摘要:

An exhaustive survey of snow patches, along an altitudinal gradient situated in an area of about 10 km2along the Hudson Bay highlands, underlines the role of altitude, exposition, and topography in maintaining these habitats. The principal component analysis from a stratified sampling of the snow patches in the three cuesta lithological zones (arkose, dolomite, and basalt) stresses the effect of the snow melt gradient on species distribution within a snow patch. The ordination of abiotic variables performed on the ordination frame of snow patches shows that lithology and substratum are the principal factors responsible for the vegetation characteristics, allowing the determination of two main types of snow patches in the arkose and dolomite zones and three types in the basalt zone.

ISSN:0008-4026    

DOI:10.1139/b86-207

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

A study of herbarium material ofElodeaspp. andEgeria densawas undertaken to document status in Canada and to evaluate existing methods of identification. Except inElodea longivaginata, nonflowering plants are 2 – 3 times more common than flowering plants and females are more common than males. Leaf width partially separatesE. canadensisandE. nuttalliimales but not females. The ratio of pistillate sepal length versus leaf width separates femaleE. canadensisfrom femaleE. nuttallii, but intermediates exist. Nonflowering plants with leaf widths of 1.8 – 2.2 mm are treated as unknowns. Bifid styles are characteristic ofE. longivaginata. Keys, descriptions, and drawings based on Canadian material are provided. The introducedEgeria densaoccurs rarely in southwestern British Columbia.Elodea longivaginataandE. nuttalliiare both rare native species, the former occurring in southern Alberta and southern Saskatchewan and the latter occurring in southern Ontario and southern Québec, Nova Scotia, southern Manitoba, and southern British Columbia.Elodea canadensisis a widespread native species occurring throughout southern Canada.

ISSN:0008-4026    

DOI:10.1139/b86-208

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Changes in photosynthetic carbon fixation processes were comparatively studied in soybean leaves and pods harvested at different growth stages. Newly fully expanded leaves exhibited both the highest14CO2assimilation rate and the maximum ribulose bisphosphate carboxylase levels. Amino acids biosynthesis was more important in young tissues and this result agreed with the evolution of nitrate reductase activities. The radiocarbon distribution in glycine and serine suggested that photorespiratory metabolism increases with leaf age; the activity of glycolate oxidase was found to be significantly lower in younger leaves than in mature ones. Net photosynthesis, chlorophyll content, and ribulose bisphosphate carboxylase activity were low in isolated pods compared to leaves. However, the study of photosynthate translocations within the pod revealed that the pod wall could contribute to the carbon nutrition of the seeds. Soluble compounds labelled after14CO2incorporation and glycolate oxidase activity measurement indicated that organic acids biosynthesis and photorespiratory metabolism are relatively higher in pods than in leaves.

ISSN:0008-4026    

DOI:10.1139/b86-209

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

This is a floristic treatment of benthic marine red algae (Rhodophyta) in the order Rhodymeniales which occur in British Columbia and northern Washington. The following 12 species in 9 genera are recorded and illustrated:Botryocladia pseudodichotoma(Farlow) Kylin,Fauchea fryeanaSetchell,Fauchea laciniataJ. G. Agardh,Faucheocolax attenuataSetchell,Fryeella gardneri(Setchell) Kylin,Gastroclonium subarticulatum(Turner) Kützing,Lomentaria hakodatensisYendo,Minium parvumMoe,Rhodymenia californicaKylin,Rhodymenia pacificaKylin,Rhodymenia pertusa(Postels et Ruprecht) J. Agardh, andRhodymeniocolax botryoideaSetchell.Rhodymenia stipitataKylin is treated as a taxonomic synonym ofRhodymenia pertusa. Previous reports ofCoeloseira parvaHollenberg from British Columbia andLeptofauchea auricularisDawson andLeptofauchea pacificaDawson from northern Washington were based on misidentifications or could not be confirmed. Also provided is a historical background of the Rhodymeniales. Keys to and descriptions of local taxa (at the ordinal, familial, and generic levels), as well as information on synonyms, location of type specimens, type localities, and what is known about the life histories, distribution, seasonality, and habitats of all local taxa, are provided. Rhodymenialean species occurring in British Columbia and northern Washington which are also reported in the California flora are listed, as are those which are restricted to one or the other flora. References are given and representative specimens cited that document our concepts of the taxa and their morphological variability, seasonality, and geographical distributions.

ISSN:0008-4026    

DOI:10.1139/b86-210

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Lanspora, a new marine pyrenomycete from driftwood collected in the Seychelles is described withL. coronataas the type species. The genus is compared with the marine generaCorollospora,Eiona,Halosphaeriopsis,Ocostaspora, andRemispora.

