacking petals. Inflorescence development, organogeny, and flower development are described for this species. All flowers are originally bisexual, but one sex is suppressed during late development of functionally male and female flowers. Ceratonia siliqua is highly plastic in sexuality of individuals, inflorescence branching pattern, racemose or cymose inflorescences, bracteole presence, terminal flower presence, organ number per whorl, missing floral organs, pollen grain form, and carpel cleft orientation. Order of initiation is: five sepals in helical order, then five stamens in helical order together with the carpel. Each stamen is initiated as two alternisepalous primordia that fuse to become a continuous antesepalous ridge; in some flowers, the last one or two stamens of the five may form as individual antesepalous mounds. Petal rudiments are occasional in mature flowers. Position of organs is atypical: the median sepal is on the adaxial side in Ceratonia, rather than abaxial as in most other caesalpinioids. This feature in Ceratonia may be viewed as a link to subfamily Mimosoideae, in which this character state is constant.     

Root hydraulic conductance of six forest trees: possible adaptive significance of seasonal changes

ABSTRACT

Root hydraulic conductance (K_R was measured in terms of the ratio of volume flow through roots (F) and to the pressure (P) driving the flow in six forest trees growing in habitats characterized by different water availabilities Le. Acer campestre L., Castanea sativa Miller, Fraxinus ornus L., Fraxinus oxycarpa Bieb., Ceratonia siliqua L. and Olea oleaster Hoffmg. et Link. Measurements were made in May, August and November 1996. K_R as normalized for unit leaf surface area (K_RL), was higher in species growing in humid environments (A. campestre and C. sativa) than in others (C. siliqua and O. oleaster) typical of aria zones. A. campestre and C. sativa showed declining K_RL values from spring to autumn while the latter had highest K_RL values in summer. This is in agreement with the typical drought avoidance strategy of C. siliqua which is based on large water losses balanced by equal water uptake from the soil. Plots of F and of A (leaf surface area) to K_RL as well as annual percent changes in F, A_L and K_RL suggest that changes in K_RL are mainly due to analogous changes in F, except for O. oleaster where opposite balanced changes in F and A_L contributed in maintaining the K_RL constant from August to November.     

A phi Layer in Roots of Ceratonia siliqua L

The central cylinder of the primary root of the carob tree (Ceratonia siliqua) is encircled by a layer of cells with wall thickenings, known as a phi (φ) cell layer. The development of the φ layer and the chemical composition of the cell wall thickenings have been studied in roots of C. siliqua. The results reveal the presence of condensed tannins in the mature phi thickenings and that the development of the φ layer is asynchronous: at 0–1 cm from the root tip φ thickenings appear before endodermis differentiation at the sites opposite phloem, at 1–4 cm new φ thickenings are developed at the sites opposite xylem, at 4–7 cm the φ layer consists of two layers of cells and it completely encloses the central cylinder.     

Esperienze Di Estivazione Su Urginea Maritima Bak.

Abstract

Aestivation experiments on URGINEA MARITIMA Bak. — Bulbs of Urginea maritima Bak. have been subjected to artificial aestivation in different months (March, April, May, June) in order to find out the most appropriate period for forced blossoming. The bulbs, once taken out of the soil, have been kept for a whole month at 28° C, with atmospheric humidity not strictly controlled but never falling below 48%.

Aestivation in March and April, when the plant is in its full vegetative activity, caused suppression of the sexual phase. Aestivation in May, when the vegetative activity of the plant is approaching its end, caused total flowering anticipated of about 20 days. Aestivation in June, when the plant is at the beginning of its resting period, had no effect on flowering.

These results seem to show that the leaves create in the course of their activity the necessary conditions for flowering and that this critical stage is reached, in the plants under examination, between April and May.

In the plants treated in May that is after they had reached the critical stage, the flowering was not suppressed; on the contrary it occurred earlier than in the plants left in their natural habitat. The advancement of the time of flowering corresponded more or less to the anticipation of the artificial as compared with the naturally occurring aestivation.     

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.     

Antifungal activity of Moroccan medicinal plants against citrus sour rot agent Geotrichum candidum

Aims: The aim of this work was to find an alternative to the chemical fungicides currently used in the control of Geotrichum candidum, the causal agent of citrus sour rot. Methods and Results: Minimal inhibition concentrations (MIC) and minimal fungicidal concentrations (MFC) were determined using agar dilution method. The methanol extracts of Cistus villosus, Ceratonia siliqua and Halimium umbellatum exhibited strong antifungal activity with MIC values ranged between 0·156 and 1·25 mg ml^?1, and MFC values ranged between 2·5 and 5 mg ml^?1. Incidence of sour rot was lowered to 0·00, 3·33 and 11·66% when mandarin fruit was treated with C. villosus, C. siliqua and H. umbellatum methanol extracts at 50 mg ml^?1, respectively, compared with 95% in the control. Conclusions: Cistus villosus, C. siliqua and H. umbellatum methanol extracts successfully reduced the disease incidence caused by G. candidum, and no phytotoxic effects were recorded on citrus fruit. Significance and Impact of the Study: These findings suggest that C. villosus, C. siliqua and H. umbellatum plants may be useful and effective agents for control of citrus sour rot. Such natural products therefore represent a sustainable alternative to the use of synthetic fungicides.     

