Pollen structure and germination of Crocus thomasii Ten. (Iridaceae)

Abstract

Mature pollen of C. thomasii Ten. (Iridaceae) has been studied from a morphological and physiological point of view and compared to that of C. sativus L., C. thomasii pollen is roundish, with a 83 μm diameter and a 14% of anomalous grains. Percentage of the positive alcoholdehydrogenase (ADH +) pollen grains is about 90% whereas the in vitro germinated rate reaches 55%. Exine is homogeneously thickened (2.5 μm) with randomly distributed thinner zones and 5 μm thick intine. Cytoplasm of vegetative and generative cells is very rich of small and large smooth vesicles and vesicles coated by ribosomes. The generative cell shows a thin ondulated pectocellulosic wall. Its nucleus is intensely fluorescent after treatment with the 4,6-diamidino-2-phenylindole (DAPI) fluorochrome. Although many ultrastructural aspects of the C. thomasii pollen are common in C. sativus. L., C. thomasii pollen is smaller, more regularly structured and germinates in vivo and in vitro in higher percentage than that of C. sativus.     

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.     

Notes on the genus Orobanche in Italy: 3. Taxa described by A. Bertoloni

Abstract

Original material of the 12 taxa described as new by Bertoloni has been examined, and typification of their names is discussed. Lectotypes are designated for 11 of Bertoloni's names, one (O. densiflora Bertol.) had been lectotypified before. Orobanche bicolor Bertol. (non C. A. Mey.) belongs to O. cernua L., O. cruenta Bertol. to O. gracilis Sm., O. stricta Moris ex Bertol. to O. schultzii Mutel, O. thyrsoidea Moris ex Bertol to O. rigens Loisel., O. crithmi Bertol. to O. minor Sm., O. vitalbae Bertol. to O. artemisiae-campestris Gaudin, O. fragrantissima Bertol. to O. lutea Baumg., O. laurina Bertol. to O. hederae Duby, O. yuccae Savi f. ex Bertol. to O. hederae Duby (not to O. minor Sm.), O. centaurina Bertol. to O. litorea Guss. (not to O. artemisiae-campestris Gaudin). O. australis Moris ex Bertol., included by Beck in O. canescens C. Presl, is a good species restricted to Sardinia. O. densiflora Bertol. must not, as is customary, be ascribed to Reuter who republished it later.     

Germination and viability of the pollen of Crocus sativus L

Abstract

Viability and germinability tests were carried out on the pollen of Crocus sativus L., a sterile triploid commonly known as saffron. Pollen taken from dehiscent anthers was examined by means of vital staining and cytochemical techniques in order to detect its viability; germination in vitro was evaluated. From the results obtained it is evident that saffron pollen is viable at a high percentage (65%) but germinates at a very low percentage. Moreover in vitro germination is very slow, and is accompained by numerous morphological anomalies. The low germination of the pollen is due to the triploidy of C. sativus.     

Palynological study of Cupressus sempervirens L. var. pyramidalis and var. horizontalis

ABSTRACT

Cupressus sempervirens L. var. pyramidalis and C. sempervirens var. horizontalis were examined for their pollen morphometry and ultrastructure to verify whether, in addition to phenotype, pollen could also show characteristics useful to discriminate the two infraspecific taxa. C. sempervirens var. pyramidalis compared to C. sempervirens var. horizontalis has mainly larger, subcircular pollen with a higher percentage of apolar and germinating grains, and a wall with thicker intine; the cytoplasm has a greater number of callose-containing vesicles. C. sempervirens var. horizontalis has pollen distributed in five classes of shape. In addition it is smaller and shows a higher percentage of ruptured grains, and a lower percentage of germination in vitro. The cytoplasm contains vesicles rich in callose and also a higher amount of osmophilic bodies. Pollen grains in both varietas contain only one cell at dispersal. The reported differences in pollen morphometry, structure and biology, together with the phenotypic characteristics of the tree, support the validity of two infraspecific taxa.     

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.     

