摘要:

Effects of boron and molybdenum on the growth of Asparagopsis armata (Rhodophyceae, Bonnemaisoniales) in culture. - The influence of two trace-metals (boron and molybdenum) on the growth ofAsparagopsis armatahas been studied in culture. This alga is very tolerant of molybdenum at high concentrations, while boron rapidly becomes toxic.

ISSN:0017-0070    

DOI:10.1080/11263509009428145

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Stomatal features and ontogeny of stomata of 11 ornamental taxa of monocotyledonous families with Agavaceae (1 species), Amaryllidaceae (1 species), Araceae (3 species), Cannaceae (1 species), Commelinaceae (3 species), Liliaceae (1 species), and Musaceae (1 species) have been studied. Features like stomatal area, leaf area occupied by stomata and per cent leaf area occupied by stomata are reported for these taxa for the first time.

ISSN:0017-0070    

DOI:10.1080/11263509009428146

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The present paper details the results of a phytosociological study onVaccinium myrtilluscommunities in the Monti Reatini (Central Apennines). A comparison is reported withVacciniumcommunities from the rest of the Italian peninsula (already described), showing the coenological and syntaxonomical autonomy of the Monti Reatini types. The Authors include the Monti Reatini shrublands withV. myrtillusandJuniperus nanain thePino-Junipereteaclass and secondary vegetation forms dynamically linked to them in two newPoo violaceae-Nardetumsubassociations:Poo violaceae-Nardetum brachypodietosum rupestrisandPoo violaceae-Nardetum caricetosum kitaibelianae.

ISSN:0017-0070    

DOI:10.1080/11263509009428147

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The excision of the root accelerates greatly the formation of adventitious roots in the hypocotyl of etiolated radish seedlings, but if the seedlings develop in CAP 1×10−4M, no adventitious root are induced after cutting. IAA either alone or associated with CAP, significantly increases the number of primordia in normal hypocotyls if given at the moment of cutting, while it has not stimulatory effect on the hypocotyls of seedlings grown in CAP. IAA has significant effect on both elongation and tickening of hypocotyl segments prepared from seedlings grown in CAP, and this could indicate a specific action of the inhibitor either on a particular process or on particular cells.

ISSN:0017-0070    

DOI:10.1080/11263509009428148

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The anther and ovule development ofTipuana tipuis described. Some embryological aspects previously not reported for the family have been pointed out,i.e. the Basic type of anther wall development; the constant occurrence of several megasporo-cytes undergoing meiosis, the concurrent development of more than one megaspore and finally the coexistence of three or four mature gametophytes in the same ovule.

ISSN:0017-0070    

DOI:10.1080/11263509009428149

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Preliminary account of the microfungi colonizing Pistaca lentiscus L. litter- A preliminary account of the microfungi colonizingPistacia lentiscusL. leaf litter in five small islands of South Sardinia is carried out. Two species,Beltrania rhombicaPenzig andEndophragmiella boewei(Crane) Hughes are present in almost all the samples investigated. A very low index in richness of species seems to be characteristic of this particular area.

ISSN:0017-0070    

DOI:10.1080/11263509009428150

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Dehesa (open savanna-like woodland) is a Mediterranean ecosystem covering some two million hectares in the central, western and southeast parts of the Iberian Peninsula. Its importance as an ecosystem is seen from the perspective of food and energy production, scientific study and cultural traditions (Balcellset al., 1982 a, b; Humbert, 1980; Montoya, 1983; Ruiz, 1986; Vacheret al., 1985).

ISSN:0017-0070    

DOI:10.1080/11263509009428151

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A pioneer community dominated byDittrichia viscosa(L.) Greuter in a Mediterranean environment in southern Italy is described from a floristic point of view. Three main aspects are defined in a ploughed area in relation to substrate and soil depth. The pioneer role ofD. viscosais discussed in relation to its occurrence limited to below-ground disturbance.

ISSN:0017-0070    

DOI:10.1080/11263509009428152

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The paper deals with some preliminary data on the characteristics of a population of Red Juniper growing on abbandoned farmlands and xeric pasture in the central Apennines. The distribution of the older specimens is random as a result of the external origin of the seeds; all other specimens are distributed in groups due to the autochthonous origin of the seeds. The inexistence of hypogeous connections between the individuals was verified, thus confirming that asexual reproduction is of little importance in the growth of the population. The description of the population by age and by sex was made using a pyramid diagram. The diagram shows the four phases of the development of the population: colonization, stabilization, propagation and regression. While the males are more numerous, the females predominate in the older age class and are characteristic of the colonization and stabilization phases of the population. In conclusion the study demonstrates how after 39 years of the development of the population (though this is now in regression), the ecological conditions have still not reached a stage where it is possible for the species which characterise the woods in the area to develope.

ISSN:0017-0070    

DOI:10.1080/11263509009428153

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A synthesis is presented of some research results on the structure and dynamics of populations with respect to the phytocoenosis structure. The first aspects to be considered are concerned with the dynamism, distribution and reproductive strategy ofAnemone nemorosa: the vegetation structure either favors or inhibits the various reproductive strategies, thereby influencing the distribution pattern of the species. The second area of the present study is the demography and quantitative structure ofCytisus sessilifoliuspopulations with respect to the problematic of secondary successions: the first results obtained open up interesting prospectives on the relationship between the vegetation dynamics and the frutescent populations structure.

ISSN:0017-0070    

DOI:10.1080/11263509009428154

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor