Elena Maugini

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...

Further Investigations on the Karyotype of Several 40 Chromosome Dwarf Bearded Irises (I. Chamaeiris Bertol. S.L.)

SUMMARYThe investigation of Iris chamaeiris Bertol. s.l. (Maugini and Bini Maleci 1973), is extended to other specimens from Morteto (Ponte a Moriano—Lucca).Following certain general observations, the karyotype of these plants is described in detail. Most of them show a normal karyotype, but two of them show an abnormal one. The two karyotypes observed in the specimens from Morteto are compared with each other and each of them is also compared with the previously studied karyotypes from M. Morello, M. Argentario and Quercianella-Le Forbici.The chromosomal instability of I. chamaeiris s.l. is revealed and justified both by the active vegetative reproduction and by the probable hybrid origin of these plants.

Karyotypes of Male-Fertile and Male-Sterile Iris Pallida Lam. Growing in Tuscany

SUMMARYIris pallida Lam. is widespread in Tuscany where it is mostly cultivated for commercial purposes. Most of the plants observed are male-sterile. Particular attention was given to the Irises cultivated in Caspri (Castelfranco di Sopra—Arezzo) where malesterile and male-fertile plants, as well as a third type called « dentaroli », all grow together. According to the local farmers, « dentaroli » are characterized by lack of flowers. Plants, mostly of the male-sterile type, from areas other than Caspri were examined.The karyotype presents 4 chromosome groups characterized by centromere position (Fig. 1). Male-fertile individuals and « dentaroli » types possess the same normal karyotype. Malesterile specimens instead possess a heteromorphous pair 4, where one chromosome has a regular submedian centromere, while the centromere of the other chromosome is in a median position. The large number of specimens observed, makes it likely that the heteromorphous pair 4 is characteristic of all male-sterile individ...

Observations on Certain Plastids of the Ovule of Ginkyo Biloba L.

SUMMARYAs reported in the literature for several groups of algae and for certain cells of higher plants, among which the endosperm (CAMEFORT and SCHAEFFER 1965) and the oosphere of Ginkyo biloba L. (CAMEFORT 1965), the authors observe that there is also often a contiguity between endoplasmic reticulum and plastids in the tapetum and in the central cell of the archegonium of this plant. The functional significance of this relationships is hypothesized. Moreover, the authors note that in the central cell and in the coenocytic pro-embryo the outer membrane of the plastidial wall bears some evaginations that extend into the cytoplasm. These evaginations seem, in certain cases, to connect two plastids in the central cell, for which it is thought that their formation is due to a particular scission process of the plastids themselves.

On the Megasporogenesis in Larix Leptolepis (Sieb. et Zucc.) Gordon (Pinaceae)

SUMMARYThe mature megasporocyte of various gymnosperms appears as a clearly polarized cell. With reference to the genus Larix Miller (Pinaceae), previous LM observations showed the presence of starch accumulations in the chalazal cytoplasm in L. occidentalis. A peculiar polarization, characterized by the presence of «reticular plasma» in the micropylar cytoplasm, and by a noteworthy abundance of starch in the chalazal region, has been observed in L. sibirica. The present TEM study examines the differentiation of the megasporocyte and the behaviour of the organelles during meiosis in L. leptolepis (Sieb. et Zucc.) Gordon. The most important results are the presence of abundant perinuclear RER complexes in the micropylar cytoplasm of the mature megasporocyte—such a finding can clarify the «reticular plasma» observed in L. sibirica—and the localization of the majority of the mitochondria and amyliferous reserves in the chalazal cytoplasm. It follows that the four megaspores produced by meiosis have different...

Cytological Site of Glycogen in Nostoc Commune Vaucher

SUMMARYIt has been put into evidence by electron microscopy with the technique of Hanker, Seaman, Weiss and others (1964) the presence of glycogen in the cells of Nostoc commune Vaucher and it has been observed its disappearence with a pretreatment of the cells with diastase solutions at different concentration and for different lenghts of time.Glycogen had been already observed in Nostoc commune through the Bauer reaction, PAS, PAS pretreated with diastase and PAS and dimedone (Maugini 1966).

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 ...

Leaf phloem alterations in two provenances ofAbies alba Miller (silver fir) during ageing

The phenomenon of premature needle senescence in two Italian provenances of silver fir was studied as part of a more general research project on decliningAbies alba. The two provenances showed a different degree of sensitivity to atmospheric pollutants. Comparative observations on 1-, 3-, 5-, 7- and 9-year-old needles from both provenances highlighted a faster loss of function in the phloem of needles from the Vallombrosa provenance. This fact appears to be related more to a loss of function in the cambium, than to a different rate of degeneration of sieve cells. This phenomenon may help explain why needles of the Vallombrosa provenance tend to be shed sooner than those of the Serra San Bruno provenance.

Osservazioni sul ciclo di sviluppo delle gemme di esemplari mascbili e femminili di Ginkyo biloba L.

Abstract Observations on the development cycle of the buds of male and female specimens of Ginkyo biloba L. – A study of the buds of long shood and short shoot of male and female Ginkyo biloba L. individuals reveals the following: 1) All the buds of the male individuals are bigger and round in shape while those of the female individuals are smaller and conical. 2) Among individuals of the same sex there are no differences between the buds of long and short shoots except that the latter are always bigger. 3) All the buds, both male and female, show a constant number of buds scales (7–14), embryonic leaves (3–7) and leaf primordia (3–4). 4) The increase in diameters is greater in the male than in the female buds. 5) When opening, the buds of the male short shoots can get as big as 11,5 mm × 11,5 mm and those of the female short shoots 5 mmx4 mm. At this time, the long shoots of both sexes show a less marked differences in size (♂ 5 mm × 5 mm; 9 4 mm × 3,5 mm). 6) The male buds of both long and short shoots ...

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.