摘要:

As part of a study of the forest vegetation of the Island of Montreal, 10 stands of deciduous hardwoods of Cap Saint-Jacques were sampled with the quarter method. Indirect ordinations indicate that the floristic organization of these urban forests is mainly due to surficial deposits and moisture regime in addition to the types and the intensity of disturbances.

ISSN:0008-4026    

DOI:10.1139/b79-143

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Six ectomycorrhizal fungi commonly associated with Douglas-fir were testedin vitrofor acid phosphatase activity by measuring the amount ofp-nitrophenyl phosphate converted top-nitrophenol and by examining their production of isoenzymes detectable by starch gel electrophoresis. Both test methods showed acid phosphatase activity to be highest inHebeloma crustuliniforme, followed by progressively lower activity inLaccaria laccata, Amanita muscaria, andThelephora terrestris. Rhizopogon vinicolorandPiloderma bicolorshowed low activity. We discuss the significance of these fungi in the utilization of complex phosphates by tree roots.

ISSN:0008-4026    

DOI:10.1139/b79-144

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Satureja gilliesiiis a small shrub, representative of the Chilean mediterranean vegetation found on arid slopes and on partially degraded soils. It has two types of branches: dolichoblasts with winter leaves and brachyblasts with smaller spring leaves. The leaves are mesophytic and no stomatal control is detectable. Dolichoblast leaves are shed at the beginning of drought but the brachyblast leaves that have become dry and brownish remain attached to the plant. Even while the plant undergoes a severe water stress, these leaves survive throughout the drought period in a state of marked dehydration. After the first winter rain, they become turgid and regain a green color. Thus,S. gilliesiishows a poikilohydric behavior such as that described for some angiosperms.

ISSN:0008-4026    

DOI:10.1139/b79-145

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

An antiviral agent, active against spherical and tubular viruses in hypersensitive and systemic hosts, has been isolated from the roots ofBoerhaavia diffusa. Partial purification of inhibitor by organic solvents, Sephadex gel, and protein precipitants has been achieved. Preliminary analysis indicates that the inhibitor may be a glycoprotein with a molecular weight of 16 000–20 000 daltons.

ISSN:0008-4026    

DOI:10.1139/b79-146

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Pithoascus intermediuswas isolated for the first time from seeds of lowbush blueberry,Vaccinium angustifolium. The low rate of germination of infected seeds suggested that the fungus may have been pathogenic on the host.

ISSN:0008-4026    

DOI:10.1139/b79-147

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The trichomes of slipper spurge (Pedilanthus tithymaloidesPoit.) are uniseriate, curved, and branched or unbranched. The trichome originates by an enlargement of a single protodermal initial, which elongates and gradually becomes curved, septate, and branched. Cytoplasm is present only during its early developmental stages. Later its cytoplasm and nucleus undergo necrosis and its walls become thickened. The structural changes occur during the bilumenation of the basal cell. The distal part above the bilumenated basal cell of the trichome is finally shed and only the thick-walled basal cell remains.

ISSN:0008-4026    

DOI:10.1139/b79-148

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Cultures of 28 ectomycorrhizal fungi were tested in pure culture syntheses for mycorrhiza formation with red alder. Only 4 of the 28 fungi tested formed characteristic ectomycorrhizae:Alpova diplophloeus, Paxillus involutus, Aslraeus pteridis, andScleroderma hypogaeum. These mycorrhizae are briefly described, and the specialization of alder mycorrhizae is discussed.

ISSN:0008-4026    

DOI:10.1139/b79-149

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

When the buds on the rhizome ofAgropyron repenswere released from apical dominance either by increasing the nitrogen supply or by raising the humidity around the rhizome, their uptake of14C-labelled assimilates from the parent shoot was significantly increased. While this effect was produced by each treatment when applied separately, the uptake of14C by the buds was more than twice as great when both treatments were combined. The14C level in the rhizome was also increased, this effect being greater and more consistent in response to the change in humidity than to the increased nitrogen supply. In the controls, uptake of the labelled assimilates was greatest by the bud at the apical node and decreased basipetally along the rhizome. This pattern was not correlated with bud size and probably resulted from a basipetal gradient of declining metabolic activity. Increasing the humidity around the rhizome altered this pattern, preferentially promoting the uptake of the label by the bud at the subapical node. To account for the stimulation of bud growth by high humidity when nitrogen was apparently the limiting factor, it is postulated that the increase in water potential of the bud may accelerate protein synthesis, thereby enhancing the bud's capacity to compete for the limiting nitrogen supply.

ISSN:0008-4026    

DOI:10.1139/b79-150

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Six moss species were grown in two growth chambers with similar environmental conditions except for their ç ratios (E660:E730). One chamber simulated a sunlit situation the other a subcanopy shade situation. Different growth responses were observed for several species in the two chambers, which were often in the opposite direction to observations made on vascular plants. The ç ratio may be an important factor in regulating the distribution of mosses in the natural environment.

ISSN:0008-4026    

DOI:10.1139/b79-151

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Anatomy of the achene is studied in four varieties ofCannabis sativa(sativa, spontanea, indica, andkafiristanica) at different stages of its development from the ovary. The nucellus undergoes extensive curvature soon after fertilization so that the campylotropous ovule assumes an ana-amphitropous form. The endosperm is nuclear and shows a permanently coenocytic haustorial caecum. The embryo, when mature, is curved and dicotyledonous and occupies most of the space in the seed. The cotyledons enclose a set of well formed plumular leaves. Stored food is present in cells of both the radicle and the cotyledons and also in one to several layers (depending on position) of the endosperm. The seed coat has little or no protective role in the propagule but chloroplasts are formed in it soon after the globular embryo stage. In the pericarp, it is the endocarp layer that undergoes the most striking transformation; the cells show gross enlargement and extensive cell wall modification and thickening. The layer which lies immediately above the endocarp as well as the epicarp also show wall thickening but no significant increase in cell size. A careful comparison at identical stages among the four varieties reveals no significant difference is achene development.

ISSN:0008-4026    

DOI:10.1139/b79-152

出版商:NRC Research Press    

年代:1979

数据来源: NRC