The taxa of Scottish bracken in a European perspective

Summary

In contrast to the traditional view that Scottish Bracken (Pteridium Scop., Hypolepidaceae sensu Page, 1976) is a single, uniform taxon, evidence is presented that two species, each represented by multiple subspecies, are present in Scotland. These belong to two different species complexes within Pteridium, the P. aquilinum complex and the P. latiusculum complex. The P. aquilinum complex is represented by P. aquilinum (L.) Kuhn, with at least three subspecies: subsp. aquilinum, subsp. atlanticum C.N. Page and subsp. fulvum C.N. Page. The P. latiusculum complex is represented by P. pinetorum C.N. Page & R.R. Mill with at least two subspecies, subsp. pinetorum and subsp. osmundaceum (Christ) C.N. Page. Only P. aquilinum subsp. aquilinum is an aggressive weed which is a widespread problem to man; the others are rare. The paper establishes the nomenclatural priorities, typification, taxonomy, morphology, known distribution and ecology of all bracken taxa so far known from Scotland. The typification of P. aquilinum is discussed. There is no conflict between the two lectotypifications of Try on (1941) and Sheffield et al. (1989); both relate to the common bracken of the mid- and southern-latitudes of Europe, for which the existing epithet aquilinum must therefore be retained. It is pointed out that some of the other European taxa of bracken might well also yet be found within the British Isles, as well as, perhaps, other (especially possible diploid) taxa as yet undescribed.     

Il genere Allium L. in Italia. IV. Studio citofotometrico sul granulo pollinico di Allium Chamaemoly L.

Abstract

The genus Allium L. in Italy. IV. A DNA cytophotometric study on the pollen grain of Allium chamaemoly L. — A cytophotometric analysis of DNA contents in pollen generative and vegetative nuclei of Allium chamaemoly L. was carried out. DNA synthesis in both nuclei was confirmed and a lightly higher DNA amount than 2C in the vegetative nucleus was pointed out. An analysis of the Fast-green stainable histones in the generative and vegetative nuclei was also accomplished. While the generative nucleus had a very high content of Fast-green stainable histone, the vegetative one have nearly no stainable histone. The occurrence of DNA synthesis and the very low histone content suggest the vegetative nucleus is functional and biochemically activ. The higher than 2C DNA content supports the possibility of a DNA amplification process including probably the amplification of ribosomal cistrons in the pollen vegetative nucleus.     

Micromorphological observations on leaf and pollen of Capparis L. sect. Capparis (Capparaceae)

Sect. Capparis is represented by a single species, Capparis spinosa L., divided into several intraspecific taxa showing plesiomorphic features and disjunct distributions in the Old World. Leaf surface and pollen features were investigated in the whole group by SEM and light microscope observations. The section is characterized by simple hairs, a reticulate to undulate cuticle, anomocytic stomata surrounded by a peristomal rim, and trizonocolporate, prolate pollen grains. The characteristics of the indumentum appear constant, while the studied taxa are fairly differentiated with respect to cuticular patterns and dimensions of the stomata, and show slight differences in pollen size and exine surface. This micromorphological evidence, coupled with other phenotypic features, supports the placement of this section at the base of the genus Capparis in the paleotropical area. Considering the striking geographic disjunction and symplesiomorphies of the group, its biogeographical and systematic aspects are also discussed.     

Le Infezioni Con “Stubborn” Ottenute per Trauma E Il Grado di Recettività dei Tipi di Grano

Abstract

Dioecy ensures cross pollination but pollen must travel from male to female plants, sometimes covering long distances. The present study concerns the reproductive strategy of two Italian dioecious plants: Mercurialis annua L. and Bryonia dioica L. The former is anemophilous and the latter is entomophilous; the latter has nectar and pollen as rewards. The distribution of pollen grains on the stigma is very different in the two species, reflecting the different types of pollination. In both species there is a number-dependent mechanism of pollen germination on the stigma. This mechanism could enhance male gametophytic competition.     

Studies in Montia L. and Claytonia L. and Allied Genera

The pollen morphology of several genera in Portulacaceae is described. Particular attention has been paid to the genera of the subfamily Montioideae, as a stage of continued monographical studies. Among genera especially dealt with are Claytonia, Montia, Crunocallis, Naiocrene, Neopaxia, Mona, Maxia, Limnalsine, and Montiastrum. In the taxonomical treatment of these genera the pollen morphology has proved to afford many important additional characters.

