摘要:

Generic concepts in the Testudinaceae (Ascomycotina, Loculoascomycetes) are reviewed with particular emphasis on the sculpturing of the ascospores which has been examined by scanning electron microscopy (SEM) for the first time. A key to the nine genera accepted in the family is provided of which two are described as new:UlosporaforU. bilgramiicomb.nov. (=Zopfia bilgramiiD. Hawksw.et al.), the ascospores of which have three to six deep fissures in each cell, andZopfiofoveolaforZ. punctatacomb.nov. (=Zopfia punctataD. Hawksw. & C. Booth), with distinctly and regularly foveolate ascospores. One further new combination is made:Rechingeriella boudiericomb.nov. (=Zopfia boudieriArnaud). The positions of three additional genera referred to the family by earlier authors but which are excluded from it here are also briefly discussed.

ISSN:0008-4026    

DOI:10.1139/b79-017

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

InOchna atropurpureaDC., five to seven crescent-shaped gynoecial primordia are formed. They become continuous with each other soon after their inception and thus form a syncarpous gynoecium whose final appearance is pseudoapocarpous (ecological apocarpy). There are as many ovules as gynoecial primordia. Each ovule arises from the biseriate tunica and the corpus on the periphery of the floral apex in the axil of a gynoecial primordium. The presence of across zone (Querzone) could not be clearly demonstrated. Since the position of ovule inception is equivalent (homotopous) to that of axillary branches, we propose to term this configurationaxillary placentation. If it is agreed upon that axillary branches arise from the stem (caulome), then the axillary placentation of this species is also of cauline origin. It then follows as a logical consequence that the gynoecium is acarpellate. Whether this acarpellate condition is primitive or derived from a carpellate organization remains unresolved. In the case of a derivation from a carpellate gynoecium, one would have to postulate a phylogenetic shifting of ovule inception and (or) the reduction of the adaxial portion of a carpel whose margins were confluent and thus formed a more or less cylindrical primordium. Congenital or phylogenetic fusion of the cross zone of a peltate carpel with the floral apex is not even a theoretically possible hypothesis since it is not in agreement with any conceivable ontogenetic and phylogenetic processes.

ISSN:0008-4026    

DOI:10.1139/b79-018

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Forest clearance followed by brush control using Tordon 101 (a mixture of picloram and 2,4-dichlorophenoxyacetic acid), caused a decreased thickness of surface organic matter on power line rights-of-way in northern Ontario. The resultant exposure of mineral soil encourages recolonization by tree seedlings. Surface organic matter loss must therefore be controlled to avoid brush-control problems from seeded-in tree species. Erosion is unimportant in removing litter, but decreased net aerial primary production and hastened organic matter decay following spraying are crucial. Organic matter decomposition is increased because soil temperatures rise when the shading plant canopy is killed by the herbicide. The rise in soil temperature is insufficient, however, to entirely account for the hastened decomposition observed. A low-growing, herbicide-resistant, shade-producing, decay-resistant plant canopy is the ideal as a natural or artificial cover crop for transmission corridors. We conclude that Tordon's capacity to push succession back to an early stage is not related solely to its selective toxicity but also to changes in community metabolism.

ISSN:0008-4026    

DOI:10.1139/b79-019

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Leccinum arenicolaRedhead & Watling sp.nov. is described from coastal sand dunes in Kouchibouguac National Park, New Brunswick, Canada. Its probable mycorrhizal partner isHudsonia tomentosaNutt.

ISSN:0008-4026    

DOI:10.1139/b79-020

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Structural specializations occur in the suspensor at the proembryo stage with the formation of wall ingrowths. Soon after the appearance of the ingrowths, mitochondria, plastids, polysomes, and smooth endoplasmic reticulum greatly increase in their abundance within the suspensor cells. By the late globular stage, wall ingrowths are extremely well developed and the cells within the suspensor are packed with cellular organelles. The nucleus of the suspensor cell at the heart stage also takes on an active appearance. The nucleus becomes highly lobed in shape and micronucleoli can also be found. There is little change in the overall ultrastructural pattern of the cell till the cotyledon stage. At this stage, wall thickening occurs in all suspensor cells and the outlines of most of the ingrowths become less obvious. The mitochondria, plastids, and polysomes become less abundant and a change in the configuration of the smooth endospermic reticulum is also observed. The ontogenetic changes of the cellular organelles suggest that the suspensor plays a role during early embryo development, i.e., globular to early cotyledon stage.

ISSN:0008-4026    

DOI:10.1139/b79-021

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A tissue culture procedure for the establishment, multiplication, and maintenance of genotypes of birdsfoot trefoil,Lotus corniculatusL., is described. Surface sterilization followed by tissue culture of the apical shoot-tip or node sections of the stem produces small shoots within 1 month. Tissue cultures are established faster from node sections than shoot-tip explants, although shoot-tip explants are favoured where surface sterilization is difficult.The addition of the cytokinin benzyladenine in the culture medium enhanced shoot formation from shoot tips and increased the number of shoots produced from shoot-tip and node cultures. Incubation of tissue cultures at reduced temperatures (2–4 °C) for 1 month resulted in very little change in number or height of shoots in the cultures during the incubation period. Plantlets transferred from cultures incubated at low temperature to the growth room had a high survival rate. The tissue culture once established can be subcultured for propagation or storage or returned to the growth room or field as plants.