Osservazioni Sull'attività Cambiale Di Nerium Oleander L.

Abstract

Observation on the cambial activity in «Nerium oleander» L. — The cambial activity of «Nerium oleander» has been observed in three localities in Southern Italy: Bari and Lucera, where the oleander is cultivated, and Policoro, in the bed of the river Sinni, where the oleander is spontaneuos. The wood is of the diffuse-porous type. Growth rings corresponding to distinct periods of growth are not distinguishable, as there are no easily distinguishable types of wood (early, intermediate, and late wood). Only occasionally the uniform wood is interrupted by narrow circular bands of a few layers of radially compressed cells. Differences in the behaviour of the cambium have been observed in the three localities. At Policoro there was a long period of activity from the middle of March until November without interruptions. At Bari the cambium was active from the middle of March until the first days of April; after a pause it was active again from the second half of May until die middle of July and again during the second half of September-October and the first ten days of October. In 1957 a slight activity was noticed also during about twenty days in December. At Lucera the active period as compared with Policoro was still shorter than at Bari; in the spring there was a delay in the resumption of activity, while the summer rest period lasted until the middle of October. The cambium was then active again until the first days of November. Some of the differences in the behaviour of the cambium in the three localities could perhaps be explained by climatic or pedologic factors, such as the rich water table in the case of the plant growing in the Sinni bed. In conclusion «N. oleander» seems to be a species adapted to a sub-tropical climate, without distinct growth rings.     

A late Holocene pollen diagram from the Megaris,Greece, giving possible evidence for cultivation of<Emphasis Type="Italic"> Ceratonia siliqua</Emphasis> L. during the last 2000 years

A late Holocene pollen profile from the Megaris on the eastern Gulf of Corinth shows a vegetation which was strongly influenced by human impact throughout. A Pistacia-Phillyrea maquis, which is reflected in the older parts of the profile, changed later to a more degraded vegetation type. In the uppermost part Pinus dominates the pollen spectrum. A continuous record of Ceratonia siliqua pollen older than cal a.d. 100 is of special interest.     

Leaf surface characteristics and wetting in Ceratonia siliqua L.

Compound leaves of Ceratonia siliqua L. (carob tree) exhibit a long life span and are exposed to environmental stimuli for approximately twenty months. The micromorphology of the adaxial and the abaxial leaflet surfaces was studied, in comparison with treated waxless epidermises (after the removal of cuticle and epicuticular waxes) and corresponding replicas, respectively. The microstructural surface features are evaluated as possible consistent parameters related to the wetness of leaves. The abaxial leaflet surface is more hydrophobic than the adaxial leaflet surface in C. siliqua, which may be particularly important for the ecophysiological status of its hypostomatic leaves.     

Wood anatomy of some trees with diffuse- and ring-porous wood: Some functional and ecological interpretations

Abstract

The xylem conduit dimensions (i.e. their width and length) have been measured in 1-year-old internodes, nodes and node-to-petiole (N-P) junctions of three species with diffuse-porous wood, namely Ceratonia siliqua L., Laurus nobilis L. and Olea europaea L. as well as of three species with ring-porous wood, namely Quercus ilex L., Q. suber L. and Q. pubescens Willd‥ The xylem conduit diameter and length distributions have been related to the drought resistance strategies adopted by the six species. C. siliqua and Q. ilex (drought avoiding water spenders) showed the widest xylem conduits (each species within its characteristic pattern of wood anatomy). This is consistent with their high demand of efficient water transport to leaves. L. nobilis (drought avoiding water saver) showed relatively narrow xylem conduits, efficient enough, however, to assure water supply to leaves at the reduced transpiration rate exhibited by the species. O. europaea, Q. suber and Q. pubescens (drought tolerants) showed the narrowest xylem conduits but also the longest ones. The xylem system of C. siliqua and Q. ilex represented a good compromise between efficiency and safety of the water transport, the former as due to wide xylem conduits, the latter to the reduced xylem conduit length as well as to the strong «hydraulic constrictions» at their nodes and N-P junctions. The ecological interpretation of such hydraulic architecture is discussed.     

The first use of morphologically isolated arbuscular mycorrhizal fungi single-species from Moroccan ecosystems to improve growth,nutrients uptake and photosynthesis in Ceratonia siliqua seedlings under nursery conditions.