The pollen grains of Claytonia are distinguished from those of the remainder in being 3-colpate. The grains of the Claytonia-type have many similarities with those of Lewisia, a genus of the subfamily Portulacoideae. The other genera of Montioideae have pantocolpate pollen grains. Among these genera several different pollen types are distinguished, chiefly with regard to the sexine structures and the aperture membranes. The Montiastrum-type is especially interesting, with tholate grains, a particular pollen type not met with in any other genus in the family. The pollen morphology of some genera in the Portulacoideae is also treated. In some species in Calandrina and Talinum pantotreme pollen grains are observed with apertures transitional between pori and colpi. The apertures of the pantotreme grains are arranged in characteristic patterns.

Particular attention has been given to the variation of the pollen morphological characters. This variation has been examined with regard to the differences between different populations of the same species as well as between different species. The greatest variation has been observed in the shape and size of the grains. The structure and sculpture and thickness of the sexine and the aperture membranes are less variable. Some polyploid taxa are connected with the occurrence of pollen grains with divergent and varying aperture numbers.

In a survey of the genera the taxonomical results of the investigation are presented with particular regard to the pollen morphology. The new genus, Maxia Ö. Nilss., is described. One new species, Montia clara Ö. Nilss., is described and some new combinations are made.

Pollen morphological diagnoses are given for 46 different taxa. The aperture conditions for 96 different species are presented.     

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.     

Evolution of apomixis as a strategy of colonization in the dioecious species <Emphasis Type="Italic">Lindera glauca</Emphasis> (Lauraceae)

I have investigated the reproductive biology of four dioecious species of Lindera in Japan: Lindera obtusiloba Bl., L. umbellata Thunb., L. erythrocarpa Makino, and L. glauca Bl. The sex ratios in populations of the first three species are close to equality, but in L. glauca only female individuals are found in Japan, although males are known from continental Asia. The persistence of this dioecious species in the absence of males is surprising, and prompts the question: What mechanisms operate to ameliorate problems of colonization in species of Lindera? I carried out bagging experiments in order to test for apomixis (asexual reproduction by seeds) and to establish the importance of pollination and fertilization, and potential pollen vectors. Only L. glauca reproduced by apomixis. Level of fruit set was high, and was not affected by pollination. In the other three species, seed set was entirely dependent on pollen transfer, which could be accomplished by small Coleoptera and Diptera. The evolution of apomixis in L. glauca appears to have been a strategy to overcome sterility and establish a population in the Japanese islands even in the absence of males. However, this change in breeding system has not occurred in congeneric, co-occurring species, which do not seem to have experienced a lack of male plants.     

Pollen morphology of six species of Bupleurum L. (Apiaceae) present in Sicily and taxonomic implications

Abstract

In this study, using light and scanning microscopes, the morphobiometric characters of pollen grains of Bupleurum fruticosum L., B. fontanesii Guss. ex Caruel, B. gerardi All., B. lancifolium Hornem., B. semicompositum L., B. tenuissimum L. have been analysed. The elaboration of qualitative and quantitative palynological data has allowed us to formulate a key of identification which characterizes six morphotypes. Pollen grains of B. fruticosum (a perennial species) have been distinguished from the grains of the other annual species examined by us on the basis of several morphobiometric characters, a condition which has confirmed the systematic arrangements suggested by several authors. The close palynological affinity between B. tenuissimum and B. semicompositum compared with B. gerardi has supported the placement of these three species in a distinct subsect. of the sect. Eubupleura Briq. or in a distinct subsect. of the sect. Isophyllum (Hoffm.) Dumort. Similarly, our palynological data on B. fontanesii have confirmed the systematic arrangement. However, these data differ from those reported by different authors who placed the three species in the sect. Aristata Godron subsect. Juncea Briq.     

Cytosolic ascorbate peroxidase in some species of the Quercus genus

ABSTRACT

Six species of the Quercus genus (Quercus ilex L., Q. coccifera L., Q. suber L., Q. trojana Webb, Q. macrolepis Kotschy, Q. cerris L.) have been screened for cytosolic ascorbate peroxidase (APX) by means of native polyacrylamide gel electrophoresis (PAGE). A single isozyme was found in five species (Q. trojana, Q. suber, Q. cerris, Q. macrolepis and Q. coccifera), while Q. ilex shows two different APX proteins. The data showed marked similarities among Q. trojana, Q. suber, Q. cerris and Q. macrolepis with respect to the electrophoretic mobility. The validity of APX electrophoretic patterns in systematic studies is discussed.     