ISSN:0008-4026    

DOI:10.1139/b79-022

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Organogenesis of the female flower and gynecandrous partial inflorescence is described. Approximately 25 first-order inflorescence bracts are formed in an acropetal sequence. A second-order inflorescence axis, the partial inflorescence, develops in the axil of each bract. Third-, fourth-, and fifth-order axes arise in the axils of second-, third-, and fourth-order bracts. A gynoecium terminates a second-order axis and sometimes a distal third-order axis. A gynoecium consists of two stigmas and one basal, unitegmic, orthotropous ovule. The wall enclosing the ovule, the circumlocular wall, is comprised distally of gynoecial tissue and proximally of tissue of the inflorescence axis and its appendages. The latter portion of the wall is formed by zonal growth. Androecial members, formed proximal to the gynoecium on the partial inflorescence, are carried onto the circumlocular wall by zonal growth. A stamen may develop from the last-formed primordium before gynoecial inception or from a potentially stigmatic primordium. The papillae of the flower and fruit arise as emergences and from potentially bracteate, axial, and staminate primorida during the development of the circumlocular wall. The term circumlocular wall is used in a neutral sense to describe this unique structure. Since the gynoecium is composed of gynoecial appendages and inflorescence axis and appendages, a functional definition of gynoecium must be expanded to include any tissue, including an inflorescence, that surrounds the ovule(s) and forms the fruit(s).

ISSN:0008-4026    

DOI:10.1139/b79-023

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Reproductive buds broke dormancy at the same time as vegetative buds. Pollen mother cells entered prophase of meiosis immediately after dormancy and five-celled, winged pollen was mature about 6 weeks later. Megasporogenesis occurred 3 weeks after microsporogenesis and the female gametophyte was mature in about 6 weeks. Pollination occurred over about 1 week in late May or early June and fertilization occurred about 3 weeks after pollination. One to four archegonia developed. A comparable number of 16-celled proembryos usually developed within 1 week after fertilization and cotyledons began to develop about 1 month after fertilization. Simple polyembryony occurred in most ovules but cleavage polyembryony was not observed. Embryos were fully developed in late August and seeds were mature and shed in September.The small number of archegonia often present, the high incidence of self-pollination, which may have been the cause of the high frequency of early embryo abortion, and the failure of basal and distal ovules to become pollinated were major causes of empty seed.The phenology of reproductive development varied with the site and the elevation but varied little at one site in successive years. Differences were greatest early in the growing season, but by the time of fertilization, higher elevation trees which began development much later had nearly caught up with lower elevation trees and seeds from all sites were mature and shed at about the same time.Reproductive bud dormancy like vegetative bud dormancy was broken in response to photo-period rather than temperature; however, subsequent cone development was greatly affected by temperature.

ISSN:0008-4026    

DOI:10.1139/b79-024

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The effects of SO2(2 ppm for 6 h), O3(0.9 ppm for 5 h), and SO2–O3mixtures (2 ppm SO2and 0.9 ppm O3for 5 h followed by SO2for 1 h) were studied on injury and growth of 4-month-old, actively growing and quiescentUlmus americanaL. seedlings. In actively growing seedlings visible injury to leaves from SO2–O3mixtures was evident within 24 h; from O3within 36 to 48 h; and from SO2within 48 h after fumigation ceased. Sulfur dioxide and SO2–O3treatments reduced expansion of new leaves (< 1 cm long at time of fumigation) within 1 week, but normal rates of leaf expansion were restored by the end of the 2nd week. Ozone had no significant effect on expansion of new leaves. Expansion of young leaves (> 1 cm long at time of fumigation) was markedly inhibited by all treatments; it was inhibited most by SO2–O3, an intermediate amount by SO2, and least by O3. Numbers of emerging leaves were significantly reduced by SO2, and by SO2–O3, but only at the end of the 1st week. After 5 weeks, stem dry weights were reduced by O3and SO2–O3, and root dry weights were reduced by SO2and SO2–O3. In quiescent plants pollution injury to leaves was similar to that in actively growing plants. However, all fumigation treatments induced severe defoliation in quiescent plants.

ISSN:0008-4026    

DOI:10.1139/b79-025

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The effects of SO2(2 ppm for 6 h), O3(0.9 ppm for 5 h), and SO2–O3mixtures (2 ppm SO2and 0.9 ppm O3for 5 h followed by SO2for 1 h) were studied on metabolite contents of 4-month-old, actively growing and quiescentUlmus americanaL. seedlings. Effects on metabolite contents in leaves, stems, and roots were examined 24 h, 1 week, and 5 weeks after exposure to pollutants for actively growing seedlings, and 24 h and 1 week for quiescent seedlings. Fumigations caused significant reduction in total nonstructural carbohydrate and protein contents of actively growing seedlings within 24 h after fumigation. By the end of 5 weeks, however, carbohydrate and protein contents of new (< 1 cm long at the time of fumigation) leaves were comparable with those of control plants, indicating that capacity of new leaves to function was restored. The adverse effects of pollutants on metabolites of older leaves (> 1 cm long) of actively growing seedlings persisted throughout the 5-week period. Changes in lipid contents of actively growing seedlings were small and in most cases not significant. Exposure to pollutants decreased lipid contents of quiescent seedlings (up to 28%); this decrease was much lower than reduction in carbohydrates or proteins (up to approximately 65%). Metabolite contents of both actively growing and quiescent seedlings were reduced most by SO2–O3, an intermediate amount by SO2, and least by O3treatment.

ISSN:0008-4026    

DOI:10.1139/b79-026

出版商:NRC Research Press    

年代:1979

数据来源: NRC