摘要:

AbstractPseudoscleropodium purum,presently found scattered throughout the world, appears to be unquestionably indigenous only to Europe. Reports of its establishment on Tristan da Cuñha are in error; examination of the labels on duplicates of the single Argentinean collection raises the possibility that it originated in Europe.P. purumis newly reported from Chile. A distribution map of the species is provided.

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.523

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.527

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.531

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe distribution and variation in size of male gametophores associated with fertile, female cushions ofLeucobryum glaucumandL. juniperoideumin two Welsh localities are described. Both dwarf and larger males were present in fruiting cushions of both species; no independent male plants were found. It is suggested that the scarcity of functional males might be a factor limiting sporophyte production in these species.

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.535

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractGrowth rates were obtained for four mosses associated with tufa deposits. Rates per annum were as follows:Cratoneuron commutatumvar.commutatum,1–4 mm;Eucladium verticillatum,2–3 mm;Gymnostomum recurvostrum,1–3;Rhynchostegium riparioides, ca30 mm. The results are discussed with reference to tufa deposition, water chemistry and water flow. A method for identifying bryophyte remains in postglacial tufa is also described.

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.543

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe physiological response ofHylocomium splendens(Hedw) Br. Eur. to incubation in distilled water and solutions of phosphate, arsenate, selenite and selenate was investigated. Potassium efflux was found useful for comparing toxicity but was unreliable for short-term studies due to an initial rapid loss of potassium within ten minutes of immersion in any solution. This potassium loss could, under noninhibitory conditions, be regained by moss shoots. Selenite prevented re-accumulation of potassium lost in the first few minutes of incubation whilst arsenate promoted potassium loss throughout incubation. Photosynthetic oxygen evolution was progressively reduced under conditions of increasing arsenic uptake. Thus, photosynthetic rates were a more sensitive measure of anion toxicity than potassium efflux.Electron microscopic observations revealed that incubation in distilled water had little effect on immature leaves ofH. splendenswhilst arsenate incubation induced loss of cytoplasmic electron density and swelling of chloroplast lamellae in immature tissue. Mature leaves, incubated in both arsenate and distilled water, showed changes in celluar morphology compared to non incubated tissue. These changes were not reflected in potassium efflux data. The results indicate that shortterm submersion is disruptive to the fine structure of moss shoots. This is discussed in terms of the design and interpretation of experiments involving toxic ions.

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.551

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractA complete mineral nutrient fertilizer solution was added to carpets ofPseudoseleropodium purumgrowing in Windsor Forest, Berkshire, to study the efficiency of nutrient capture from dilute solutions and its effect on growth. In the experiment different frequencies of application were balanced by employing different concentrations of fertilizer so that all treatment plots received the same quantities of nutrients over a six-month period. At the end of the experiment the concentrations of macronutrients (N, P, K, Mg, Ca) within the moss tissues were determined and shoot growth was assessed by the tagged shoot method.Significant luxury uptake occurred only in the case of P where shoot concentrations in fertilized plots were 50% above the control. Smaller net increases were noted for other elements, particularly Mg. Shoot N concentration was hardly affected by fertilizer application possibly due to efficient internal recycling of the element inP. purum.Levels of exchange ably held cations were not markedly increased by fertilizer addition in the field experiment but when shoots were incubated with fertilizers in the laboratory for 30 min the concentrations of exchangeable Ca and Mg rose appreciably and exchangeable K fell. These changes appear to be quickly reversed under field conditions without transfer of cations to the protoplasts. The importance of elevated cation exchange capacity in the initial sequestration of nutrient cations is, therefore, questioned. Growth stimulation due to fertilizer treatment was negligible. Maximum net uptake of P, Mg and Ca occurred when plots were watered at weekly intervals with a dilute fertilizer and least occurred where a concentrated solution was applied at less frequent intervals implying that contact time betweenP. purumand its potential nutrients is an important factor. The period elapsing between fertilizer additions may also have significance, however, due to leaching away of nutrients and the re-establishment of a natural ionic balance at the cell wall exchange sites. Levels of nutrient absorption and growth were greatest at a site where the moss remained moist longest. This result indicates that the ability ofP. purumto absorb and utilize additional nutrients is governed by general metabolic performance which is itself restricted by water supply in Windsor Forest.

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.565

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractMonoclonal cultures ofFossombronia brasiliensiswere grown with different photoperiods, temperatures and inorganic nitrogen sources. The subsequent vegetative growth and production of gametangia is described. A quantitative analysis of the numbers of antheridia and archegonia and their relative proportions is given. At 18°C,F. brasiliensiswas found to be a short-day plant, with a critical night length of between six and twelve hours, while at 10°C it exhibited quantitative SD plant properties. Plants produced more male gametangia at 18°C and more female gametangia at 10°C. Nitrogen as nitrate consistently produced more gametangia than the ammonium source.

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.581

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.593

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1987.14.3.594

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor