摘要:

A new species of basidiomycete parasitizing the ascocarps ofRhytidhysterium rufulumis described and namedTremella rhytidhysteriiBezerra and Kimbrough sp.nov. The mycelial interaction between two species is studied with both light and electron microscopy. The cytological development of basidia and basidiospores is also described. Ultrastructural aspects of theCryptococcusimperfect state are described and compared with other described species.

ISSN:0008-4026    

DOI:10.1139/b78-366

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The incidence of internal fungal infections has been scored in coniferous needles from 19 hosts sampled in over 200 sites dispersed throughout western Oregon and southern Washington.Abies grandis, A. magnifica, Picea sitchensis, Pseudotsuga menziesii, andSequoia sempervirenshave proved congenial hosts for needle blade endophytes; petiole fungi are common in all species ofPiceaandTsugasampled. An undescribed taxon in the Hemiphacidiaceae,Chloroscyphaspp.,Cryptoclinespp.,Leptostromaspp.,Naemacyclusspp.,Phomopsisspp.,Phyllostictasp., and several unidentified Coelomycetes withPhoma-like spores were the dominant fungal taxa in the coniferous hosts sampled. The observed patterns of species dominance and diversity suggest that the true population of endophytes has been inadequately sampled in the present study and that an order of magnitude more intensive sampling might be required for real patterns of dominance and diversity to emerge. Many endophytes are restricted to a single coniferous host or to a restricted group of hosts. When similarity coefficients between coniferous species are computed on the basis of their internal needle microfloras, the resultant taxonomic groupings appear similar to those derived from consideration of conventional morphological criteria. Comparison of endophyte incidence with host distribution patterns forPseudotsuga menziesiireveals that infection rates decrease at high elevations and dry sites.

ISSN:0008-4026    

DOI:10.1139/b78-367

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The vegetation, selected characteristics of shallow groundwater, and depth to water were examined in five fens in northern Lower Michigan. The field layer was the dominant stratum in all five fens and contained a total of 85 vascular species with a mean density of 30 vascular species per stand.Carex lasiocarpawas the most prevalent dominant plant and attained a frequency–presence index (FPI) of 8000 of a possible 10 000 and a mean importance value of 33 of a possible 200. Other common dominants in decreasing order ofFPIwereCarex aquatilis(6640),Myrica gale(4636), andAndromeda glaucophylla(2000). Common subordinates wereHypericum virginicum(2639),Muhlenbergia glomerata(2466), andCampanula aparinoides(1400). The vegetation was relatively homogeneous as indicated by a homogeneity index of 58%.The shallow groundwaters were minerotrophic with pH values ranging from 5.7 to 7.0 and calcium concentrations of 11.0 to 75.0 mg/ℓ. Four of the fens were on floating mats and had relatively stable water levels while the fifth was on a grounded mat and was subject to substantial water level fluctuation.Three previously described alkaline lake-edge kettle-hole 'bog' communities were found to be similar to the fens in species composition and water chemistr

ISSN:0008-4026    

DOI:10.1139/b78-368

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Pertica dalhousiin.sp. is described from the late Lower or early Middle Devonian of New Brunswick. The plant is known from a central axis with spirally arranged, mostly dichotomous lateral branches. Some lateral branches terminate in erect clusters of 32–128 fusiform sporangia. Spores are circular, trilete, with a detachable outer sculptured layer, and resemble the dispersed spore genusApiculiretusisporaStreel. A trimerophyte from Gaspé is described and provisionally designated as cf.Perticasp.; the specimens are too incompletely preserved to be assigned to any established species, but they add further information about morphologic variation in the genusPertica.With the addition of new plant types referable to the trimerophytes, distinctions between genera and species are becoming less readily apparent, supporting the suggestion that the trimerophytes are a group of closely related plants in which considerable evolution was occurring in late Lower and Middle Devonian times. Additionally, these plants appear to represent an early stage in the differentiation of a distinct main axis – lateral branch type of organizaiton that probably led to the later evolution of megaphyllous leaves.

ISSN:0008-4026    

DOI:10.1139/b78-369

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Morphological, developmental, and cytochemical examinations were made with light and electron microscopy on the apical apparatuses ofMorchella esculenta, Helvella crispa, andRhizina undulata, all species with large, stipitate apothecia. Ascus tips inR. undulatawere markedly thinner walled than the rest of the ascus, while those inM. esculentaandH. crispawere slightly thinner than the rest of the ascus wall. Lipid bodies were detected in developing asci ofH. crispaandM. esculenta. Their unique occurrence in asci of members of the Morchellaceae and Helvellaceae may have taxonomic significance. With the electron microscope, opercula were distinguished cytochemically in all three species. InH. crispaandM. esculentadehiscent zones were found to be restricted in the inner layer of the ascal wall. Characters of the apical apparatuses ofH. crispaandM. esculentasuggest greater taxonomic relatedness between these species than with any other operculate group. The apical apparatus ofR. undulatadiffered notably from the other species.The present series of studies has demonstrated distinct variability of the operculate ascus and its apical apparatus in morphology, cytochemistry, and development. Several major forms of the apical structures were observed. These examinations support the chemotaxonomic and cytological investigations on representatives of the Pezizales made previously by Arpin and Berthet. Outside of the Thelebolaceae, members of the Pezizales are chiefly characterized by the operculate dehiscence of their asci. Members of the Thelebolaceae eject their spores through a variety of dehiscent mechanisms. Present examinations of those representatives of the Thelebolaceae with functionally operculate apparatuses, i.e.,LasiobolusandCoprotus, support their transferrance to the Pyronemaceae. Taxa which form nonoperative opercula, i.e.,AscozonusandTrichobolus, also show closer affinities with the Pyronemaceae than with the nonoperculate representatives of the Thelebolaceae. The nonoperculate members of the Thelebolaceae apparently do not belong in the operculate Discomycetes. The operculate ascus wall is structurally compared with the pored and bitunicate ascus walls. The terms 'bitunicate' and 'unitunicate' are redefined.

