Ricerche Embriologiche Sul Genere Thalictrum. II. Embriologia e Cariologia Di Thalictrum Lucidum L. e di Thalictrum Minus L. Subsp. Minus

Abstract

Embryological researches in the «Thalictrum» genus. II. Embryology and caryology of «Thalictrum lucidum» L. and «Thalictrum minus» L. ssp. «minus». — In their development the female gametophytes of Thalictrum lucidum L. and Thalictrum minus L. ssp. minus follow the Normal type. In the female gametophytes of these species several types of antipodal cells occurs such as: their considerable enlargement, formation of many antipodals polyploid or polinucleated antipodal cells. In these various types, however, a rapid regression of the antipodals occurs. In T. lucidum some tendency to a disposition of the tetrapolarized type has been verified. The chromosome number has been confirmed to ben 2n=28 in besides, in the pollen development, many cases of regression of the microspores has been verified. The chromosome number has been confirmed to ben 2n=28 in Thalictrum lucidum L., and has been found to ben 2n=14 in Thalictrum minus L. ssp. minus, a new number in this species, which was earlier reported to have 2n=42.     

Ricerche Sullo Sviluppo Embriologico Di Erigeron Speciosus DC. (Compositae)

Abstract

The embryological development of Erigeron speciosus DC. — The Author refers on the embryology of Erigeron speciosus DC. listing the most important characteristics of the development of this gametophyte

a) a pluricellular archesporium is formed, with fertile and sterile cells.

b) several mother cells develop inside a single nucellus leading to the formation more than one gametophyte;

c) at the end of the meiotic process different conditions may be reached; that is: tetramegasporial apocitium; II) trimegasporial apocitium plus a megaspore; III) dimesporial apocitium plus two megaspores at the two ends of the apocitium;

d) the gametophyte may vacuolate with different patterns.

e) different types of development may occur in the gametophyte, that is: I) from tetrasporic cell of a 16-nucleate gametophyte with a monosporial oangium; II) from trisporic cell of a 12-nucleate gametophyte with a monosporial oangium; III) from disporic cell of a 8-nucleate gametophyte with a monosporial oangium.

f) Erigeron speciosus has a cromosomic set of n = 9.     

Ricerche Embriologiche su Senecio Vulgaris L. var. Thyrrenus Fiori

Abstract

Embryological researches on SENECIO VULGARIS L. var. THYRRENUS Fiori. — Male gametophyte, development of tapetal cells and female gametophyte have been studied in Senecio vulgaris L. var thyrrenus Fiori.

1) The development of male gametophyte is normal. Divisions of the microspore mother cells are of the simultaneous type. The division of the generative nucleus has never been observed till the pollen grain was in the anther.

2) The tapetal cells follow a very simple development. The nucleus of each cell divides only twice starting at the same time with the meiotic divisions of pollen mother cells but ending much earlier; subsequently, as usually happens with the Asteraceae, the ameboid involution of the tapetum begins. Endomitosis or any other process which leads to a polyploidy not due to nuclear fusion, has never been observed.

3) The female gametophyte is eight nucleate of the normal type (Polygonum). At maturity it shows only three antipodal cells whose nucleus undergoes at first, two or three divisions. Only later these new nuclei, always within the antipodal cell, may fuse in a polyvalent one.     

Rhodymenia delicatula P.J.L. Dangeard (Rhodophyta,Rhodymeniales) en Méditerranée

Abstract

Presence of Rhodymenia delicatula P.J.L. Dangeard in the Mediterranean. - The presence of Rhodymenia delicatula P.J.L. Dangeard (Rhodophyta, Rhodymeniales) in the southern Thyrrhenian sea is reported. Both cystocarpic and tetrasporic individuals have been collected. Anatomical features of the reproductive structures, as well as the position of these on the thallus allowed the identification of this species formerly known for the Atlantic coasts of Morocco and British Isles.     

STUDIES IN THE VISCACEAE. II. A REINVESTIGATION OF THE FEMALE GAMETOPHYTE OF ARCEUTHOBIUM DOUGLASII

A reinvestigation of the female gametophyte of Arceuthobium douglasii showed that the development conforms to the Allium type (bisporic), and the report of tetrasporic development is erroneous.     

