Giuseppe Frenguelli - Academia.edu (original) (raw)

Papers by Giuseppe Frenguelli

Research paper thumbnail of Climatic change in Mediterranean area and pollen monitoring

Flora Mediterranea, 2014

online. The conservation of species in situ is one of the least understood issues of biodiversity... more online. The conservation of species in situ is one of the least understood issues of biodiversity conservation and probably the least addressed. The main general aim and long-term goal of in situ conservation of target species is to protect, manage and monitor selected populations in their natural habitats so that the natural evolutionary processes can be maintained, thus allowing new variation to be generated in the gene pool that will allow the species to adapt to changing environmental conditions. In situ species conservation covers a broad spectrum of activities ranging from the preparation and implementation of detailed single-species recovery plans in the case of species that are critically endangered (which the CBD includes under ex situ conservation), through vigilance and monitoring for those species that are rare, not threatened or only vulnerable, to various forms and degrees of management intervention which affect either the species populations concerned or the habitats/areas in which they occur or both. In situ species conservation is usually contrasted with ex situ conservation but various types of intermediate situations exist which make a transition between the two. An approach that has gained widespread acceptance in some parts of Europe is the establishment of micro-reserves. Globally, most countries have put little if any effort into species conservation although in Europe several countries (including some in the Mediterranean region), as well as North America and Australia have considerable experience of recovery/conservation plans for highly endangered species. Only a small number of management, conservation plans or recovery plans have been published. On the other hand, conservation of forest species in situ is a long-standing tradition and there are lessons to be learnt from this area. As in other parts of the world, it is time to treat in situ species conservation in the Mediterranean as a serious issue that demands an informed, coherent and costed strategy.

Research paper thumbnail of Andamento delle importazioni di piante inserite nelle Appendici CITES durante gli ultimi anni

Research paper thumbnail of Caratterizzazione bioclimatica della città di Perugia

Research paper thumbnail of Allergens as trigger factors for allergic respiratory diseases and severe asthma during thunderstorms in pollen season

Research paper thumbnail of Effect of Cppu (Cytokinin) Treatments on Fruit Anatomical Structure and Quality in Actinidia Deliciosa

Research paper thumbnail of Selenium as stressor and antioxidant affects pollen performance in Olea europaea

Flora - Morphology, Distribution, Functional Ecology of Plants, 2015

Selenium (Se) as an antioxidant is a trace element essential to wellness and the maintenance of h... more Selenium (Se) as an antioxidant is a trace element essential to wellness and the maintenance of human health. Although it has not been confirmed to be an essential micronutrient in higher plants, there is increasing evidence of its benefits in plants in which it inhibits the detrimental effects of environmental stressors, while only few studies refer to its action on pollen germination. Selenium enhances the stress tolerance regulating the production and quenching of reactive oxygen species (ROS); however, the endogenous ROS are essential to the cross-talk between pollen and stigma and promote pollen tube growth. The action of Se has many mechanisms, not all yet fully clarified. In order to deepen the knowledge and fill the gaps in the role of Se as an inhibitor of ROS and, at the same time, a promoter of pollen germination, we attempted this research, enriching olive trees growing in pots and in the field with Se. The plants in pots were kept at a controlled water regime in order to induce drought stress. To test the effect of antioxidant on pollen performance, a single application of Se was supplied to the plants at the beginning of pollen development. Two olive cultivars (Arbequina and Maurino) were used in three different experiments in which Se enrichment was carried out through (i) endo-xylematic drip injection, (ii) foliar spray, (iii) soil application. The pollen performance was assessed at anthesis. The results showed that Se enrichment in non-stressed plants induced a higher rate of pollen viability and germination, but it did not always stimulate their reproductive performance. Different responses were obtained in drought stressed plants, in which Se induced pollen germination, obtaining a performance similar to non-stressed plants. The ROS detection by a quantitative method, applied on hydrated pollen, verified the results just discussed.

