摘要:

Anastrophyllum assimile(Mitt.) Steph. andMarsupella revoluta(Nees) Lindb. are reported from the Keele Peak area, central-eastern Yukon Territory, Canada, andM. revolutais also reported from Devon Island, Northwest Territories, Canada. These new localities extend a pattern of disjunct occurrences throughout the known range of both species, which further support the hypothesis of their relictual status. However, collections ofA. assimilefrom coastal British Columbia and the Alexander Archipelago, Alaska, are indicative of strong oceanic affinities of North American populations of this species. Also, the arctic and alpine localities at which eitherA. assimileorM. revolutamight be expected to occur in the interior of Alaska and the Yukon are limited in number as both species invariably occur in association with siliceous substrates.

ISSN:0008-4026    

DOI:10.1139/b77-282

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The mycelium ofTaphrina deformans(Berk) Tul. stands beneath the cuticule in the layer of pectic substance which spreads over the cellulosic wall of epidermic cells.It also runs within the mesophyll in the amorphous substance of pectic nature which is localized along the ridges of cells and is probably the initium of the middle lamella. This structure often remains incomplete in parasitized leaves.Hyphae do not seem to attack cellulosic walls, cuticule, or pectic substance. They seem to progress chiefly by physical means.

ISSN:0008-4026    

DOI:10.1139/b77-283

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Taraxacum officinaleplants representative of three altitudinally diverse populations were grown under uniform conditions. Temperature responses of net photosynthesis, photorespiration, and transpiration were obtained from four plants of each population over the range of 10 to 40 °C at saturating irradiances(1000 μE ∙ m−2∙ s−1). Dark respiration rates were obtained from the same plants over the range of 10 to 30 °C. All plants exhibited similar gas exchange responses to temperature regardless of population origin. Maximum rates of net photosynthesis occurred near 20 °C in all plants and averaged 20.8 mg CO2∙ dm−2∙ h−1(mean of 12 plants). Dark respiration and photorespiration rates increased nearly linearly with temperature in all plants. These results are in contrast with previous studies of the same populations in which differences in Hill activity and succinate dehydrogenase activity were reported. However, the photosynthetic patterns and lack of genetic differentiation of photosynthesis are similar to the results obtained for another weedy species,Verbascum thapsus, along the same altitudinal t

ISSN:0008-4026    

DOI:10.1139/b77-284

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The chromosome numbers for 137 populations of 24 species are reported. First reports ofn = 5 are given forChrysopsis decumbens, C. floridana, C. hyssopifolia, C. lanuginosa. C. latisquamea, andC. scabrellaand 2n = 18 forC. cruiseana. The occurrence of the diploid 2n = 8 forC. marianais also reported for the first time. The base number ofHeterothecaisx = 9, while the base numbers ofChrysopsisarex = 4 and 5 and.x2 = 9. A realignment of sections included in the two distinct genera is proposed.

ISSN:0008-4026    

DOI:10.1139/b77-285

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A new species ofPsaroniusis described from permineralized monocyclic stems with distichous leaf scars. Diameters for the steles are 3.5–4.4 cm, up to 6.5 cm for the stem, and 8 cm for the trunk which includes inner and outer roots; the longest of 11 specimens is 32 cm. These specimens from the lower Pennsylvanian of western Illinois are the oldest known histologically preserved stems and roots for the genus.Psaronius simplicicaulissp.nov., with its distichous leaf arrangement, is very similar to Mississippian – early PennsylvanianMegaphytonspecimens, indicating that the earliest known marattialean tree ferns were smaller in diameter than their late Pennsylvanian relatives and probably monocyclic with distichous fronds. The middle Pennsylvanian increase in the distribution and abundance ofPsaroniusgenerally coincides with increased size, polycyclic stelar anatomy, and polystichy.

ISSN:0008-4026    

DOI:10.1139/b77-286

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A second distinct chlorophylla– protein complex has been resolved in extracts of maize mesophyll chloroplasts. Resolution was accomplished through modified incubation and electrophoresis and through the use of a mutant deficient of chlorophyllb. This complex, complex IV, has an electrophoretic mobility similar to that of the light-harvesting chlorophylla/b– protein and chlorophyllais its major pigment component. Carotenoids are probably also present in this complex. Evidence to date indicates a correlation between the presence of complex IV and photosystem II.

ISSN:0008-4026    

DOI:10.1139/b77-287

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Incubation of cell suspensions of sycamore (Acer pseudoplatanus) with β-indoyl-3-acetic acid (IAA) first led to the formation of IAA-glycosides, then to that of IAA-aspartate. Great differences are observed between the kinetics of IAA transformed by two distinct strains: one, auxin dependent (S), the other, auxin independent (MB). Other degradation products are only found in the culture medium. The localization of IAA-degrading systems in the cell wall is postulated. The auxin requirement of the S strain is discussed.

ISSN:0008-4026    

DOI:10.1139/b77-288

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Monochaetiella hyparrheniaeCastell. the type ofMonochaetiellaCastell. is redescribed and illustrated.Monochaetiella themedaeKandasw. & Sundar. andM. cymbopogonisPunith. & Sarwar are separated intoMonochaetiellopsisgen.nov. by differences in conidial morphology, conidiogenesis, and acervulus structure. The generic relationships ofMonochaetiellaandMonochaetiellopsisare discussed.

ISSN:0008-4026    

DOI:10.1139/b77-289

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Ascospores ofPyronema domesticumcontain three distinct spore wall layers. The liberation of ascospores presumably commences immediately after the three spore wall layers are formed. This is evidenced by the fact that vesiculation of the investing membrane was observed at the time when three wall layers could be distinguished. Vesiculation continues until the total disappearance of the perispore. Concurrently the epiplasm of the ascus degenerates and converts into a large vacuole within the ascus. Spores are violently ejected through the apical pore that is surrounded by a weakened apical ring. Presumably eight ascospores are discharged at the same time but do not adhere as a single unit. The operculum is generally not hinged to the main body of the ascus and an ascus without ascospores degenerates.

ISSN:0008-4026    

DOI:10.1139/b77-290

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

For 21 study sites in the Acadia Forest Experiment Station, near Fredericton, New Brunswick, 34 commonly occurring understory species were studied to determine the depth of underground plant organs capable of growing shoots. Depth of these plant parts tended to be species specific. These depth data, together with a knowledge of the sprouting ability of the underground organs, were used to postulate which species would survive fires of varying intensities. Most species found in the litter layer or in the F and H layer of the forested study sites would be susceptible to fires of low intensity.Rubus canadensis, Kalmia angnstifolia, Vaccinium myrtilloides, Pteridium aquilinum, andViburnum cassinoideswould probably survive severe fires because the subterranean plant organs capable of reproduction were found in the mineral soil. In the bog study sites,Vaccinium oxycoccos, Andromeda glaucopliylla, Kalmia angustifolia, Chamaedaphne calyculata, Ledum groenlandicum, andRhododendron canadensewould likely survive severe fires because the plant organs capable of vegetative reproduction were found 25 cm below the surface of the bog.

ISSN:0008-4026    

DOI:10.1139/b77-291

出版商:NRC Research Press    

年代:1977

数据来源: NRC