Highly repeated DNA analysis and systematics of the Lemuridae,a family of Malagasy prosimians

Hybridization of highly repeated DNA sequences ofEulemur fulvus mayottensis, Lemur catta, andVarecia has been performed on blots of different species of Lemuridae (L. catta, Hapalemur griseus, Varecia variegata variegata, V. v. rubra, E. macaco macaco, E. coronatus, E. mongoz, andE. rubriventer). The probe ofE. fulvus only hybridized with the differentEulemur species, whereas that ofVarecia hybridized with the two subspecies ofVarecia and that ofL. catta with bothL. catta andHapalemur. These results were used to confirm the classification ofVarecia in a separate genus and to review the separation of theL. catta/Hapalemur group from the other species ofEulemur. Comparison of the migration patterns from DNA fragments of these different species has been used to propose a cladogram of the differentEulemur species.     

Recherches sur le genre Peyssonnelia (Rhodophycées). III. Peyssonnelia crispata sp. nov.

Abstract

Studies on the genus Peyssonnelia (Rhodophyceae). III. Peyssonnelia crispata sp. nov. – A new specie of Peyssonnelia (P. crispata) is described from deep waters (44 to 45 m.) off the mediterranean coast of France.     

Contributo Allo Studio Sistematico ed Ecologico Della Luzula Calabra Ten. dell'Altipiano Silano

Abstract

Contribution to the systematics and ecology of LUZULA CALABRA Ten. of the Silan highland (Calabria, Southern Italy). — The Luzula calabra Ten. represents a known type endemic to the Silan highland.

Some authors regard it as a species in itself, others include it as a variety in the Luzula campestris Lam. et DC. cycle.

Therefore, in view of the fact that the systematic value of this entity has not yet been well defined and that it is not always easy to succeed in attributing isolated specimens to the Luzula calabra Ten., and all the more because information relating to the environment in wich the plant lives is scant and not always reliable, the intention of this work has been to specify, by biometric analysis, the fundamental characteristic of the Luzula calabra Ten., and furthermore to give and adequate picture of the environment in wich the plant lives.

The resultats of statistical analysis and the diagrams ottained show how the Luzula calabra Ten. offers a particular physiognomy of its own and how it stands out from the others in the Luzula campestris cycle.

The environment in wich the plant completes its life cycle is shown in a series of areas in the Silan marshes, occupied by various vegetal groups folloving one another regularly from the wettest part to the driest wich is populated by the Nardus stricta L. and the Festuca rubra asperifolia St. Yves.

In Sila the presence of two Luzule of the Luzula campestris cycle is identified: the Luzula calabra Ten., wich must be considered almost surely as a species in itself, and the Luzula campestris Lam. et DC. ssp. vulgaris Buchen; on the other hand, the presence of the Luzula campestris Lam. et DC. ssp. multiflora Buchen is thought unlikely, and this is considered to be a form peculiar to high pasture-lands of the strictest alpine-mountain type.     

Sulla cariologia del Genere Carlina L.

Riassunto

L'A. ha studiato i cariogrammi di 6 specie italiane del genere Carlina L. (C. gummifera Less. var. Fontanesii (DC.) Fiori, C. acaulis L. var. alpina (Jacq.) Fiori, C. acanthifolia All., C. lanata L., C. vulgaris L., C. carymbosa L.).

Il corredo cromosomico è 2n = 20 per tutte le specie. Per la presenza di un gruppo di cromosomi della lunghezza superiore a 4 μ nelle specie a grossi capolini, si rende possibile distinguere auche cariologicamente nel genere Carlina L. due sezioni, corrispondenti alla possibile distinzione morfologica delle Carline in Macrocefale (C. gummifera Less. var. Fontanesii (DC) Fiori, C. acaulis L. var. alpina (Jacq.) Fiori, C. acanthifolia All., C. latana L.) e Microcefale (C. vulgaris L. e C. eorymbosa L.).     

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.     

Ricerche Cito-Embriologiche E Distribuzione Geografica di Cirsium Casabonae Lam. ET DC. (Compositae)

Abstract

Cyto-embryological study and geographical distribution of CIRSIUM CASABONAE Lam. et DC. — The mature megagametophyte of Cirsium Casabonae Lam. et DC. (Compositae) is eight nucleate of the normal or Polygonum type.

In the nucellus there is only one megaspore mother cell. After meiosis the three micropylar megaspores degenerate. The three antipodal cells start to degenerate as soon as the gametophyte reaches maturity. Microsporogenesis is regular.

The chromosome number of Cirsium Casabonae Lam. et DC. is 2n = 32. This shows that also in Europe, as in America, there is at least one species of Cirsium with basis number × = 16.

The study of the geographical distribution of Cirsium Casabonae Lam. et DC. shows it to be an Atlantic-West Mediterranean endemism.     

Osservazioni embriologiche,sistematiche ed ecologiche su Allium parciflorum Viv.

Abstract

Embryological, systematic and ecological observations on Allium parciflorum Viv. The morphological observations and the comparison with some allied species have shown a good taxonomic isolation of Allium parciflorum: this has suggested to ascribe it to a new section.

It has been observed that the female gametophyte develops according to the disporic-type, as in other species of Allium previously studied.

The distributional area in Sardinia has been considerably extended and many ecological data are also given.     

Evoluzione Annuale della Cerchia Legnosa in Individui Maschili E Femminili di Ginkyo Biloba L.

Abstract

Wood ring evolution in male and female plants of GINKYO BILOBA L. — A morphological examen of the wood rings in Ginkyo biloba L. has been performed on stem sections from specimens of the Botanical Institute of Florence, on wood samples from the collection of Adriano Fiori and on wood cores extracted from the stem of male and female plants growing in the Botanical Garden of Florence.

At the same time the development of the growth ring has been followed on wood samples tacken off the stems of two adult Ginkyo plants growing in the Botanical Garden of Florence.

All the material which has been studied shows the same characters, that is the frequency of uncomplete crescent-shaped wood rings, and consequently a large degree of eccentricity of the stems, depending not only upon the uncomplete wood rings, but also on the changing width of each ring.

Microscopical analysis has pointed out the presence of false rings, limited by discontinuous late wood, particularly in the female plant. This character has been observed only in a fossil wood of Ginkyo bonesii.

It has not been possible to assers how many rings or crescents are formed during one year. From dating records made on wood cores it seems that more than one ring could differentiate during one year, but the cambium shows a very irregular activity in Ginkyo. The factors which control the formation of false and uncomplete wood rings (wood crescents) are also unknown; their formation possibly depending upon environment conditions.

External factors such as water deficiency probably control cambial activity through auxin production. Larson (1964) has shown that draught causes a decrease in tracheids diameter, and the formation of false growth rings; thus the same causes could have been in action in our plants.

Noteworthy are also the data by Gungkel and Thimann (in Larson 1964) showing that auxin content increases downwards in the shoots of Ginkyo and that the apical bud has a very low auxin production, so that it seems possible that in Ginkyo the leaves supply something which the cortical tissue converts into auxin.

Lastly, the almost continuous growth activity of the cambium in Ginkyo must be pointed out, this causes a great difficulty in checking the beginning and the end of this process along the year. It is any way possible to establish the time of the highest cambial activity, which lies in June-July both in the female and in the male plants.     

Sull'embriologia di Leontopodium Nivale (Ten.) Huet ex Hand. Mazz.

Abstract

Embryology of « Leontopodium nivale » (Ten.) Huet ex Hand.-Mazz. — As in « Leontopodium alpinum » Cass. var. a typicum Fiori e Paoletti, from different alpine localities, no cases of apomixis have been observed (Maugini 1962) while Sokolowska-Kulczycka (1959) has noticed this phenomenon in the same species collected on the Tatra mountains, an embryological research on « Leontopodium nivale » (Ten.) Huet ex Hand. Mazz. has been undertaken. The material, collected in the alpine garden of Campo Imperatore (Abruzzo), has shown that the development of the female gametophyte occurs as in Leontopodium alpinum, according to the normal monomegasporial type which leads to the formation of an 8-nucleate gametophyte which at maturity is almost always poliantipodate. In « Leontopodium nivale » there is no trace of apomixix, but many cases of degeneration, particularly in the mature gametophyte, have been observed.     

Sulla variabilità cromatica dei fiori nelle specie di Crocus L. delle Alpi sudorientali italiane

Abstract

Chromatic variability of tepals in species of Crocus L. of South-eastern Alps.—The anthocyanidins causing the color of tepals of some species of Crocus L. in the Italian South-eastern Alps were determined and characterized. The genus Crocus of this region is represented by four entities: C. napolitanus Mord. & Loisel., C. albiflorus Kit. ex Schult., C. reticulatus Stev. ex Adam. and C. weldenii Hoppe ex Baker.

The distribution of anthocyanidins in the four entities confirms the existence of a systematic distance among the species belonging to Reticulati and the species belonging to Anulati. Two anthocyanidins, i.e. delphynidin and petunidin, which are always present in other entities, have not been found in C. weldenii; this species is characterized by the only presence of malvidine.

The anthocyanidins assume therefore in this case a chemotaxonomic meaning.     

Chemosystematic Studies on Thalictrum L. in China

According to chemical constituents, plant morphology and geographic distribution of Thalictrum in China, the relationships among sections in the genus are discussed in the present paper. The results show: 1. China is one of the major distribution centers of Thalictrum plants, with half of species endemic. Compared with species in other regions of the world, Chinese ones are relatively primitive. 2. From the chemosystematic point of view, the system of the genus adopted in Fl. Reip. Pop. Sin. is reasonable. 3. The main constituents of Thalictrum plants are benzylisoquinoline alkaloids. A correlation exists between the chemical patterns and plant evolution. The different sections are of different structure types. Aporphine-benzylisoquinoline and bisbenzylisoquinoline are major constituents in Sect. Leptostigma. Sect. Tripterium contains mainly aporphines, but non-alkaloid compounds are principal constituents in several species. In Sects. Thalictum and Schlagintweitella and Subgen. Leconyerium, types and content of alkaloids increase obviously and thus there are medicinal species. So these sections should be interested in developing some active constituents of antitumor, hypotenstion and antibacterium. 4. The genus occupies a special position in Ranunculaceae, as a transition to link the follicle plants and achene plants. Meanwhile, because the genus is rich in benzylisoquinoline alkaloids, the opinion that the Ranunculaceae, Berberidaceae, Menispermaceae andPapaveraceae form a natural group is even more strongly supported.     

Ricerche Cariologiche e Embriologiche Sul Genere Rudbeckia (Asteraceae)

Summary

The author describes the different modalities of the cellularisation of the adult gametophyte of Rudbeckia laciniata L. The several cases are arranged according to the number and the type of differentiation of the cells of the gametopyte. Of each type it is stated the frequency, calculated in about 500 cases.

The author remarks that the differentiation of the single cells is owing to »an effect of the position«, which exists in the displacement of the nuclei of the gametophyte regarding the proendospermatic cell, to which cell, however, one can attribute a pre-eminent »power of organization«. The displacement of the nuclei is after all the consequente of the stage of the » polarisation «.     

Morfologia fiorale embriologia ed embriog in Leontopodium alpinum Cass. var. α typicum fiori e Paoletti

Abstract

FLOWER MORPHOLOGY, EMBRYOLOGY AND EMBRYOGENESIS OF LEONTOPODIUM ALPINUM CASS. VAR. α TYPICUM FIORI E PAOLETTI. — The present work has been carried on with capitules of L. alpinum var. α typicum, included and dissected, differing thus from the previous research which is also summarised (BEAUVERD 1909 a e b, 1910, 1012, 1913 a e b, 1914).

The results are the following: all capitules of the same corymb of this species have the same structure, differing eventually in details. Generally they show outwards a few female flowers, inwards a relevant number of pseudohermaphrodite flowers (the sterile hermaphrodite of BEAUVERD). They are therefore subdioecious capitules with tendency to reduce the already scarce number of female flowers. Both female and pseudohermaphrodite flowers have been extensively described. Some rare hermaphrodite flowers with ovules and anthers, and very rare subhermaphrodite without ovules and empty or almost empty anthers have been also observed.

On the same material, embryological and embryogenetical research has been carried out: from it results that the microsporogenesis proceeds normally, without degeneration. The megasporogenesis and the development of the female gametophyte and the formation of an 8-nucleate have been observed and also several cases of poliantiopody. Many gamethophytes at this stage degenerate; the others develop particularly transversally; the antipodes completely degenerate and the secondary nucleus and the egg cell reach remarkable size. Synergids at this stage appear more or less completely fessurate, in their micropilar part.

Fertilisation occurs through porogamy, the zygote producing a bicellular proembryo which goes on dividing while the nucleus of the endosperm forms a cellular albumen.

The embryological and embryogenetical observations do not completely agree with those made by SOKOLOWSKA-KULCZYCKA (1959) on specimens of L. alpinum collected on the Tatra mountains (Carpathian Mts.), where the tetrad often degenerates and only exceptionally brings to the constitution of an aphid gamethophyte. More frequently apomixis has been observed, which implies a parthenogenetical development of the egg cell.     

Embryology and embryogenesis of Spiranthes L.C.M. Richard (Orchidaceae): S. spiralis (L.) Cheval and S. aestivalis (Poiret) L.C.M. Richard

Abstract

The various stages of female gametophyte development and embryogenesis in S. spiralis and S. aestivalis are described. In both species the reproductive cycle is sexual. Some peculiarities are present: the female gametophyte is usually 6-7-8-nucleate; after double fertilization a single endospermatic cell is formed; the proembryo appears differentiated and is made up of different cells in the chalazal and micropylar ends; a single basal cell in the proembryo acts as suspensor.