Research paper thumbnail of Experimental results about Platanus pollen deposition

A comparison between the aerobiological and floristic data carried out for Platanus are reported.... more A comparison between the aerobiological and floristic data carried out for Platanus are reported. The source was constituted by 60 Platanus trees. When they were pollinating we calculated the total pollen prodution of the source, controlling the number of male inflorescences for each plant, the number of anthers for each inflorescence and the number of pollen for each anther. Aerobiological data were obtained with 16 Durham gravimetric samplers positioned over an area of approximately 25 km 2 at variable distances and in different directions to capture pollen transported by winds coming from any direction. In the first year of analysis, we carried out two kind of aerobiological monitoring positioning a Hirst volumetric trap near the closest gravimetric sampler. The two methods showed a similar trend in Platanus pollen profiles. In the following years, only Durham gravimetric samplers were used to study pollen dispersion. The data showed that there were high concentrations of pollen on the soil near the source while at distances higher than 800 m pollen concentration decreased dramatically. About 1/4 of all the pollen produced fell in an area within 400 m from the source and at a distance of 2750 m only 9 pollen grains/cm 2 fell throughout the entire season.

Research paper thumbnail of Airborne pine (Pinus spp.) pollen in the atmosphere of Perugia (Central Italy): Behaviour of pollination in the two last decades

The phenology of many species, which grow intemperate climate, is principally regulated bythe tem... more The phenology of many species, which grow intemperate climate, is principally regulated bythe temperature and the plants respond withvariations in the beginning, in the durationand in the intensity of the various phenophasestowards every climate change. We ...

Research paper thumbnail of Effects of Cytochalasin B on germinating seeds of Pisum sativum L. Respiration, ultrastructure of cotyledonary cells, storage substances, acid phosphatase activity

Giornale botanico italiano, 1983

Pisum seeds were soaked in water and in Cytochalasin B (CB) for 24 and 48 h, then left in the dar... more Pisum seeds were soaked in water and in Cytochalasin B (CB) for 24 and 48 h, then left in the dark to germinate for 5 days. During this first phase of germination the ultrastructure of the cotyledonary cells was examined, seed respiration was measured, the contents of storage substances and acid phosphatase activity in the cotyledons and axes were separately

Research paper thumbnail of Leaf anatomy in three cultivars of rape (Brassica napus L.) during the ontogenetic cycle

Research paper thumbnail of Microsporogenesis and Dormancy Period in Some Arboreal Species

Giornale botanico italiano, 1996

Research paper thumbnail of Air-borne pollen census in Ascoli Piceno (central Italy) 1983

Giornale botanico italiano, 1985

This paper describes observations on the air-borne pollen concentration in the Ascoli Piceno atmo... more This paper describes observations on the air-borne pollen concentration in the Ascoli Piceno atmosphere in 1983. The pollen grains were collected using Hirst volumetric spore trap. 72 different types of pollen belonging to 47 families were identified. In order to consider the intensity and the lenght of the pollination of the main taxa, the annual pollination has been divided in

Research paper thumbnail of Histological investigation on gall development induced by a worldwide invasive pest,Dryocosmus kuriphilus, onCastanea sativa

Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2014

ABSTRACT The Asian chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is one of th... more ABSTRACT The Asian chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is one of the most serious pests of chestnut trees worldwide. Wasps lay eggs into chestnut buds from mid Jane to late July, depending on latitude, and galls develop the following spring on new vegetation, reducing photosynthesis and nut production. We observed that modification of tissues surrounding D. kuriphilus eggs, which differentiate to form the larval chamber, started approximately 1 month after oviposition, shortly after eggs hatch. The larval chambers continued to increase slightly in size throughout the autumn months until January. After that, a period of stagnation, which corresponds to the plant's dormancy, occurred, followed by rapid growth from March to May, during the period from bud swelling to bud break. Galls continued to grow during the leaf expansion after bud break and stopped when plant organs achieved their final size. Our results have implications for the management of the pest, providing a better understanding of the critical time periods for the effective control.