New records and a bibliography of the mosses of Pakistan

Abstract

Forty mosses are recorded for Pakistan, of which six appear to be new records for that country. Timmiella subintegra Dix. is reduced to synonymy under T. barbuloides (Brid.) Moenk., and there are notes on the typification of Pilotrichum pluvinii Brid. (Cryptoleptodon pluvinii (Brid.) Broth.).     

‘Seeing’ Atomic Radiations

Miller, Christina G., and Louise A. Berry. Coastal Rescue: Preserving Our Seashores. New York: Atheneum (Macmillan), 1989. 120 pp. $12.95 hardcover. Reviewed by Wayne Hanley.

Marschall, Laurence A. The Supernova Story. New York: Plenum Press, 1988. 296 pp. $22.95 hardcover. Reviewed by Julian R. Brandou.

Young, Steven B. To the Arctic: An Introduction to the Far Northern World. New York: John Wiley &; Sons, 1989. 354 pp. $24.95 hardcover. Reviewed by Emanuel D. Rudolph.

Eldredge, Niles. Life Pulse: Episodes from the Story of the Fossil Record. New York: Facts On File Publications, 1987. 246 pp. $10.95 paperback. Reviewed by Robert G. Hoehn.

Langhorne, M. J., J. O. Donham, J. F. Gross, and D. Rehmke. Teaching with Computers: A New Menu for the 90's. Phoenix, Ariz.: The Oryx Press, 1988. 218 pp. 822.50 paperback. Reviewed by John M. Newell.

VanCleave, Janice Pratt. Chemistry for Every Kid: 101 Easy Experiments That Really Work. New York: John Wiley &; Sons, 1989. 232 pp. $10.95 paperback. Reviewed by Edward L. Shaw, Jr.

Smithsonian Family Learning Project. Science Activity Book: 20 Exciting Experiments for Parents and Kids To Do, (More Science Activities: 20 Exciting Experiments To Do, Still More Science Activities: 20 Exciting Experiments To Do). New York: Galison Books, 1987, (1988, 1989). 96 pp. $9.95. Reviewed by Susan McCarthy.

Summerlin, Lee R., and James L. Ealy, Jr. Chemical Demonstrations: A Source Book for Teachers, Vol. 1 (2d Ed.). 1988. Reviewed by Ann C. Howe and Alice D. Anderson.

Summerlin, Lee R., Christie L. Borgford, Julie B. Ealy. Chemical Demonstrations: A Source Book for Teachers, Vol. 2 (2d Ed.). 1988. Washington, D.C.: American Chemical Society. 197 pp., 233 pp. each $19.95 paperback. Reviewed by Ann C. Howe and Alice D. Anderson.

Berger, Melvin. Atoms, Molecules and Quarks. New York: G. P. Putnam's Sons, 1986. 79 pp. $9.99 hardcover. Reviewed by Harold H. Jaus.

Hersey, Robert L. How to Think with Numbers. Providence, R.I.: Janson Publications, 1982. 133 pp. $795 paperback. Reviewed by C. Bruce Hunter.

Treffert, Darold A. Extraordinary People: Understanding “Idiot Savants.” New York: Harper &; Row, 1989. 291 pp. $17.95 hardcover Reviewed by Elissa Malcohn.     

Pollen viability as a bio-indicator of air quality

Many air pollutants cause plant deterioration. In this study pollen viability was used as bio-indicator of air quality. The study was carried out in the city of Perugia where road traffic is the most important cause of air pollution. Three areas, with different intensity of road traffic (very high, medium and absent) but all characterized by the presence of the same plant species, were selected. Eight species were studied: Hedera helix L., Convolvulus sepium L., Cynodon dactylon (L.) Pers., Quercus ilex L., Dactylis glomerata L., Parietaria diffusa M. et K., Daucus carota L. and Tilia cordata Miller. The pollen of these species was treated with TTC (2, 3, 5 Tryphenil-Tetrazolium-Chloride) staining solution and viability was then estimated by light microscopy. The results showed that the pollen viability was inversely proportioned with pollution. The highest difference in pollen viability between the areas was registered in Tilia cordata. Quercus ilex instead showed that there was no difference in pollen viability between the three different areas. Parietaria diffusa showed a particular behaviour; the highest pollen viability percentage was in polluted areas. The statistical analysis (ANOVA) showed that the main source of variability of the pollen viability depends on the plant but also the site and the interaction between plant and site were very important with a high significant level (p < 0.0001). This revised version was published online in June 2006 with corrections to the Cover Date.