The carob tree (Ceratonia siliqua L.) is an important component in semi-arid Mediterranean ecosystems, particularly in Morocco where it plays a considerable socio-economic role. This species is widely used in the reforestation programmes and in the rehabilitation of degraded soils serving both environmental and socio-economic objectives. In spite of these assets, this species is suffering the particular climatic conditions, rare and irregular rains, long hot and dry summers, generally, leading to desertification processes. To withstand these contrasting conditions, selected arbuscular mycorrhizal fungi (AMF) were tested for their contribution to the growth, nutrient uptake and photosynthesis improvement of the carob tree C. siliqua under nursery conditions.The objective of this study was, to evaluate the effects of some arbuscular mycorrhizal fungi complexes isolated in different Mediterranean ecosystems compared to single-species isolates selected using morphological tools on the growth, mineral nutrition, and chlorophyll content of C. siliqua seedlings.The results indicate that all the used AMF inocula stimulated significantly the height of C. siliqua seedlings after eight months under nursery conditions. An increase in plant height between 33% and 70% compared to a control without inoculation was recorded. Similarly, the aerial dry weight recorded an increase of 62% to 124% comparing inoculated and non-inoculated seedlings. The root dry weight has shown an increase rate of 24% to 86% compared to the control. The analysis of mineral contents in plant tissues, showed a highly significant increase in P. N. K. Ca and Mg levels of the aerial parts compared to the control. A significant increase in chlorophyll contents was noticed when inoculated seedlings were compared to non-inoculated ones. This study had confirmed the importance of AMF improving the growth of C. siliqua seedlings; the AMF complexes remain to have the important growth and mineral nutrition responses. However some single- species have shown similar magnitude to the complexes for all analysed parameters. A large biofertilizer potential of the single-species isolates in the inoculation of C. siliqua is demonstrated for the first time.     

Cambial activity and annual rhythm of xylem production of elephant apple tree (<Emphasis Type="Italic">Dillenia indica</Emphasis> Linn.) in relation to phenology and climatic factor growing in sub-tropical wet forest of northeast India

The interrelationship between phenological events, climatic factors, periodicity of cambial activity and seasonal production of xylem was examined in Dillenia indica L. (Dilleniaceae) growing in sub-tropical wet forest of Meghalaya state, India. The reactivation of cambial activity was seen in the first week of May, 15 days after sprouting of new leaves and buds. The activity of cambium and xylem production gradually declined toward December and ceased from January to April end. There was correlation between leaf fall and cambial dormancy. It was evident from the correlation and regression analysis, the relationship between cambial activity, xylem production with climatic factors, the monthly mean minimum temperature plays an important role for the cambial activity and xylem production rather than influence by rainfall and relative humidity in D. indica L. The data were discussed in the light of cambial activity, xylem production and phenological events.     

Genome size microscale divergence of <Emphasis Type="Italic">Cyclamen persicum</Emphasis> in Evolution Canyon,Israel

Using DAPI flow cytometry, we examined genome size divergence of the Persian violet, Cyclamen persicum (Primulaceae) (2n=48) on close opposite slopes of Evolution Canyon (EC), Mt. Carmel, Israel. The range of genome size variation detected among measured cyclamens was 6.41% in relation to the smallest measured DNA content. Our data on C. persicum at EC showed that local variability in the 2C-value exists. Significantly less DNA was recorded in plants growing in one station of the African savannah-like south-facing slope (AS) but not in the remaining two stations of the same slope. We were not able to reject the null hypothesis that there are no significant interslope differences in the genome size between the temperate European garrigue-like north-facing slope (ES) and the drier AS. In spite of the nonsignificant interslope trend for the higher genome size in C. persicum, the data-fusion (meta-analysis) test using correlations between C-values in C. persicum, and earlier studied carob tree (Ceratonia siliqua), trifoil (Lotus peregrinus) and a beetle (Oryzaephilus surinamensis) and their distribution along the aridity gradient indicates a positive relationship between drought and genome size at the microsite.     

Observations botaniques dans des orangeraies abandonnées

Conclusions phytogéographiques et écologiques Nos observations démontrent que les terrains légers de la plaine littorale ne sont pas seulement aisément reconquis par la flore indigène qui se compose d'éléments méditerranéens, steppiques-orientaux et désertiques africains; ils permettent aussi le développement plus ou moins normal d'espèces ligneuses subspontanées à distribution pantropique (Ricinus, Dodonaea), sud-américaine (Schinus, Lantana etc...) et australienne (Acacia) à condition que leurs caractères biologiques de dissémination et de germination permettent leur établissement et qu'elles soient résistantes à la sécheresse estivale prolongée.

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Summary Observations in abandoned citrus groves near Rehovot led to the conclusion that, in the course of 20–25 years, climatic biocenoses of the light soil belt, as Helianthemetum elliptici and the Eragrostis bipinnata-Centaurea procurrens association are reproduced. The starving trees are replaced by indigenous and exotic shrubs and climbers, the former often of a leafless or thorny appearance. Of special interest is the spontaneous expansion of arboreal indigenous species, like Retama roetam, Zizyphus spina christi, Ceratonia siliqua and exotic ornamentals, such as Lantana camara, Schinus terebinthifolius and Acacia cyanophylla, the latter two forming dense natural stands. Distribution by birds plays a major role in the replacement of the citrus trees by species better adapted to the semi-arid surroundings.

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