THE BIOLOGY OF CANADIAN WEEDS. 42. media (L.\ Yill.

ROY TURKINGTON, NORMAN C. KENKEL, and GAIL D. FRANKO Department of Botany, University of BritishColumbia, Vancouver, BritishColumbia V6T 28 I . Received 7 Jan. 1980. accepted 20 Mar. 1980.

TunruNcrou, Roy, KnNrnr-, NonrueN C. eNo Fnnr..rro, Gerl D. 1980. The biology of Canadian weeds. 42. (L.)Yill. Can. J. Sci. 60: 98r-992.

This paper provides a summary of biological data on Stellaria media (L.) Yill., commonly known as chickweed. It is found throughout most of the world and is present in all Canadian provinces and both territories, being particularly abundant in British Columbia and eastern Canada. Chickweed is a weed of grain fields, young pastures, lawns, and gardens, and can be controlled by the use of several common herbicides.

La Stellaire moyenne, aussi connue sous le nom de Mouron des oiseaux (Stellaria media L.), se rencontre dans presque toutes les parties du monde et elle a colonis6 toutes les provinces et les deux Territoires du Canada. Elle est particulibrement abondante en Colombie-Britannique et dans I'est du Canada. La stellaire est une mauvaise herbe des c6r6ales, des jeunes pitures, des pelouses et des jardins. On dispose contre elle de plusieurs bons herbicides.

1. Names leaves opposite, broadly oval and pointed, Stellaria media (L.\ Vill. chickweed entire, glabrous; lower leaves 3-20 mm, (Canada Weed Committee 1975),- stellaire stalked, the petiole with a single line of hairs; moyenne (Ferron and Cayouette 1975), upper leaves to 25 mm, sessile; flowers mouron des oiseaux (Conners 1967). solitary in the leaf axils, or from few to many , pink family, Caryophyl- and borne in axillary or terminal cymes, lac6es. star-shaped (hence Stellaria) (Fig. 2B), 5 The species is occasionally referred to as mm in diameter on short peduncles; sepals 5, Alsine media L. (Liive and Liive 1975). The separate, hairy, 4.5-5 mm; petals 5, white, authority for the name Stellaria media is deeply bifid, shorter than sepals; styles 3; often cited as "(L.) Cyrillo" rather than stamens 3-10; anthers red-violet; capsules "(L.) Vill" (Hitchcock and Cronquist 19731, longer than sepals, opening by 6 teeth to Hult6n 1970; Taylor and MacBryde 1977). release an average of 8- I 0 seeds; seeds (Fig . This is an error in the attribution of the 2A, C, D) 0.9-1.3 mm across, yellowish to authority for the transfer of the epithet media dark brown, flattened, almost circular, fromAlsine to Stellaria (Burnat 1892). sometimes narrowed to base, with 5-6 rows of low protuberances, maturing rapidly; 2. Description and Account of Variation flowers produced throughout the growing (a) S. nedia is an annual or winter annual season. with a slender tap root; diffusely branched A chromosome number of 2n : 20 II has stems, either decumbent or ascending (Fig. been reported from the Queen Charlotte l), 5-40 cm, round in cross section with a Islands (Taylor and Mulligan 1968) and single line of hairs down each internode; from Ontario (Mulligan 196l). Mulligan

Can. J. Plant Sct , fr: 9tt-992 (Jdy r9E0) (pers. comm.) has unpublished counts of S. 98r 982 CANADIAN JOI.JRNAL OF PLANT SCIENCE

i' I' [' [' l4 Lu

l. Stellaria mt wk-old adult plant and (B) lO-day-old seec

B mm I '1 I lffi s,l ,J Fig.2. Stellctria media (B) flower, (C) seed x l seedreed coat TURKINGTON ET AL STELLARIA MEDIA (L,) VILL -

D

.\

Fig.2. Stellaria media (L.) Vill. (C) and (D) taken with scanning electron microscope. 984 CANADIAN JOURNAL OF PLANT SCIENCE

media from four locations in Ottawa; all 3. Economic Importance formed 20 bivalents at metaphase I of (a) Detrimental Canada, S. media is a meiosis. Counts of 2n : 28,36, 40, 42 and weed of grain fields-ln and other cultivated 44 have been reported from Eurasia with 2n areas and pastures. It can be a major : 40 predominating (Federov 1974; Love contaminant among some crops; e.g. on and Lcive 1975; Moore 1973). Westham Island in the Fraser Delta, it has > (b) Stellaria media is similar to Cerastium l5Vo cover among raspberry and strawberry fontanum, C. arvense and S. graminea, but crops, and from 80 ao l0OVo cover in barley it differs from all these in its distinctive and potato crops. Comparable data are not pattern of pubescence, i.e. a single line of available for elsewhere in Canada. S. media hairs down the stems and petioles. competes with crop by shading and smothering young seedlings with its mat-like growth (Fryer and Makepeace l9'l'7). Mann (c) S. media expresses a high degree of and Barnes ( 1950) reported a 66-807o loss in phenotypic plasticity and genotypic flexibil- a barley crop due to chickweed competition ity (Sinha and Whitehead 1965), varying in for root space. Barley and chickweed roots size, habit, hairiness, length of petals, grow at the same level but the chickweed number of stamens, and number, size, and grow When grown the surface details o[ seeds. roots faster. together weed can absorb nitrogen more readily than Using such characteristics as calyx and barley. England, O'Leary (1973) sur- corolla length, number of stamens, and the In veyed 5300 fields spring winter shape of petals, B6guinot (1921, cited in of and cereals and found chickweed to be the most Matzke 1932) described 32 varieties of S. media. abundant weed. S. media seeds are contaminants in seeds of wheat, barley, rye, Kraft (1917) observed a reduction in the oats, timothy, rape, swede, mustard, fodder number and size of petals in plants of both poor and very rich soils. beets, sugar beets and kale (Fryer and Makepeace 1977). Matzke (1932) observed that flowers with media capable accumulating from2 to l0 stamens may occur on the same S. is of nitrates to potentially toxic levels (Case plant. Reincihl (1903) reported that lighr and 1957), and grazing of the weed may cause moisture determine the number of stamens in digestive disorders sheep and goats chickweed, but there has been no subsequent in (Carruthers and evidence to support this f,rnding. 1903). It harbors viruses fungi which overwinter between crop Peterson's ( 1936) transplant study plantings (Converse 197 showed clear ecotypic differentiation into and Stace-Smirh l), nematodes which arctic/subarctic populations and Mediterra- as well as aphids and transmit viruses to crop plants (Fryer and nean populations. Germination is delayed in Evans 1968). In some cases, viruses may be the former with subsequent rapid develop- transmitted seeds media ment and sparse vegetative growth. The via the of S. (Provvidenti 1975). latter germinate almost immediately, de- velop over a longer growing season and have (b) Beneficial Chickweed "can prevent luxuriant vegetative growth. Peterson erosion, preserve- and (1936) also distinguished between maritime soil soil structure regulate (Fryer and Makepeace (rapid germination) and continental forms fertility" (delay before germination). 1977) . It is a source of food for animals, the plant being eaten by hogs and rabbits (Spencer 1940) and the seeds by birds (d) Figures I and 2 show the main (Hatfield 1970). Man sometimes uses the diagnostic features of a flower, seed, plant for salads (Grieve 1959). seedling, and 5-wk-old plant of S. media. In Switzerland, chickweed is used in weed MEDIA (L.) V[L. 985 TURKINGTON ET AL. - STELLARIA controMnfestations of Convolvulus arven- It is found widely on every continent, sis and C. sepium in vineyards are from Spitzbergen at 79'N (Hult6n 1970) to suppressed by chickweed. The chickweed the Subantarctic islands at 60'5 (Walton itself is not a problem (Stalder et al. 1913). 1975). While it is generally absent only from the most arctic regions and very dry areas, it (c) Legislation S. media is listed as a is comrnon in the tropics only at high noxious weed in- the Noxious Weeds Act of elevations, e.g. 1300m in KenYa. Alberta and Manitoba. It is named in the Canada Seeds Act and Regulations 5. Habit (Anonymous 1967), where the percentage of (a) Climatic requirements - Chickweed the weed seed affects the grade of grass generally prefers cool temperatures: Walkey mixtures. and Cooper (1976) reported an optimum of 22"C for laboratory populations. However, 4. Geographical Distribution it can obviously tolerate cold conditions The distribution of S. media in Canada and since its range extends into the Arctic and adacent Alaska is shown in Fig. 3. It is Subantarctic regions. It does best in moist found from Vancouver Island to Newfound- regions, persisting and even flowering land, and from the United States border to throughout the winter in cool, moist climates the MacKenzie delta at 69'N. It is more such as in southwestern B.C. (Kenkel, common in B.C. and eastern Canada than in unpublished). But it will not flower during the prairies (Groh and Frankton 1946, winter months if the temperature remains 1948). below 2'C (Moss l9l4). It cannot tolerate

tz-ettt j*s= !+:= - 0o\ )

Fig. 3. The distributio n of Steltaria media (L.) Vill. in Canada and part of Alaska from specimens in the herbaria of the Biosystematics Research Institute, Ottawa, University of Saskatchewan, University of Alberta, and University of British Columbia. The solid line represents the northern limit of distribution as shown ty Hult6n ( I 970). Note that a few specimens have since been collected north of Hult6n's line. The values below the map represent the frequency of the species as recorded in longitudinal belts by two canadian weed Surveys (Groh and Frankton 1946, 1948). 986 CANADIAN JOI.]RNAL OF PLANT SCIENCE dry conditions, and during hot, dry summers common when collected by Holmes in will die back (Roberts and Dawkins 1967). Montreal in 1821, and Cochran identified it Chickweed prefers partially shady condi- in Nova Scotia in 1829. St. Cyr collected it tions such as found near buildings (King on the Isle d'Anticosti in 1882 (Rousseau 1966) and under the cover of row crops. It is 1968) and it was listed as a farm weed in often found growing in gullies, track marks, Canada by Clark and Fletcher (1909). etc. which provide a suitable microclimate of moisture, humidity and shelter. 7. Growth and Development (b) Substratum Chickweed grows on (a) Morphology "The ability of Stellaria most types of soil- (Salisbury 1974) but does media to have achieved- such success best on moist, heavy (King 1966), high can only be attributed to the remarkable nitrogen soils (Roberts 1962) such as found intrinsic variability which is attested in so in chicken coops and cow barns (King 1966) many features . . . (and) . . . is paralleled and on the guano rocks of the Scilly Isles by a physiological variability" (Salisbury (Lousley 197 l) . lt prefers a pH of 5 .2-8.2 1964). (Lefevre 1956) but has been found on soils Like most weedy annuals, S. media has with a pH of 4.8. At these levels growth is numerous, small, easily dispersed seeds and reduced,,often due to aluminum toxicity it has the additional advantage ofbeing able (Buchanan et al. 197 5). Aluminum concent- to flower and set seed throughout the year. rations greater than 2 ppm cause toxicity Dry weight distribution studies (Tprkington, symptoms (Gilbert and Pember 1935). unpublished) show that chickweed allocates only 6Vo of its total dry weight to roots while (c) Communities in which the species occur channeling 76Vo into stem and leaves, an - S. media grows in young or disturbed advantageous strategy for colonizing. communities such as cultivated areas, young Under suitable conditions partial pastures, gardens, lawns and waste places. shade, rich, damp, disturbed soil the Some of the crops with which it grows are stems of S. media will root at the- nodes listed in Section 3a. The only data on weedy (Frankton and Mulligan 1970). This is an associates in Canada are from the Fraser advantageous characteristic to the species in Delta. There, S. media grows with Mat- newly disturbed habitats. ricaria matricarioides (Less.) Porter, Polygonum lapathifolium L., Senecio vul- (b) Perennation Chickweed is able to garis L., Amaranthus retroflexus L., grow at 2'C when- most plants cannot (King Chenopodium album L., Capsella bursa- 1966). In colderenvironments it overwinters pastoris (L.) Medic.,,4 gropyron repens (L.) as seed; in mild climates, it is a winter Beauv. and Poa annua L. annual, being able to overwinter after fall germination. This has been reported from 6. History England (Heathcote and Byford 1975) and Stellaria media is native to and seeds has been observed in southwestern B.C. of the species have been found in preglacial (Kenkel, unpublished). Peterson (1936) and mesolithic deposits in Britain (Salisbury describes ecotypes that are adapted to cold 1964). It is believed to have been in winter temperatures Greenland from the 1400's to 1721. before the period of European settlement (Pedersen (c) Physiology Individual plants living 1972). How or when the species was through the winter- show a shift in storage introduced to N. America is not known, but physiology from summer starch to winter in 1672, Josselyn (cited by Rousseau 1968) sugar. High concentrations of sugar sap in recorded the species in New England. It was winter ensure a high osmotic value in cells, MEDIA (L.) V[L. 987 TTJRKINGTON ET AL. - STELLARIA preventing iie crystal formation (Salisbury study at the University of British Columbia. 1Sl+1. The numbers of seeds per plant range from 500 (Long 1938) to 2500 (Salisbury 1964), (d) Phenotogy Chickweed is a day- and the number of seeds per hectare rangls neutral species- (Fryer and Makepeace from 5.1 million to 15 million (Long 1938; 1977). Under suitable conditions, flowering Roberts and Dawkins 1967). takes place throughout the year as does Seeds are dispersed in a number of ways: maturaiion and shedding of seed. During the by footwear, through the digestive tracts of winter, flowers tend to be without petals, birds, cattle, horses and pigs (Salisbury and are self-fertilized (King 1966). A1- 1964), by ants (King 1966) and by wind though seeds will germinate at any time of (Grieve 1959). The seed is also dispersed as the year under suitable conditions, most a contaminant in pasture mixtures or seeds of germinate and establish in early spring and other crops' late fall (Roberts and Dawkins 1967). Caspers (197'7) followed the seasonal (c) Viability of seeds and germination - changes of caloric values and ash content of Shed seeds of chickweed have 9O-lOOVo the aboveground portion of chickweed. viability. Champness and Morris (1948) Generally, caloric values are highest in found that seed viability is highest in acid, February and lowest between August and waterlogged soils. A high proportion of total October. Ash contents are highest in October emergence occurs within the first few and lowest in February. months after dispersal (except in dry summers (Roberts 1964). FrYer and (e) Mycorrhizo No mycorrhizal associa- Makepeace (1977) found 95Vo germination, tions have been reported.- and Toole and Brown (1946) found 97Vo viability I yr after shedding. Roberts (1964) 8. Reproduction dry-stored seeds for several months, then (a) Floral biology S. media'is cleis- planted them, and after 3 yr found that togamous and almost- homogamous (Salis- 7O.6Vo emerged, SVo werc dormant and bury 1974), self-pollinated (Mulligan and 24.4Vo were not accounted for. Toole and Kevan 1973) and self-fertilized (Mulligan Brown (1946) reported 22Vo viability after and Findlay 1970). Mulligan and Kevan l0 yr and Fryer and Makepeace (1977), (1973) reported that no insects visited the claimed that a proportion of seeds will flowers in their studies, an expected result in survive more than 60 yr when deeply buried cleistogamy; but in European studies, under grass. Seeds subject to severe oxygen Proctor and Yeo (1973) reported visits by starvation (partial pressure Oz < 8) will ichneumon wasps, and Knuth (1908) remain in a dormant condition (Mullverstedt recorded visits by members of the Diptera, 1963). Hymenoptera and Thysanoptera. Gilkey Although many of the results regarding (1957) reported that bees are attracted by the germination are conflicting, certain general flower fragrance. features are evident. The optimum constant temperature for germination is between l2"C (b) Seed production and dispersal The and 20oC, and while germination can take mean weight of 1000 chickweed seeds- has place at 2"C or even less, a cold treatment been reported as 0.362 g (Whitehead and will often induce a light requirement. High Sinha 1967) and 0.505 g (King 1966). The temperatures are inhibitory and germination numberofseeds perfruitranges from I to 20 does not occur when the temperature (Salisbury 1964) although l0 is average. exceeds 30"C. Daily alternations of tempera- Franko (unpublished) counted an average of ture enhance germination. Germination of 9 seeds per fruit with a top value of 18 in a freshly harvested seeds does not seem to be 988 CANADIAN JOI.JRNAL OF PLANT SCIENCE promoted by light, and strong illumination grows most rapidly just after germination but may inhibit it. After-ripening occurs both in dies back as dry, hot summers or cold dry and in moist storage, but seeds that have winters set in. The mean life span is 5-7 wk been buried for some time in soil require with 4-5 of this being required to reach exposure to light before germination can flowering (Sinha and Whitehead 1965): take pldce (Roberts and Lockett 1975). There are usually one or two generations per Baskin and Baskin (1976,1979) found that year but sometimes three (Salisbury 1964). high temperatures promote after-ripening Population density may be quite high and a and that a green "safe" light used with dark count of 668 chickweed plants/mz was controls was sufficient to stimulate germina- recorded in an area between potato and tion. However, the wavelength responsible barley crops on Westham Island in the Fraser for this stimulation may have been blue Delta. (400-500 nm) or yellow-orange (550-600 Chickweed is a pioneering species and nm) rather than the green (500-550 nm) per grows most rapidly in open areas. It is quick se. For emergence, the optimal depth of to colonize bare patches in fields and can burial is 1.0 cm and the maximum depth is grow at lower temperatures than most 2.0 cm (King 1966). grasses (Naber and Luten 1972). lt is, however, a poor competitor (Lawson 1972) (d) Vegetative reproduction Under suit- and is soon out-competed in growing able conditions, chickweed will- root at the swards, although it is persistent in grazed nodes of prostrate stems (Frankton and pastures (Schulz 1970). Chickweed may, Mulligan 1970). however, be a successful competitor when its mat-like growth form srnothers the 9. Hybrids seedlings of other species. Stace (1975) reported a hybrid berween S. Chickweed often exists as a solitary plant media and S . neglecta in Britain, but this has which may spread up to 1.5 m, or as small yet to be verified. Whitehead and Sinha patches in gardens. But, under suitable (1967) pointed out that the incidence of conditions it may form a continuous expanse crosses within different entities in the e.g. 80- 1007o cover in a2-habarley field on Stellaria media complex has lead to Westham Island, B.C. (Franko, unpub- taxonomic problems. lished). Peterson (1933, 1936) reported artificial intra- and interspecific crosses within the 11. Response to Herbicides and Other Stellaria media complex. The intraspecific Chemicals crosses had a very low rate of fertility. In The following information has been synth- most cases, interspecific crosses yielded no esized from information produced by the F1. However, S. media (2n:42\ x S. Canada Weed Committee (1977), the weed neglecta yielded sterile F, and, S. media control series of the B.C. Ministry of (?n:42) x S. neglecta vat. grandiflora Agriculture (Anonymous 1977), and the (2n:44) yielded an F, with 2n:43 (fertility Ontario Herbicide Committee ( I 978). of 64Vo\. Stellaria media is resistant tq foliar applications of 2,4-DB or MCPB, 10. Population Dynamics Bromoxynil + MCPA (l:l) and Dichlorop- The flowers of S. media are ephemeral and rop * 2,4-D ( l : l ). It is somewhat resistant to open only for I day (Salisbury 1974), during 2,4-D, 2,4,5-T and MCPA. The weed is daylight hours in bright weather (Grieve controlled by Fenoprop (l.2kglha), Mecop- 1959). It flowen and sets seed throughout rop (1.2 kelha), Dicamba (0.42 kelha), the year with two main flushes of Dicamba * Phenoxy (l:3 at 0.56 kg/ha), germination, early spring and late fall. It Linuron + MCPA (l:2 at 0.84 kg/ha), (L.) VLL. TTJRKINGTON ET AL. - STELLARIA MEDIA 989 Pronadime (0.84 kg/ha) and Chloroxuron 1962) andby grazing when grown with grass (5.6 ke/ha). (Schulz 1970).

12. Response to Other Human 13. Response to Parasites Manipulations Table I lists the parasites which are Close mowing controls chickweed associated with S. media in Canada and (Muenscher 1955) and the population of adjacent parts of the U.S.A. In all cases the viable seeds in the soil is greatly reduced mature plant is attacked. In other localities, after the second year of vegetable cropping Tomlinson and Walker (19'13) found tht (Roberts 196 . Roberts and Dawkins cucumber mosaic virus affects chickweed, (1967) reported a56Vo decrease in numbers giving the leaves a mottled appearance; but of chickweed seeds in areas ploughed four viral infections are often symptomless in times per year, compared to a 30% decrease chickweed (Converse and Stace-Smith in undisturbed plots. A June ploughing will l97l). Viral transmission is via pollen cause a IOOVo tncrease in the number of (Tomlinson and Carter 1970) or via seed summer seedlings. (Provvidenti 1975). The virus can also be Good drainage is an effective control ffansmitted by aphids from the chickweed to measure (Clark and Fletcher 1909). the crop plant (Provvidenti 1975). S. media is an effective competitor against Adam and Todd (1974) reported that cabbage seedlings, but an early spring chickweed is a host for the potato rot fungus weeding allows the cabbage to become (Phoma exigua var. foveata) and can established before the weed reestablishes transmit the fungus to a potato crop. (Lawson 1972\. Like most weeds, Viruses, fungi, aphids, and nematodes chickweed is favored by manuring (Robets often overwinter on chickweed plants and

Table | . Some of the parasites known to be associated with Stellaria media in Canada and adjacent parts of the U.S.A.

Viruses White clover mosaic virus British Columbia Conners 1967 Clover yellow mosaic virus British Columbia Toms 1964 Cucumber mosaic virus New York Prowidenti 1975 Tomato ring spot virus Vancouver, Washington Converse & Stace-Smith r97 | Turnip mosaic virus New Jersey Citir & Varney 1974 Beet curly-top virus Oregon smith 1972 Beet western yellows virus Oregon Smith 1972 Beet yellows virus All countries growing beets Smith 1972 Carnation mottle virus Wide range Smith 1972 Raspberry ring spot virus Wide range Smith 1972 Tomato black-ring virus Wide range Smith 1972 Fungi Septoria stellariae British Columbia Conners 1967, Toms Ro. & Desm. .19& Melampsorella B.C. and Ontario Conners 1967, Toms caryop hy I lac e arun Schroet. 1964 Puccinia arenariae Prince Edward Island Conners 1967 (Schum.) Wint. Insecta Myzus ascalonicus Canada Richards 1976 My zus ca ry o phy llac e arum Canada Richards 1976 Myzus persicae (Sulzer) New York Prowidenti 1975 990 CANADIAN JOURNAL OF PLANT SCIENCE are capable of infecting the crop plants sown BUCHANAN, G. A., HOVELAND, C. S. and the following season (Convefse and Stace- HARRIS, M. C. 1975. Response of weeds to soil Smith l97l). pH. Weed Sci. 23: 473-47'1 . Flore des alpes maritimes, Vol. Cooper and Harrison (1973) found that BURNAT. 1892. l. Genbve & Bale, Lyon. 302 pp. tobacco rattle virus infection in a potato field CANADA WEED COMMITTEE. 1975. Com- was dependent upon host preference of the mon and botanical names of weeds in Canada. vector nematodes (Trichodorus sp.). In- Can. Dep. Agric. Publ. 1937. Ottawa, Ont.67 pp. creased weeding of S. media served only to CANADA WEED COMMITTEE. 1977. Report increase the incidence of the virus on the of the Research Appraisal and Research Planning potato. The authors concluded that the Committee, Western Section, Edmonton, Alta. vector nematode prefers chickweed as a 109 pp. host, but will feed alternatively on the potato CARRUTHERS, W. 1903. Stellaria media'. is it crop when the chickweed is not available. poisonous? J. R. Agric . Soc . Engl. 64:296-309 . CASE, A. A. 1957. Some aspects of nitrate intoxication in livestock. J. Amer. Vet. Med. ACKNOWLEDGMENTS Assoc. 130:323. The authors are grateful for financial assistance CASPERS, N. 1977. Seasonal variations of from the National Reasearch Council of Canada caloric values in herbaceous plants. Oecologia and the YEPU program at the University of (Berl.) 26: 379-383. British Columbia. We also express our gratitude CHAMPNESS, S. S. and MORRIS, K. 1948. to herbaria personnel Agriculture Canada, at The population of buried viable seeds in respect Ottawa (W. Cody assistants), the J. and to contrasting pasture and soil types. J. Ecol. 36: (V. University of Saskatchewan, Saskatoon t49-173. Harms), the University of Alberta, Edmonton (J. ClTlR, A. and VARNEY. E. H. 1974. Common Packer), and the University of British Columbia, chickweed, a major weed host of turnip mosaic Vancouver (J. Pinder-Moss) who supplied much virus in New Jersey. Proc. Amer. Phytopathol. of the information on which Fig. 3 is based. We Soc. l: 134. are also grateful Dr. McNeil the to J. of CLARK, G. H. and FLETCHER, J. 1909. Farm Biosystematics Research Inst., Ottawa, Ontario weeds of Canada. 2nd ed. Agric. Canada, for valuable assistance concerning the authority Ottawa, Ont. 192 pp. to be ascribed to Stellaria media and to Leszlo CONNERS. l. L. 1967. An annotated index of Veto for taking the excellent S.E.M. photo- plant diseases in Canada and fungi recorded on graphs . Finally, we wish to thank Dr. J. Maze for plants in Alaska, Canada and Greenland. Can. valuable comments on the manuscript. Dep. Agric. Publ. 1251. Ottawa, Ont. 381 pp. CONVERSE, R. H. and STACE-SMITH, R. ADAM, J. W. and TODD, J. M. 1974. 1971. Rate of spread and effect of tomato Observations on the relative occurrences of ringspot virus on red raspberry in the field. Phoma exigua var. foveata on weed hosts and Phytopathology 61: I 104- I 106. potato€s. Potato Res. 17:347-350. COOPER, J. I. and HARRISON, B. D. 1973. ANONYMOUS. 1967. Seeds Act and Regula- The role of weed hosts and the distribution and tions. Agric. Canada. Queen's Printer, Ottawa, activity of vector nematodes in the ecology of Ont. 50 pp. tobacco rattle virus. Ann. Appl. Biol. 7 3: 53-66. ANONYMOUS. 1977. Field crop facts. Weed FEDEROV, A. A. 1974. Chromosome numbers control series. 2. Chickweed. British Columbia of flowering plants. Reprint by Otto Koeltz Min. of Agric. 3 pp. Science Pubs., Koenigstein, W. Germany.926 BASKIN, J. M. and BASKIN, C. C. 1976. High pp. temperature requirement for after-ripening in FERRON, M. and CAYOUETTE, R. 1975. seeds of winter annuals. New Phytol. 77: Noms des mauvaises herbes du Qu6bec. 3" ed. 619-624. Min. Agric. Colonisation , Qu6bec. l13 pp. BASKIN, J. M. and BASKIN, C. C. 1979. FRANKTON, C. and MULLIGAN, G. A. 1970. Promotion of germination of Stellaria media Weeds of Canada. Can. Dep. Agric. Publ. 948. seeds by light from a green safe lamp. New Canada Supply and Services, Ottawa, Ont.217 Phytol. 82: 38 I -383. pp. (L.) TURKINGTON ET AL. - STELLARIA MEDIA VLL 991 FRYER, J. D. and EVANS, S. A. (eds.) 1968. LOVE, A. and LOVE , D. 1975. Cytotaxonomi- Weed control handbook, vol. 2 Recommenda- cal atlas of the Arctic flora. Cramer, Vaduz. 598 tions. 5th ed. Blackwell, Oxford,- Gr. Br. 325 pp. pp. FRYER, J. D. and MAKEPEACE, R. J. 1977. MANN, H. H. and BARNES, T. W. 1950. The Weed control handbook, vol. I Principles. 7th competition between barley and certain weeds ed. Blackwell, Oxford, Gr. Br.- 510 pp. under controlled conditions. 4. Competition with GILBERT, B. E. and PEMBER, F. R. 1935. Stellaria media. Ann. Appl. Biol. 37: 139-148. Tolerance of certain weeds and grasses to toxic MATZKE. E. B. 1932. Flower variations and aluminum. Soil Sci. 39 425-429. symmetry patterns in Stellaria media and their GILKEY, H. M. 1957. Weeds of the Pacific underlying significance. Amer. J. Bot. 19: Northwest. Oregon State College, Portland, Ore. 477-507. 441 pp. MOORE, R. J. (ed.) 1973. Index to plant GRIEVE, M. 1959. A modern herbal, vol. l. chromosome numbers 1967-19'7 l. Utrecht, HafnerPubl., New York, N.Y. 427 pp. Netherlands, International Bureau for Plant GROH, H. and FRANKTON, C. 1946. Canadian and Nomenclature. 539 pp. weed survey fifth report. Agric. Canada, Ottawa, MOSS, C.E. 1914. The Cambridge British flora. Ont. 86 pp. vol. 3: Portulacaceae to Fumariaceae. Cambridge GROH, H. and FRANKTON, C. 1948. Canadian University Press, Cambridge, Gr. Br. 200 pp. weed survey seventh report. Agric. Canada, MUENSCHER, W. C. L. 1955. Weeds, 2nd ed. Ottawa, Ont. 144 pp. Macmillan, New York, N.Y. 560 pp. HATFIELD, A. W. 1970. How to enjoy your MULLIGAN, G. A. 1961. Chromosome num- weeds. FredrickMuller, London, Gr. Br. I l6pp. bers of Canadian weeds. 3. Can. J. Bot. 39: HEATHCOTE, G. D. and BYFORD, W. J. | 057- I 066. I 975 . Surveys of sugar-beet seed crops , mangold MULLIGAN, G. A. and FINDLAY, J. N. 1970. clamps and weeds in England for aphids and Reproductive systems and colonization in viruses, 1963-1973. J. Agric. Sci. 84: 87-95. Canadian weeds. Can. J. Bot. 48: 859-860. HITCHCOCK, C. L. and CRONQUIST, A. MULLIGAN, G. A. and KEVAN, P. G. 1973. 1973. Flora of the Pacific Northwest. Univ. of Color, brightness and other floral characteristics Washington Press, Seattle, Wash. 730 pp. attracting insects to the blossoms of some HULTEN, E. 1970. The circumpolar plantS. 2. Canadian weeds. Can. J. Bot. 51: 1939-1952. Dicotyledons. (cont'd. from Sv. Vet. Akad. MULLVERSTEDT, R. 1963. Untersuchungen Handl. Band. 8 Nr 5). Almquist and Wiksell, uber die Keimung von Unkrautsamen in Stockholm, Sweden. 275 pp. Abhangigkeit von Saverstoffpartialdruck. Weed. KING, L. J. 1966. Weeds of the world; biology Res.3: 154-163. and control. Plant Sci. Monogr. Intersci. Publ. NABER, H. and LUFTEN, W. 1972. Chickweed Inc., New York, N.Y. 526 pp. in grassland and its control. Bedrijfson Wikkel- KNUTH, P. 1908 Handbook of flower pollina- ing 3: 9l l-913. tion. Vol.2. Rananculaceae to Stylidieae. ONTARIO HERBICIDE COMMITTEE. 1978. Clarendon Press, Oxford, Gr. Br. 703 pp. Guide to chemical weed control. Min. of Agric. KRAFT, E. 1917. Experimentelle und entwic- and Food, Toronto, Ont. Publ. 75, 103 pp. kelungsgeschichtliche Untersuchungen an O'LEARY, T. E. 1973. Broad-leaved weed Caryophyllaceen Bliiten. Flora 109 : 283 -3 56. infestations in cereals. Agric. Tech., Spring, LAWSON, H. M.- 1972. Weed competition in 37-41. Fisons, Agrotechnical Div., Harston, transplanted spring cabbage. Weed Res. 12: Cambridge, Gr. Br. 254-267. PEDERSEN, A. 1972. Adventitious plants and LEFEVRE, P. 1956. Influence de milieu et des cultivated plants in Greenland. Meddelelser om conditions d'exploration sur le d6veloppement Grpnland. 178. (7). 98pp. des plantes adventices. Effet particulier du pH et PETERSON, D. 1933. Stellaria media L. x l'6tat calcique. Ann. Agron. Paris 7: 299-347 . Stellaria neglecta Weihe. Bot. Notiser. pp. LONG, H. C. 1938. Weeds of arable land. Bull. 500-504. 108. Min. Agric. and Fish.. London. Gr. Br. 2l5 PETERSON, D. 1936. Stellaria-Studien. Zur pp. Zytologie, Genetik, Okologie und Systematik der LOUSLEY, J. E. 197 |. The flora of the isles of Gattung Stellaria, insbesondere der media- Scilly. Redwood Press, London. 336 pp. Gruppe. Bot. Notiser. pp. 281-419. 992 CANADIAN JOURNAL OF PLANT SCIENCE