ISSN:0008-4026    

DOI:10.1139/b78-370

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

An Antarctic specimen chiefily consisting of the osmundine root mat and including branched stems of a fern, assignable to a new speciesOsmundacaulis beardmorensis, is described and illustrated. Delicate tissues are generally not preserved and no separate petioles can be recognized. Nevertheless, the Early Triassic age of this specimen is well established and the features that can be described seem to fit generally into an intermediate position betweenOsmundacaulis herstiiof the Argentine Late Triassic andPalaeosmundaof the Late Permian from Australia. Secretory islands in petiolar areas seem to be distinctive. The species further illustrates the long established cosmopolitan distribution of members of the Osmundaceae.

ISSN:0008-4026    

DOI:10.1139/b78-371

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The recent discovery of numerous permineralized frond segments in Upper Pennsylvanian sediments provides an opportunity to describe a new genus of the Sermayaceae and further enhance our knowledge of Paleozoic filicaleans. Specimens ofDoneggia compluragen. et sp. nov. consist of up to three orders of biseriately branched frond segments with abaxial curvature of the vascular strand in proximal pinnae and large sori of superficially borne sporangia on laminar pinnules. Sori occur on pinnule lobes below vascular bundles and consist of about 25–35 sporangia. Individual sporangia are oblong, 0.6 mm long and 0.45 mm in maximum diameter, and are attached by a short stalk. As inSermaya, the horizontal–oblique annulus consists of two rows of interfingering cells and is interrupted at one side by a narrow band of longitudinally oriented, thin-walled cells that presumably acts as a zone of dehiscence. Also, as inSermaya, the vascular bundles have adaxially disposed protoxylem strands and crowded bordered pits on walls of the metaxylem tracheids. Spores are radial, trilete, triangular in polar view, and measure 45–63 μm in diameter. Material of this type helps demonstrate that some taxa that are currently assigned to the Coenopteridales actually represent vegetative organs of Paleozoic filicaleans.

ISSN:0008-4026    

DOI:10.1139/b78-372

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The Carboniferous pteridosperm pollen typeMonoletesis described from reproductive organs of differing preservational mode and stratigraphie occurrence. The sporoderm is constructed of two zones: an inner thin lamellated nexine and a thicker alveolate sexine. The ultrastructure of the sporoderm in the area of the proximal suture suggests that germination may have taken place from that region. Distal surface grooves are a consistent feature of the grains examined although grain ontogeny, preservation, and tapetal products may mask their presence. Features of sporoderm infrastructure suggest thatMonoletespollen grains may represent a type transitional between wind and insect pollination.

ISSN:0008-4026    

DOI:10.1139/b78-373

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Anew taxodiaceous ovulate cone,Austrosequoia wintonensisgen. et sp. nov., is described from the area of Winton, Queensland. Australia. The material is believed to come from the Upper Cretaceous but may be younger. The cones have 29–49 cone scales arranged helically around the axis. Each scale has four to seven ovules arranged in a single row. Reproductive shoot leaves are rhomboidal with an incurved apex and a distinct keel. Comparison with extant taxodiaceous genera indicate a strong similarity toSequoia sempervirens(D.Don) Endl. andSequoiadendron giganteum(Lindl.) Buchholz. Only limited similarities are observed with species of the Australian endemicAthrotaxis. The deposit also contains conifer pollen cones, ferns, and angiosperm remains which are yet to be described.

ISSN:0008-4026    

DOI:10.1139/b78-374

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Pekinopteris auriculata, from the Upper Triassic of North Carolina, has once-pinnate leaves attached in crowded fashion on a branched, apparently fleshy rhizome. Some of the leaves may have exceeded 40 cm in length and bear elongated pinnules, each with a main vein and sparse, ascending, anastomosing laterals. Portions of the rhizome bore roots, while other portions lacked them. One possible interpretation is that the proximal part of the rhizome may have been attached to some kind of substrate, with a distal portion that was partially erect or extending away from the substrate. Evidence seems to point toward an affinity ofPekinopteriswith the ferns rather than with seed plants.Pekinopteris, along with many other ferns, probably contributed to the 'ground cover' of Upper Triassic landscapes.

ISSN:0008-4026    

DOI:10.1139/b78-375

出版商:NRC Research Press    

年代:1978

数据来源: NRC