ISSN:0008-4026    

DOI:10.1139/b86-211

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Acetone–toluene extracts ofCladonia cristatellainhibited the growth of fungi known to form ectomycorrhizal associations with trees commonly found on bituminous strip-mine spoils in western Pennsylvania. Growth ofPisolithus tinctoriusandSuillus luteuswas completely inhibited byC. cristatellaextracts over a 30-d bioassay period.Thelephora terrestriswas dead after 17 d. The growth ofCenococcum graniformewas unaffected by lichen extracts. D-Usnic acid, a major secondary compound of theC. cristatellaextract, was found to inhibit the growth ofP. tinctorius. This inhibition, however, did not account for the total inhibition ofP. tinctoriusdemonstrated by the gross acetone–toluene extract. Other secondary compounds, and potential allelopathic substances, present in the extract were barbatic acid, didymic acid, condidymic acid, subdidymic acid, fumarprotocetraric acid, squamatic acid, and rhodocladonic acid.

ISSN:0008-4026    

DOI:10.1139/b86-212

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Questieriella quercinan. sp. is illustrated and described on leaves ofQuercussp. from Costa Rica. Sydow's Fungi exotici exsiccati 857 subSchiffnerula compositarumis assigned toS. oyedaeae.

ISSN:0008-4026    

DOI:10.1139/b86-213

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Apical (elongating) and basal (nonelongating) segments of bean hypocotyls were labelled with [4-3H] proline andin vivoprolyl-4-hydroxylase activity, and peptidyl proline synthesis and hydroxylation were determined. Prolyl-4-hydroxylase activity was negligible in newly excised segments. However, if segments were aerated before labelling, hydroxylase activity, uptake, and incorporation of [4-3H]proline were all significantly increased.3H loss was negligible in the presence of α, α′-dipyridyl or when sections were labelled with [2,3-3H]proline. In basal sections aerated for 24 h, prolyl-4-hydroxylase activity and the proportion of peptidyl proline hydroxylated were twice that observed in apical sections. The data indicated that peptidyl proline biosynthesis was similar in nonelongating and elongating segments. When apical sections were aerated in solutions of NaCl, mannitol, or benzimidazole, at concentrations inhibitory to elongation, there was an increased release of3H from [4-3H]proline. However, a similar increase in3H release occurred in the [2,3-3H]proline-labelled controls. The results suggest that neither increased prolyl-4-hydroxylase activity or peptidyl proline biosynthesis are an obligatory requirement for cessation of growth in excised bean hypocotyls.

ISSN:0008-4026    

DOI:10.1139/b86-214

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Chara buckelliiis a euryhaline alga that provides a model for the comparative study of osmotic relations under different salinity regimes within the same species.Chara buckelliiis native to a saline lake (Waldsea Lake) in which the major ionic constituents are Mg2+andas well as Na+and Cl−(approximately 110 mMeach). Plants were cultured in artificial Waldsea water, ordinary seawater diluted to match the osmotic pressure of Waldsea water (375 mosmol/kg), and freshwater. The major osmotica in the vacuole of Waldsea-water and seawater cells are K+, Cl−, and Na+, although seawater cells have significantly more Na+than Waldsea-water cells. The vacuole of freshwater cells contains primarily K+, Cl−, and Mg2+. Turgor is regulated in a range from 323 ± 5 to 212 ± 7 mosmol/kg when the external osmotic pressure ranges from 5 (freshwater) to 567 (1.5 × Waldsea water) mosmol/kg. Waldsea-water cells regulate turgor primarily with K+and Cl−, whereas seawater cells regulate with K+, Cl−, and Na+. The possible role of Mg2+in the early stages of turgor regulation is discussed. Cytoplasmic K+concentrations are also reported and are comparable with those found in the literature for related charophyte genera. The results presented here are compared with modes of turgor and osmotic regulation in other euryhaline and freshwater algae.

ISSN:0008-4026    

DOI:10.1139/b86-215

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Bark on the scaffold limbs of 6-year-old peach (Prunus persica(L.) Batsch cv. Redhaven) trees was mechanically wounded and tissue samples for ultrastructural study were taken after 6, 8, 12, and 14 days. Examination with light and fluorescence microscopy revealed lignification of boundary zone cell walls after 6 days followed by suberization of the lignified cell walls after 8 days. Necrophylactic periderm was present by day 12 and, by day 14, three to five cells of the new phellem were observed. Examination of tissues with transmission electron microscopy revealed suberin lamellae on the inner wall of boundary zone cells. These cells contained senescing cytoplasm with fragments of undifferentiated dense material that formed a thin, discontinuous granular deposit inside the suberin layer. Suberin lamellae did not occlude plasmodesmata. Cells of the new phellem were radially compressed, heavily suberized, and lacked pits or plasmodesmata.

ISSN:0008-4026    

DOI:10.1139/b86-216

出版商:NRC Research Press    

年代:1986

数据来源: NRC