PROCTOR, M. and YEO, P. 1973. The SPENCER. E. R. 1940. Just weeds. Scribner, pollination of flowers. Collins, London, Gr. Br. New York, N.Y. 317 pp. 481 pp. STACE, C. A. 1975. Hybridization and the flora PROVVIDENTI. R. 1975. Natural infection of of the British Isles. Academic Press, London, Gr. Celosia argenta by cucumber mosaic virus in a Br. 626 pp. commercial greenhouse. Plant Dis. Rep. 59: STALDER, L., POI-IER, C. A. and BARBEN,

1 66- 1 68. E. 19'73 . New herbological aspects in viticulture: REINOHL. F. 1903. Die Variation im An- weed control or management? Schweiz. Z. Obst. droecium der Stellaria media Cyr. Bot. Zeit. 6l: Weinbau 1)9:246-261 . I 59-200. TAYLOR, R. L. and MACBRYDE, B. 197-7. RICHARDS. W. R. 1976. A host index for Vascular plants of British Columbia: A descrip- species of Aphidoidea described during 1935 to tive resource inventory. Tech. Bull. No. 4, The 1969. Can. Entomol. 108:499-550. Botanical Garden, IJniversity of British Colum- ROBERTS, H. A. 1962. Studies on the weeds of bia. University of B.C. Press, Vancouver, B.C. vegetable crops. 2. Effect of six years of cropping 754 pp. on the weed seeds in the soil. J. Ecol. 50: TAYLOR, R. L. and MULLIGAN, G. A. 1968. 803-8 I 3. Ffora of the Queen Charlotte Islands. Part 2. ROBERTS, H. A. 1964. Emergence and Cytological aspects of the vascular plants. longevity in cultivated soil of seeds of some Queen's Printers, Ottawa, Ont. 148 pp. annual weeds. Weed. Res. 4:296-307. TOMLINSON, J. A. and CARTER,-A. L. 1970. ROBERTS, H. A. and DAWKINS, P. A. 1967. Studies on the seed transmission of cucumber Effect of cultivation on the numbers of viable mosaic virus in chickweed (Stellaria media) in weed seeds in soil. Weed Res. 7: 290-301. relation to the ecology of the virus. Ann. Appl. ROBERTS, H. A. and LOCKETT, P. M. 1975. Biol.66:381-386. Germination of buried and dry-stored seeds of TOMLINSON, J. A. and WALKER, V. M. Stelleria media. Weed Res. 15: 199-204. 1973. Further studies on seed transmission in the ROUSSEAU, C. 1968. Histoire, habitat et ecology of some aphid-transmitted viruses. Ann. distribution de 220 plantes introduites au Qu6bec. Appl. Biol. 73: 293-298. Natur. Can. 95: 49-17l. TOMS, H. N. 1964. Plant diseases of Southern SALISBURY, E. J. 1964. Weeds and aliens. British Columbia A host index. Can. Plant Collins, London, Gr. Br. 38a pp. Dis. Surv. 4(3): 143-225.- Res. Br., Can. Dep. SALISBURY, E. J. 1974. The variation in the Agric., Ottawa, Ont. reproductive organs of Stellaria media (sensu TOOLE, E. H. and BROWN, E. 1946. Final stricto) and allied species with special regard to results of the Duvel buried seed experiment. 'J. their relative frequency and prevalent modes of Agric. Res. 72: 2Ol-210. pollination. Proc. R. Soc., London, Ser. B. 185: WALKEY, D. G. A. and COOPER, E . I. 1976. 331-342. Growth of Stellaria media, Capsella bursa' SCHULZ, H. 1970. The effect of differential pastoris, and Senecio vulgaris plantlets from cropping on the plant composition, yield, and cultivated meristem tips. Plant Sci. Lett. 7: chemical contents of two permanent grassland r79-186. areas. Z. Acker. Pflanz. 1.3l: 233-250. WALTON, D. W. H. 1975. European weeds and SINHA, R. P. and WHITEHEAD, F. H. 1965. other alien species in the subantarctic. Weed Res. Meiotic studies of British populations of Stellaria 15:271-282. media (L.) Vill., S. neglecta Weihe and S. WHITEHEAD, F. H. and SINHA, R. P. 1967. pallida (Dumort.) Pir6. New Phytol. 64: Taxonomy and taximetrics of Stellaria media 343-345. (L.) Vill., S. neglecta Weihe and S. pallida SMITH, K. M. 19'12. A textbook of plant virus (Dumort.) Pir6. New Phytol. 66:769-784. diseases. 3rd ed. Longman, l-ondon, Gr. Br. 684 pp.