Waste Places Research Articles

Senecio esleri(Asteraceae), a new fireweed

Abstract A new species of erechtitoid Senecio is described based on New Zealand material. S. esleri is an annual, or rarely a short-lived perennial, herb found in waste places and coastal habitats in Northland and the Auckland area. It has previously been confused with the Australian fireweed S. bipinnatisectus and is best distinguished from that species by the setose stems, less divided lower leaves, greater number of involucral bracts, and hairier achenes. Its distribution and habitats indicate that it is naturalised in New Zealand, most probably from Australia.

THE BIOLOGY OF CANADIAN WEEDS.: 91. Malva pusilla Sm. (= M. rotundifolia L.)

This account provides information on the biology of round-leaved mallow, Malva pusilla Sm. (= M. rotundifolia L.). Primarily a weed of gardens and waste places, it has recently become troublesome in field crops causing yield losses of up to 90% in flax and lentil and up to 30% in wheat. Introduced from Eurasia, it is common mainly in the prairie provinces. Although often confused with two other weedy mallows, M. neglecta Wallr. and M. parviflora L., it has a different geographical distribution and can easily be distinguished by its short petals with bearded claws. Malva pusilla propagates by seed which are impermeable to water, exhibiting low germination unless scarified, and therefore capable of remaining dormant for long periods. Plant growth form varies greatly with competition. Round-leaved mallow is difficult to control chemically, but it can be effectively controlled with a fungus which is being developed as a commercial bioherbicide.Key words: Malva neglecta, Malva parviflora, Round-leaved mallow, weed biology

Some aspects of nitrogen, phosphorus, and potassium nutrition of three colonizing beach species

The culture of three colonizing dune species in hydroponics indicated that nitrogen (N), phosphorus (P), and potassium (K) were essential for high plant productivity. The K requirement of Oenothera biennis was lower than that of Cakile edentula or Corispermum hyssopifolium. The dry weight per plant of O. biennis was greater at higher concentrations of N, P, or K; however, the dry weight per plant of Cor. hyssopifolium was similar at all concentrations except in the complete absence of N, P, or K. Cakile edentula did not grow well under any of the nutrient concentrations, probably because of a poor response to hydroponic solutions. The number of live leaves and leaf area of O. biennis and Cor. hyssopifolium were affected more by a lack of N and P than K. The nutrient requirements of Cakile edentula were substantially higher than those of either O. biennis or Cor. hyssopifolium. It is suggested that the hierarchy in plant size and seed production in field populations may result from variability of available nutrients. Oenothera biennis, a generalist weedy species of farmland, old fields, waste places, and sandy beaches, was less exacting in its requirements of N, P, and K than the two beach specialists, Cakile edentula and Cor. hyssopifolium.

THE BIOLOGY OF CANADIAN WEEDS. 83. Hypericum perforatum L.

Hypericum perforatum L., St. John’s-wort is an introduced weed growing in waste places, roadsides, rangelands, pastures and similar habitats of Eastern Canada and British Columbia. It is poisonous to livestock causing a photosensitization in grazing animals with light-colored hair. In Canada, two introduced leaf-feeding beetles Chrysolina quadrigemina and C. hyperici have provided effective control. In Nova Scotia an endemic host-specific "strain" of Colletotrichum gloeosporioides generally maintained this weed at low levels, particularly in lowbush blueberry fields. It spreads both by seeds and vegetatively by rhizomes. Details related to its morphology, reproductive biology, responses to human manipulation, parasites and control measures are summarized.Key words: Hypericum perforatum, weed biology, review

THE BIOLOGY OF CANADIAN WEEDS.: 84. Oenothera biennis L.

Oenothera biennis L., the common evening-primrose, is a widespread weed of roadside and waste places commonly occuring on light sandy or gravelly soils where competition is limited. The species is native to North America and, although occurring in all 10 Canadian provinces, is more common in the east than in the west. The chief factor contributing to its success as a weed is the ability to tolerate drought. A winter annual or facultative biennial, it flowers and bears seed only once in a lifetime. The small, irregularly shaped seeds have a high oil content, and contain γ linolenic acid, an uncommon fatty acid of pharmaceutical value. Oenothera biennis is a true-breeding translocation heterozygote composed of two genomes (complexes) differing genetically as well as in chromosomal end arrangement. Populations of O. biennis consist of numerous inbreeding lines, between which limited hybridization may occur.Key words: Common evening-primrose, Oenothera biennis, weed biology, population structure

