摘要:

The morphology and anatomy of the root system ofLinaria vulgarisis described. The invasive behavior of the plant is related to the growth habit of the root system and to the formation of buds on the roots. The root system is described in terms of a framework of vigorous long roots, each passing through a phase of horizontal growth followed by a phase of vertical growth. Long roots bear lateral roots which mostly appear to be of restricted growth; long roots of the next order are generally initiated in the region where the direction of growth of the parent long root changed. Any lateral root is thought to be potentially capable of developing as a long root. There are no qualitative grounds for a separation of long and short roots, though most roots are restricted in their growth. Bud initiation is a feature only of roots which have developed as long roots. Root buds are not formed from the long root tissues, but from the bases of some of the lateral roots of the long roots, always in regions where the parent long root passed over from horizontal to vertical growth, and occasionally on the horizontal parts of long roots. Bud formation has only been found to occur when some secondary growth is present in the parent long root.

ISSN:0008-4026    

DOI:10.1139/b66-121

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Through inoculation tests in the greenhouse and in the field, the previously unknown 0 and I stages ofColeosporium viburniArth. are shown to occur on jack pine (Pinus banksianaLamb.). These stages are described and differences in aeciospore morphology which permit distinction on pine of this rust fromColeosporium asterum(Diet.) Syd. are discussed. The description ofC. asterumis amended to include differences in aeciospore size between collections on jack and red pine (Pinus resinosaAit.). The known distribution ofC. viburniis summarized.

ISSN:0008-4026    

DOI:10.1139/b66-122

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

InNeurospora tetrasperma, hyphal chromosomes, unlike those within asci, are extremely small. Their appearance and behavior is similar to that previously described by this laboratory for other Ascomycetes. They are linearly arranged, usually upon a fine filament. The filament and the chromosomes together constitute a threadlike nucleus. Double threads, in the form of aYorXor some other configuration, are interpreted as being in division.

ISSN:0008-4026    

DOI:10.1139/b66-123

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

It was observed that when the radicular end of the embryo ofDendrophthoe falcata, a semiparasitic mistletoe, was split longitudinally into two halves and cultured in vitro, each half regenerated into a holdfast. In the present investigation when the radicular end was divided into three parts (by two parallel incisions) three holdfasts were formed, and when two longitudinal incisions were made at right angles to each other, four holdfasts were formed. At the same time observations were made on the growth of various embryonal segments.

ISSN:0008-4026    

DOI:10.1139/b66-124

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Varicosporina ramulosa, a staurospore-producing fungus, shows a range of morphological characteristics in response to salinity, pH, nutrients, and other changes in the culture medium. Variations in sporulation include encystment of mycelia and conidia, production of chlamydospores, and differences in concentrations of conidium production. Optimal conditions for mycelial growth differ from those stimulating reproduction. These factors possibly affect distribution of the species in the sea and may be significant in the observed paucity of morphologically adapted aquatic Hyphomycetes in estuarine localities.

ISSN:0008-4026    

DOI:10.1139/b66-125

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Leptosphaeria avenariaWeber f. sp.avenariahas thePleosporatype of centrum development. The perithecium locule is created principally through the basipetal growth of pseudoparaphyses and to a lesser degree by the lysis of pseudoparenchyma at the base of the perithecium. The ascogonium produces an ascogenous system that fragments into many uninucleate and binucleate cells which eventually line the lower margin of the locule. An ascogenous cell forms a single crozier, or up to eight croziers by proliferation. The penultimate cell develops into the ascus in which, after meiosis and one mitosis, eight uninucleate ascospore initials form. Two mitotic divisions with accompanying cell divisions produce the mature ascospore composed of four uninucleate cells. Asci mature successively; only a few are mature at one time. The ostiole is formed schizogenously and is lined with periphyses.

ISSN:0008-4026    

DOI:10.1139/b66-126

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Uromyces intricatusis broken into six varieties. Var.umbellatiand var.majorattack montane and lowland species ofEriogonumsubgen.Eueriogonumin much of western North America, and the former probably attacksOxytheca. Vars.intricatus(Oregon, California),parvifolii(California),nivei(interior British Columbia to Arizona), andpluriporosus(mainly Montana, Wyoming, and Colorado) attack various species or species groups inEriogonumsubgen.Oregonium, the variation being partly geographic and partly due to host specialization. Var.intricatusattacksChorizanthespp. andEriogonumsubgen.Ganysmain California. This variety has met and intergraded with var.pluriporosusin the past but the link is now broken.Uromyces bisbyi, a microcyclic derivative of var.parvifolii, is described onEriogonum parvifoliumin California. The implications on the evolution ofEriogonumand the problem of realistic nomenclature of rusts derived from both host and geographic isolation are discussed. A table clarifies the nomenclature of reported host plants.

ISSN:0008-4026    

DOI:10.1139/b66-127

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The perfect state ofDothistroma piniHulbary was found on native and exotic pines in British Columbia. It is described as a new species ofScirrhiaFuckel, and the nameS. piniis proposed. The life history, cultural characteristics, and distribution are presented.

ISSN:0008-4026    

DOI:10.1139/b66-128

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The flavonoid patterns of 11 taxa ofTrifoliumL., sect.Lupinasterwere examined chromatographically. On the basis of the coded data the coefficients of association between the various taxa were determined and a hierarchic system based on chemical evidence established. The methods permitted objective numerotaxonomical use of chromatography to establish and support hierarchic systems and to express the relationships in definite and comparable mathematical terms.T. parryiandT. parryi salictorumwere found to be very closely related.T. attenuatum, T. brandegei, andT. haydeniiformed the next most related group, whileT. kingii, T. dasyphyllum, T. alpinum, T. nanum, T. longipes, andT. latifoliumformed a large, somewhat unrelated group of species.

ISSN:0008-4026    

DOI:10.1139/b66-129

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Populus tremuloidesMichx. (trembling aspen), a commercially valuable tree, generally reproduces vegetatively by shoots (suckers) that arise adventitiously on lateral roots. Among various ecological factors, temperature plays a significant role in sucker initiation. The influence of five temperature regimes on suckering is reported here. Root cuttings of aspen, 10 cm long and 1.2 to 2.5 cm thick, were grown in the dark in fine sand. The temperature of the sand was kept at 58°, 64°, 74°, 87°, and 95 °F, and the moisture content near field capacity. The earliest emergence of suckers was at 87°. The maximum incidence and growth of suckers was at 74°, declining gradually below and above this temperature. Sufficient food material is stored in short root sections to sustain suckers for more than 3 weeks. These data agree with our field observations and indicate that after such disturbances as cutting and burning, insolation-induced increase in soil temperature is the cardinal factor for sucker stimulation.

ISSN:0008-4026    

DOI:10.1139/b66-130

出版商:NRC Research Press    

年代:1966

数据来源: NRC