Research paper thumbnail of Comparison of the Allergenic Potency of Old (1997) and Fresh (2008) Grass Pollens

Journal of Allergy and Clinical Immunology, 2013

Research paper thumbnail of The influence of air temperature on the starting dates of the pollen season ofalnusandpopulus

Grana, 1991

... Mincigrucci a , AH Nikkels b , W. Dankaart c & F. Ferranti a ... M. Spieksma, E. ... more ... Mincigrucci a , AH Nikkels b , W. Dankaart c & F. Ferranti a ... M. Spieksma, E. Bricchi, B. Romano, G. Mincigrucci, AH Nikkels, W. Dankaart & F. Ferranti (1991): The influence of air temperature on the starting dates of the pollen season of alnus and populus , Grana, 30:1, 196-200 ...

Research paper thumbnail of One year of pollen monitoring in an urban network, perugia, central italy

Grana, 1991

Abstract Pollen monitoring at three locations in the area of Perugia is reported for the period N... more Abstract Pollen monitoring at three locations in the area of Perugia is reported for the period November 1988-October 1989. A meteorological station which automatically provided data (temperature, precipitation, relative humidity, direction and velocity of wind), was located beside each trap. The study was correlated with a phenological investigation in urban and rural areas surrounding the traps in order to test the validity of using the results as indicators in a monitoring network. The aerobiological data of the three monitoring stations allows the following conclusions: 1) no notable differences were recorded during the principal period of pollination considering the flowering trends of the local anemophilous flora are taking into account, 2) from a quantitative point of view, values from Central Perugia and West Perugia were higher than those from East Perugia, 3) from a qualitative point of view, the station located in the old city area was characterized by a significant presence of Urticaceae polle...

Research paper thumbnail of Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen

Environmental Pollution, 2011

Air pollution is frequently proposed as a cause of the increased incidence of allergy in industri... more Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O 3) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O 3 fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens. There was decreased pollen viability after O 3 fumigation, which indicates damage to the pollen membrane system, although the ROS and NO contents were not changed or were only slightly induced, respectively. Ozone exposure induced a significant enhancement of the ROS-generating enzyme NAD(P)H oxidase. The expression of the allergen Amb a 1 was not affected by O 3 , determined from the mRNA levels of the major allergens. We conclude that O 3 can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase.

Research paper thumbnail of Airborne pollen content in the atmosphere of central Italy (1982–1986)

Experientia, 1988

Summary This report describes qualitatively and quantitatively the content of pollen in the atmos... more Summary This report describes qualitatively and quantitatively the content of pollen in the atmosphere of central Italy during the five years 1982–1986. Total production in this period showed fluctuations depending on the flowering seasons of the anemophilous taxa. The season of maximum pollen concentration was from April to July, with a prevalence of arboreal pollen in thefirst months, and of

Research paper thumbnail of Time linkages between pollination onsets of different taxa over an 11-year period in Perugia, Central Italy

Aerobiologia, 1995

Times of pollination of different taxa in the atmosphere of Perugia (Central Italy) over an I l-y... more Times of pollination of different taxa in the atmosphere of Perugia (Central Italy) over an I l-year period (1982-1992) were recorded and analysed by means of a 7-day volumetric Hirst-type pollen trap. For some taxa, the pollination period varied from year to year from a chronological and/or quantitative point of view. Several taxa showed a linkage in their starting dates of pollination. Knowledge of this kind of linkage allows us to build a forecasting model.

Research paper thumbnail of A predictive study on the beginning of the pollen season for Gramineae andolea europaea L

Aerobiologia, 1989

On the basis of the results of seven years (1982-1988) of pollen and meteorological monitoring in... more On the basis of the results of seven years (1982-1988) of pollen and meteorological monitoring in the atmosphere of Perugia and Ascoli Piceno (central Italy) beginning of pollen season forecasts for Gramineae and Olea europaea L. are reported. The beginning of the pollen season for grass varied between May 2nd and May 2 7th while for Olea it varied between May 26th and June 23rd. By a statistical analysis of these data several significant correlations were found between the onset of the principal period of pollination and the air temperature in the preceding months and the number of ~(heat units~ required to flower. Utilizing multiple regressions a predictive method of the beginning ofpollen season for both the taxa is reported.