Rolf Boldrewood’s *War to the Knife*: Narrative Form and Ideology in the Historical Novel

In The Historical Novel, Georg Lukacs suggested that Sir Walter Scott's limited understanding of the historical present did not prevent him, as a writer, from laying bare the significant forces of social change. Scott's Australian disciple, Rolf Boldrewood, was a similar case: a popular writer of limited understanding whose novels are nonetheless deeply significant portraits of Australian society in the years before Federation. Boldrewood's diaries of the 1890s, for example, rarely acknowledge the tumultuous events of this period: the maritime, coal miners' and shearers' strikes, the rise of the labour and women's movements, and Australia's increasing military involvement in South Africa. But in War to the Knife, the novel he wrote in 1898, these conflicts were displaced into history. War to the Knife has the classic structure of the historical novel, bringing two representative groups into conflict during the Waikato War in New Zealand during the 1860s: the Maori and the Pakeha, the one a noble aristocratic race doomed to pass into history, the other powerful, pragmatic, and destined to transform the waste places of the world through commerce. At the centre of these two contending forces is the Waitara Block, a parcel of land held communally according to Maori tradition, but claimed by British commercial enterprise.

THE BIOLOGY OF CANADIAN WEEDS.: 74. Fagopyrum tataricum (L.) Gaertn.

Fagopyrum tataricum (L.) Gaertn, is an annual plant that has been grown as food for human and domestic animal consumption in the Canadian maritime provinces, but it is a serious weed in north central and north eastern Alberta and in certain parts of Manitoba and Saskatchewan. The weed occurs in a wide variety of habitats, including spring cereal and oilseed crop fields, waste places and roadsides. It causes reduced crop yields, dockage losses, cleaning costs, lowering of grade and quality, and necessitates costly chemical and cultural control measures. Fagopyrum tataricum seeds are difficult to remove from wheat. The weed can be controlled with a number of foliage-applied herbicides.Key words: Weed biology, tartary buckwheat, sarrasin de tartarie, Fagopyrum tataricum

THE BIOLOGY OF CANADIAN WEEDS.: 66. Artemisia absinthium L.

Biological data are summarized for Artemisia absinthium L., an introduced species that has escaped from domestication where it was grown for its medicinal properties. It is a weed of roadsides, waste places, farmyards, gardens, and shelter-belts and although found in every province and the northern United States, it is particularly prevalent in the prairie provinces and the northern great plains states. It can be controlled by cultivation but is capable of invading overgrazed pastures, hay fields and croplands that are periodically disturbed. It is generally a poor competitor and can be controlled by grass competition and by herbicides.Key words: Absinth, Artemisia absinthium, weed biology

THE BIOLOGY OF CANADIAN WEEDS.: 64. Datura stramonium L.

Datura stramonium L. (Solanaceae) is an annual weed found in most temperate and subtropical regions of the world. It has been recorded from all the provinces of Canada except Newfoundland, but is most common in Ontario and Quebec. It occurs in waste places, gardens, barnyards and, increasingly, in cultivated fields. Datura stramonium serves as an alternate host for many insect pests and diseases of Solanaceous crops, such as tomatoes, tobacco and potatoes, and has both narcotic and medicinal properties due to its production of a variety of alkaloids. It has been used extensively as an experimental plant in studies of genetics, chromosome morphology and embryonic development.Key words: Weed biology, jimsonweed, Datura stramonium, distribution

THE BIOLOGY OF CANADIAN WEEDS.: 63. Sonchus asper (L.) Hill and S. oleraceus L.

Spiny annual sow-thistle (Sonchus asper (L.) Hill) and annual sow-thistle (S. oleraceus L.) are introduced weeds which occur in the agricultural regions of all Canadian provinces, but are most abundant in disturbed habitats in southern Quebec, Ontario, and British Columbia. They occur on a wide variety of substrates and are common weeds of waste places and gardens. Their intermittent and prolonged emergence period, rapid development to maturity, and production of large quantities of highly-dispersive seeds make them difficult to control. Details of the morphology of the annual sow-thistles, their reproductive biology (including previously unpublished material on population dynamics and seed production), their response to parasites, and methods of control are presented.Key words: Biology of Canadian weeds, Sonchus oleraceus, Sonchus asper

Ecophysiological Studies of Eleusine indica (L.) Gaertn. and Sporobolus pyramidalis P. Beauv. at Ibadan, Nigeria

Eleusine indica and Sporoboluspyramidalis are common grasses in the tropics, including Ibadan, Nigeria. The former is considered a good fodder when young, but the latter has low grazing quality. The objective of this study was to describe some of the morphological characteristics of these 2 prominent species. S. pyramidalis is a taller grass having more roots per culm and a longer inflorescence. Seeds of the 2 grasses germinated between 200 C and 350 C and emergence declined with increasing depth until it was zero at and 4 cm for E. indica and S. pyramidalis, respectively. S. pyramidalis had a higher rate of germination. The 2 species have stomata on both leaf surfaces, but the number is greater on the adaxial surface. Experiments indicate that E. indica is more tolerant and adaptable to biotic disturbances. The biomass contribution by E. indica and S. pyramidalis is estimated at 1,100 kg/ha 300 kg/ha, respectively. A knowledge of the developmental physiology of grasses is of considerable importance in the management of grasslands. The present investigation of the tropical grasses Eleusine indica (L.) Gaertn. and Sporoboluspyramidalis P. Beauv. is a contribution to our understanding of their ecology and will likely aid the agriculturist in managing these species. E. indica, commonly known as fowl-foot grass, has been described by Purseglove (1975) as a successful species of Africa and Asia and is now widely spread throughout the tropics of both hemispheres. It has been introduced into the United States where it is a weed common to many of the warmer states. In the tropics, it grows from sea level to about 1,800 m. The species is particularly common in waste places and along road sides and paths. It was considered a good fodder when Young and Bogdan (1977) further reported it as palatable to cattle in Fiji, Hawaii, South America, and other areas of the world. S. pyramidalis is another common grass in Nigeria (Stanfield 1970). It is a tufted perennial plant having low grazing quality and is considered unpalatable to livestock. It has been observed that the population of E. indica is affected by grazing in preflowering condition. The spread of the plant depends mainly on seeds. Both species are adversely affected by repeated cutting. McIllroy (1964) reported that E. indica thrives well in trampled areas and becomes dominant along cattle tracks and paths. Our observation is that both species are conspicuously absent under shade.

THE BIOLOGY OF CANADIAN WEEDS.: 56. Xanthium strumarium L.

Xanthium strumarium L. is an annual weed found in all provinces of Canada except Newfoundland, and throughout the temperate and subtropical regions of the world. It occurs in ruderal habitats, waste places, agricultural fields, and along watercourses, beaches and coastal dunes. Throughout its range, populations vary widely in fruit size and morphology and in photoperiodic requirements. It has been used extensively as an experimental plant in studies of floral induction, leaf development, stomatal control, seed germination, and biological control.Key words: Cocklebur, reproductive biology, weed, Xanthium

THE BIOLOGY OF CANADIAN WEEDS.: 57. Trifolium repens L.

Trifolium repens L. (wild white clover) is the most important pasture legume in many parts of temperate zones and is distributed widely in Canada, occurring in every province and both territories. It is also an agricultural escapee and is often continuous over large areas of roadsides and waste places, and is a common seed impurity in many seed mixtures. This account is a summary of the biological information on white clover.Key words: Trifolium repens, white clover

Regulation of Fruit and Seed Production in An Annual Legume, Cassia Fasciculata

This study examines the factors that limit female reproductive function (fruit and seed production) in the annual plant, Cassia fasciculata Michx. (Leguminosae), an hermaphroditic herb that inhabits prairies, open woods, and waste places in the eastern USA. Removal of competitors and addition of water to plants in the field showed that resource levels prior to fruit influence plant size which, in turn, is positively related to the number of fruit matured. Manual addition of pollen to flowers in the field did not increase the number of fruit matured, suggesting that fruit production was not pollinator limited. Removal of rapidly growing fruit resulted in growth and maturation of fruit that normally would not have matured, indicating that resources limited fruit production. In four populations studied, 24—70% of initiated fruit matured, 12—40% aborted or died, 3—31% were still developing at the time of plant death, and 61—12% were lost to predators. In fruit that matured, between 23% and 73% of initiated seeds reached maturity, 22—43% were aborted, and 0—49% were lost to seed predators. These data indicate that seed production was limited by resources and seed predators. It is hypothesized that overinitiation of fruit in C. fasciculata is an adaptive response to either; (1) the loss of juvenile fruits to seed predators, (2) variation in fruit quality coupled with the ability of the plant to selectively mature high—quality fruit, or (3) unpredictability of resource levels and survival during fruit filling. The generally low levels of predation on juvenile fruits make the first hypothesis unlikely for C. fasciculata. Plants did, however, selectively mature fruit with large numbers of developing seeds. Furthermore, variation in the number of fruit matured per inflorescence seemed to be related to variation in precipitation and plant survival through the fruit—filling period. Thus, the data support both the second and third hypotheses.

THE BIOLOGY OF CANADIAN WEEDS.: 55.: Ambrosia trifida L.

Giant ragweed, Ambrosia trifida L., is a weed of wet low-lying pastures, cultivated fields, orchards, roadside ditches, river banks, and waste places, particularly in southern areas of Manitoba, Ontario, Quebec and the Maritime provinces except Newfoundland. Original research and published information were incorporated into an account on the biology of this weedy, wind-pollinated species. The airborne pollen is known to cause considerable hay fever.

THE BIOLOGY OF CANADIAN WEEDS.: 52. Achillea millefolium L. S.L.

A review is provided of information on the biology of yarrow (Achillea millefolium L., sensu lato) a very complex polyploid group in Canada. Native variants occur across Canada and consist of both tetraploid and hexaploid races. Introduced hexaploids occur predominately in eastern Canada. Yarrow is found as a weed in pastures, meadows, lawns, roadsides and waste places. The species has a wide climatic range and is particularly drought-tolerant. Vegetative spread is rapid, increasing competitive advantage in closed communities, whereas seed reproductive allocation is low. Plants of the species are self-incompatible and insect-pollinated. Factors affecting seed germination are summarized; these include response to temperature, moisture, light, seed age, nitrate ions, sowing depth and fertilizers. Yarrow control in pastures may be provided by 3,6 dichloropicolinic acid or herbicide mixtures containing diclorprop or mecoprop.

THE BIOLOGY OF CANADIAN WEEDS.: 41. Lotus corniculatus L.

This summary of biological data is for bird’s-foot trefoil, Lotus corniculatus L., which is weedy in Canada, particularly in eastern Canada and the Fraser valley of British Columbia. Bird’s-foot trefoil is an agricultural escapee and is often continuous over large areas of roadside and waste places. It can be controlled by the use of several common herbicides.

The ecological life cycle of Thlaspi perfoliatum and a comparison with published studies on Thlaspi arvense

Summary: Thlaspi perfoliatum L. is an introduced winter annual that grows in waste places, but it is not a troublesome agricultural weed. Seeds are dormant at maturity in spring, afterripen during summer and germinate in autumn. Non‐dormant seeds that fail to germinate in autumn are induced into secondary dormancy by low winter temperatures and cannot germinate the following spring. These seeds afterripen during summer and germinate in autumn if conditions are suitable. Vernalization is not an absolute requirement for flowering. However, it shortens the time to flowering, and vernalized plants produce many more flowers and seeds than non‐vernalized plants. Results from studies on seed germination and flowering of T. perfoliatum are compared to published studies on the life cycle of Thlaspi arvense L., an introduced species that is a serious agricultural weed which behaves both as a winter and a summer annual.

Field and laboratory germination responses of achenes of Polygonum lapathifolium, P. pensylvanicum, and P. persicaria

The annual smartweeds Polygonum lapathifolium L., P. pensylvanicum L., and P. persicaria L. are weeds of cereal crops, waste places, and wet ground in Canada. Their ‘weediness’ is attributed, in part, to the production of large numbers of achenes which are capable of lying dormant in the soil for several years or until suitable conditions arise for germination.Dormancy–germination characteristics of achenes from Ontario plants were examined in the laboratory and in the field. Three types of dormancy have been identified, each of which prevents germination under a different set of unfavourable conditions. An innate dormancy prevents germination in fresh achenes immediately prior to winter. An enforced dormancy prevents germination during the winter and in achenes which are deep in the soil. An induced dormancy is caused by hot or dry periods (at least in P. persicaria). Germination occurs as a series of flushes whenever achenes are brought to the soil surface and (or) whenever rainy spells occur.

THE BIOLOGY OF CANADIAN WEEDS.: 27. AVENA FATUA L.

This contribution on Avena fatua L., wild oats, is part of a series which presents biological information on plants that are weedy in Canada. Wild oats rate as by far the most serious annual weed of cultivated fields in the prairie provinces of Canada. The weed occurs in a wide variety of habitats: spring cereal and oilseed crop fields, fallow fields, roadsides, waste places, gardens and other habitats disturbed by man. Seed dormancy and irregular germination throughout the growing season are the most important features contributing to the persistence of wild oats. The weed is susceptible to a number of soil- and foliage-applied herbicides.