摘要:

This paper describes a method for optimizing grid scale when presence–absence records are to be used in a numerical biogeographic study. Optimality is held to reside at that size of grid square which maximizes the number of matches in presence–absence comparisons over all pairwise species comparisons. The paper is illustrated with an example from Turkish poppies (Papaver).

ISSN:0008-4026    

DOI:10.1139/b75-176

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

New analyses of pine, spruce, fir, larch, and red maple tissue from the Tantramar Copper Swamp, New Brunswick, fail to confirm the exceptional high copper contents previously reported from this location. Foliar contents did not differ from those of nearby controls, and contents in 1st- and 2nd-year twigs were only two to three times higher than in controls, still within the normal range of values in the literature. In contrast, bulk samples of fine roots from the swamp contained over 2000 ppm Cu. Parallel comparisons of hemlock growing on Cu-enriched mineral soils from Long Island, New York, revealed that root Cu increased linearly with extractable soil content, whereas foliar Cu was unaffected. Thus, it appears that roots and twigs may be better indices of plant Cu status than foliage.

ISSN:0008-4026    

DOI:10.1139/b75-177

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Initial pH and sucrose concentration of the medium markedly affected sporulation and conidial characteristics in fourBipolarisspecies.Bipolaris sorokinianaandB.zeicolasporulated well at all pH levels;B.setariaeandB.maydisproduced relatively fewer conidia. Most isolates ofB.sorokinianasporulated well at all sucrose concentrations; sporulation byB.zeicolaandB.maydiswas less abundant, particularly at high sucrose levels. Only one of six isolates ofB.setariaeproduced conidia at sucrose concentrations higher than 5 g/litre.In all four species conidium length and number of septa per conidium significantly decreased as the pH of the medium was increased, although some isolates ofB.sorokinianashowed great variability. Conidium width was less markedly affected. Generally, inB.sorokinianaconidium length and number of septa decreased as the sucrose concentration was increased from 1 g/litre to 30 g/litre. InB.zeicola, conidia of maximum length and number of septa were produced on sucrose concentrations of 5 g/litre. Conidial characteristics ofB.maydiswere less markedly affected by increases in sucrose concentration.

ISSN:0008-4026    

DOI:10.1139/b75-178

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Vascular plant species diversity in the ravines of the southern Finger Lakes followed the ravine-side gradient and vegetation characteristics described by Lewin (1974). Bottom and lower-slope mesophytic communities were very rich in species, middle-to-upper hemlock stands were very poor in species, while the upper oak stands were again somewhat richer. Dominance followed an inverse pattern, being lowest in the low, mesophytic stands and high in the hemlock stands. The amount of hemlock in the canopy appeared to have an effect on diversity.

ISSN:0008-4026    

DOI:10.1139/b75-179

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

During controlled hardening of alfalfa, the lipid phosphorus content of the roots increased in the hardy variety Rambler while it decreased in the frost-sensitive variety Caliverde. Incorporation of33Piinto the lipids decreased in both varieties during hardening but less in Rambler than in Caliverde. The proportion of the lipid radioactivity incorporated in phosphatidylcholine increased only in this phospholipid in both varieties. This increase was greater in Rambler than in Caliverde. The varietal differences in lipid phosphorus levels observed in hardened alfalfa seem therefore to be mainly the result of different rates of phospholipid degradation during hardening. However, the significant varietal difference in incorporation of33Piinto lipids during hardening suggests that the higherde novosynthesis of phospholipids, mainly phosphatidylcholine, in the hardy variety also plays a role in the hardening process.

ISSN:0008-4026    

DOI:10.1139/b75-180

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Ten morphological characters have been examined from 455 collections ofB.papyriferaMarsh., 95 collections ofB.cordifoliaRegel, 56 collections ofB.populifoliaMarsh., 64 collections ofB.neoalaskanaSarg., and 70 collections ofB. ×caeruleaBlanch. taken from their ranges within Canada. The somatic chromosome numbers were found to be 70, 84, and more rarely 56 (possibly hybrids) forB.papyrifera, 28 and more rarely 42 and 56 forB.cordifolia, and 28 forB.populifolia,B.neoalaskana, andB. ×caerulea. Observations on juvenile characters and growth rates indicated that it is possible to distinguish these taxa at an early age. Comparison of the characters on an interprovincial basis within species revealed no significant differences inB.populifolia(P < .05). However, significant differences were observed in one or more characters from the other species. No significant differences were found between species whenB.papyriferawas either sympatric or allopatric withB.cordifoliaandB.populifolia; whenB.cordifoliawas sympatric butB.populifoliawas not; and whenB.populifoliawas sympatric butB.cordifoliawas not. A canonical analysis of the New Brunswick data incorporating the 10 characters indicated clear distinctions amongB.papyrifera,B.cordifolia, andB.populifoliaand provided further evidence thatB. ×caeruleais a hybrid ofB.populifoliaandB.cordifolia. Considerable introgression ofB.caeruleawithB.populifoliawas noted in these data.

ISSN:0008-4026    

DOI:10.1139/b75-181

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Twelve North American species of the sectionCordataeof the genusSalix(willows) were studied to clarify their taxonomy. The sectionsAdenophyllae(Commutatae) andWolfianaeare included here in sectionCordatae. Characteristics of the epidermal cells and pollen grains were of no taxonomic value. Chromosome counts were obtained for 6 of the 12 species. One other species had been counted earlier. There are three diploid species, two tetraploids, and a hexaploid. One other species (?) has both diploid and tetraploid populations. Flavonoid chemistry of the leaves was the most important and constant characteristic. Each species has a consistent combination of compounds different from those of all other species of the section. Cytology, chemistry, morphology, and distribution were well correlated. Keys to pistillate material, synonymy, descriptions, distribution maps, and representative specimens are included. Three new species are described and one varietal transfer is made.

ISSN:0008-4026    

DOI:10.1139/b75-182

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The summation of air temperatures above 2.2 °C for a 6-week period before flowering explained most of the annual variation in the flowering date of dogwood (Cornus floridaL.) at Wauseon, Ohio. The same total was a fairly accurate predictor of flowering date throughout dogwood's native range, which suggests that geographical variation in flowering time is environmentally rather than genetically controlled. Results of the current study are inconclusive concerning spatial variation in the probability of frost on the date of flowering.

ISSN:0008-4026    

DOI:10.1139/b75-183

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Results from studies of carbon dioxide assimilation in lichens cannot be tested independently against growth studies. To compensate for this, rapid, more rigorously controlled experimental systems must be used to sample a much wider range of environmental conditions.Methods in popular use are found to be inadequate in these respects.A new simple system is described which permits the response of net photosynthesis in lichens to be examined more efficiently than was previously possible.

ISSN:0008-4026    

DOI:10.1139/b75-184

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Growth and extracellular polysaccharide (EP) production by cotyledon suspension cultures of bush bean were compared in coconut-milk (CM) medium and synthetic medium. EP was produced at all stages of the culture cycle investigated. The same neutral sugars were present in the EP recovered from both media and the composition showed some changes during the culture cycle. Factors in coconut milk had relatively little effect on the neutral sugar composition of the EP.

ISSN:0008-4026    

DOI:10.1139/b75-185

出版商:NRC Research Press    

年代:1975

数据来源: NRC