Research paper thumbnail of Climatic change in Mediterranean area and pollen monitoring

Flora Mediterranea, 2014

online. The conservation of species in situ is one of the least understood issues of biodiversity... more online. The conservation of species in situ is one of the least understood issues of biodiversity conservation and probably the least addressed. The main general aim and long-term goal of in situ conservation of target species is to protect, manage and monitor selected populations in their natural habitats so that the natural evolutionary processes can be maintained, thus allowing new variation to be generated in the gene pool that will allow the species to adapt to changing environmental conditions. In situ species conservation covers a broad spectrum of activities ranging from the preparation and implementation of detailed single-species recovery plans in the case of species that are critically endangered (which the CBD includes under ex situ conservation), through vigilance and monitoring for those species that are rare, not threatened or only vulnerable, to various forms and degrees of management intervention which affect either the species populations concerned or the habitats/areas in which they occur or both. In situ species conservation is usually contrasted with ex situ conservation but various types of intermediate situations exist which make a transition between the two. An approach that has gained widespread acceptance in some parts of Europe is the establishment of micro-reserves. Globally, most countries have put little if any effort into species conservation although in Europe several countries (including some in the Mediterranean region), as well as North America and Australia have considerable experience of recovery/conservation plans for highly endangered species. Only a small number of management, conservation plans or recovery plans have been published. On the other hand, conservation of forest species in situ is a long-standing tradition and there are lessons to be learnt from this area. As in other parts of the world, it is time to treat in situ species conservation in the Mediterranean as a serious issue that demands an informed, coherent and costed strategy.

Research paper thumbnail of Andamento delle importazioni di piante inserite nelle Appendici CITES durante gli ultimi anni

Research paper thumbnail of Caratterizzazione bioclimatica della città di Perugia

Research paper thumbnail of Allergens as trigger factors for allergic respiratory diseases and severe asthma during thunderstorms in pollen season

Research paper thumbnail of Effect of Cppu (Cytokinin) Treatments on Fruit Anatomical Structure and Quality in Actinidia Deliciosa

Research paper thumbnail of Selenium as stressor and antioxidant affects pollen performance in Olea europaea

Flora - Morphology, Distribution, Functional Ecology of Plants, 2015

Selenium (Se) as an antioxidant is a trace element essential to wellness and the maintenance of h... more Selenium (Se) as an antioxidant is a trace element essential to wellness and the maintenance of human health. Although it has not been confirmed to be an essential micronutrient in higher plants, there is increasing evidence of its benefits in plants in which it inhibits the detrimental effects of environmental stressors, while only few studies refer to its action on pollen germination. Selenium enhances the stress tolerance regulating the production and quenching of reactive oxygen species (ROS); however, the endogenous ROS are essential to the cross-talk between pollen and stigma and promote pollen tube growth. The action of Se has many mechanisms, not all yet fully clarified. In order to deepen the knowledge and fill the gaps in the role of Se as an inhibitor of ROS and, at the same time, a promoter of pollen germination, we attempted this research, enriching olive trees growing in pots and in the field with Se. The plants in pots were kept at a controlled water regime in order to induce drought stress. To test the effect of antioxidant on pollen performance, a single application of Se was supplied to the plants at the beginning of pollen development. Two olive cultivars (Arbequina and Maurino) were used in three different experiments in which Se enrichment was carried out through (i) endo-xylematic drip injection, (ii) foliar spray, (iii) soil application. The pollen performance was assessed at anthesis. The results showed that Se enrichment in non-stressed plants induced a higher rate of pollen viability and germination, but it did not always stimulate their reproductive performance. Different responses were obtained in drought stressed plants, in which Se induced pollen germination, obtaining a performance similar to non-stressed plants. The ROS detection by a quantitative method, applied on hydrated pollen, verified the results just discussed.

Research paper thumbnail of Experimental results about Platanus pollen deposition

A comparison between the aerobiological and floristic data carried out for Platanus are reported.... more A comparison between the aerobiological and floristic data carried out for Platanus are reported. The source was constituted by 60 Platanus trees. When they were pollinating we calculated the total pollen prodution of the source, controlling the number of male inflorescences for each plant, the number of anthers for each inflorescence and the number of pollen for each anther. Aerobiological data were obtained with 16 Durham gravimetric samplers positioned over an area of approximately 25 km 2 at variable distances and in different directions to capture pollen transported by winds coming from any direction. In the first year of analysis, we carried out two kind of aerobiological monitoring positioning a Hirst volumetric trap near the closest gravimetric sampler. The two methods showed a similar trend in Platanus pollen profiles. In the following years, only Durham gravimetric samplers were used to study pollen dispersion. The data showed that there were high concentrations of pollen on the soil near the source while at distances higher than 800 m pollen concentration decreased dramatically. About 1/4 of all the pollen produced fell in an area within 400 m from the source and at a distance of 2750 m only 9 pollen grains/cm 2 fell throughout the entire season.

Research paper thumbnail of Airborne pine (Pinus spp.) pollen in the atmosphere of Perugia (Central Italy): Behaviour of pollination in the two last decades

The phenology of many species, which grow intemperate climate, is principally regulated bythe tem... more The phenology of many species, which grow intemperate climate, is principally regulated bythe temperature and the plants respond withvariations in the beginning, in the durationand in the intensity of the various phenophasestowards every climate change. We ...

Research paper thumbnail of Effects of Cytochalasin B on germinating seeds of Pisum sativum L. Respiration, ultrastructure of cotyledonary cells, storage substances, acid phosphatase activity

Giornale botanico italiano, 1983

Pisum seeds were soaked in water and in Cytochalasin B (CB) for 24 and 48 h, then left in the dar... more Pisum seeds were soaked in water and in Cytochalasin B (CB) for 24 and 48 h, then left in the dark to germinate for 5 days. During this first phase of germination the ultrastructure of the cotyledonary cells was examined, seed respiration was measured, the contents of storage substances and acid phosphatase activity in the cotyledons and axes were separately

Research paper thumbnail of Leaf anatomy in three cultivars of rape (Brassica napus L.) during the ontogenetic cycle

Research paper thumbnail of Microsporogenesis and Dormancy Period in Some Arboreal Species

Giornale botanico italiano, 1996

Research paper thumbnail of Air-borne pollen census in Ascoli Piceno (central Italy) 1983

Giornale botanico italiano, 1985

This paper describes observations on the air-borne pollen concentration in the Ascoli Piceno atmo... more This paper describes observations on the air-borne pollen concentration in the Ascoli Piceno atmosphere in 1983. The pollen grains were collected using Hirst volumetric spore trap. 72 different types of pollen belonging to 47 families were identified. In order to consider the intensity and the lenght of the pollination of the main taxa, the annual pollination has been divided in

Research paper thumbnail of Histological investigation on gall development induced by a worldwide invasive pest,Dryocosmus kuriphilus, onCastanea sativa

Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2014

ABSTRACT The Asian chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is one of th... more ABSTRACT The Asian chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is one of the most serious pests of chestnut trees worldwide. Wasps lay eggs into chestnut buds from mid Jane to late July, depending on latitude, and galls develop the following spring on new vegetation, reducing photosynthesis and nut production. We observed that modification of tissues surrounding D. kuriphilus eggs, which differentiate to form the larval chamber, started approximately 1 month after oviposition, shortly after eggs hatch. The larval chambers continued to increase slightly in size throughout the autumn months until January. After that, a period of stagnation, which corresponds to the plant's dormancy, occurred, followed by rapid growth from March to May, during the period from bud swelling to bud break. Galls continued to grow during the leaf expansion after bud break and stopped when plant organs achieved their final size. Our results have implications for the management of the pest, providing a better understanding of the critical time periods for the effective control.

Research paper thumbnail of Comparison of the Allergenic Potency of Old (1997) and Fresh (2008) Grass Pollens

Journal of Allergy and Clinical Immunology, 2013

Research paper thumbnail of The influence of air temperature on the starting dates of the pollen season ofalnusandpopulus

Grana, 1991

... Mincigrucci a , AH Nikkels b , W. Dankaart c & F. Ferranti a ... M. Spieksma, E. ... more ... Mincigrucci a , AH Nikkels b , W. Dankaart c & F. Ferranti a ... M. Spieksma, E. Bricchi, B. Romano, G. Mincigrucci, AH Nikkels, W. Dankaart & F. Ferranti (1991): The influence of air temperature on the starting dates of the pollen season of alnus and populus , Grana, 30:1, 196-200 ...

Research paper thumbnail of One year of pollen monitoring in an urban network, perugia, central italy

Grana, 1991

Abstract Pollen monitoring at three locations in the area of Perugia is reported for the period N... more Abstract Pollen monitoring at three locations in the area of Perugia is reported for the period November 1988-October 1989. A meteorological station which automatically provided data (temperature, precipitation, relative humidity, direction and velocity of wind), was located beside each trap. The study was correlated with a phenological investigation in urban and rural areas surrounding the traps in order to test the validity of using the results as indicators in a monitoring network. The aerobiological data of the three monitoring stations allows the following conclusions: 1) no notable differences were recorded during the principal period of pollination considering the flowering trends of the local anemophilous flora are taking into account, 2) from a quantitative point of view, values from Central Perugia and West Perugia were higher than those from East Perugia, 3) from a qualitative point of view, the station located in the old city area was characterized by a significant presence of Urticaceae polle...

Research paper thumbnail of Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen

Environmental Pollution, 2011

Air pollution is frequently proposed as a cause of the increased incidence of allergy in industri... more Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O 3) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O 3 fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens. There was decreased pollen viability after O 3 fumigation, which indicates damage to the pollen membrane system, although the ROS and NO contents were not changed or were only slightly induced, respectively. Ozone exposure induced a significant enhancement of the ROS-generating enzyme NAD(P)H oxidase. The expression of the allergen Amb a 1 was not affected by O 3 , determined from the mRNA levels of the major allergens. We conclude that O 3 can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase.

Research paper thumbnail of Airborne pollen content in the atmosphere of central Italy (1982–1986)

Experientia, 1988

Summary This report describes qualitatively and quantitatively the content of pollen in the atmos... more Summary This report describes qualitatively and quantitatively the content of pollen in the atmosphere of central Italy during the five years 1982–1986. Total production in this period showed fluctuations depending on the flowering seasons of the anemophilous taxa. The season of maximum pollen concentration was from April to July, with a prevalence of arboreal pollen in thefirst months, and of

Research paper thumbnail of Time linkages between pollination onsets of different taxa over an 11-year period in Perugia, Central Italy

Aerobiologia, 1995

Times of pollination of different taxa in the atmosphere of Perugia (Central Italy) over an I l-y... more Times of pollination of different taxa in the atmosphere of Perugia (Central Italy) over an I l-year period (1982-1992) were recorded and analysed by means of a 7-day volumetric Hirst-type pollen trap. For some taxa, the pollination period varied from year to year from a chronological and/or quantitative point of view. Several taxa showed a linkage in their starting dates of pollination. Knowledge of this kind of linkage allows us to build a forecasting model.

Research paper thumbnail of A predictive study on the beginning of the pollen season for Gramineae andolea europaea L

Aerobiologia, 1989

On the basis of the results of seven years (1982-1988) of pollen and meteorological monitoring in... more On the basis of the results of seven years (1982-1988) of pollen and meteorological monitoring in the atmosphere of Perugia and Ascoli Piceno (central Italy) beginning of pollen season forecasts for Gramineae and Olea europaea L. are reported. The beginning of the pollen season for grass varied between May 2nd and May 2 7th while for Olea it varied between May 26th and June 23rd. By a statistical analysis of these data several significant correlations were found between the onset of the principal period of pollination and the air temperature in the preceding months and the number of ~(heat units~ required to flower. Utilizing multiple regressions a predictive method of the beginning ofpollen season for both the taxa is reported.