Reproductive systems and colonization in Canadian weeds

Mulligan, Gerald A.; Findlay, Judy N.

doi:10.1139/b70-119

Cited by 97 publications

(60 citation statements)

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“…Conyza canadensis is selfcompatible (Mulligan and Findlay 1970). Pollen is released before the capitula have fully opened, suggesting that it is primarily self-pollinating, although insects have been observed visiting open flowers (Smisek 1995).…”

Section: Reproductionmentioning

confidence: 99%

The biology of Canadian weeds. 115. Conyza canadensis

Weaver¹

2001

Can. J. Plant Sci.

243

291

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Weaver, S. E. 2001. The biology of Canadian weeds. 115. Conyza canadensis Can. J. Plant Sci. 81: 867-875. Conyza canadensis (L.) Cronq. (Canada fleabane, horseweed, mare's-tail) is a winter or summer annual, native to North America, and found in all provinces of Canada except Newfoundland. It is a weed of orchards, vineyards, roadsides, and arable fields where tillage has been reduced or eliminated. Most seedlings emerge from late August through October and form rosettes which overwinter. Large numbers of small, wind-dispersed seeds, ranging to over 200 000 seeds per plant, are produced in late summer. Populations of C. canadensis in more than ten countries have evolved resistance to herbicides such as paraquat, atrazine, chlorsulfuron or glyphosate. Several paraquat resistant populations were found in orchards in Essex Country, Ontario. It serves as a wild host of the tarnished plant bug, and of aster yellows, a mycoplasma disease transmitted by the aster leaf hopper. On la trouve dans toutes les provinces du Canada sauf Terre-Neuve. Elle envahit les vergers, les vignobles, les bords de route et les terres arables dont on ne travaille plus le sol, ou très peu. La plupart des plantules apparaissent de la fin du mois d'août à octobre et forment des rosettes qui hiverneront. La plante produit au-delà de 200 000 petites graines qui seront dispersées par le vent à la fin de l'été. Dans plus de dix pays, les peuplements de C. canadensis ont acquis une résistance à divers désherbants tels le paraquat, l'atrazine, le chlorsulfuron et le glyphosate. Plusieurs peuplements résistants au paraquat ont été découverts dans des vergers du comté d'Essex, en Ontario. La vergerette du Canada est l'hôte sauvage de la punaise grise et de la jaunisse de l'aster, mycoplasme transmis par la cicadelle de l'aster. Description and Account of Variation(a) Winter or summer annual, reproducing only by seeds; short taproot with laterals; seedlings form a basal rosette of dark green, sparsely hairy leaves, rarely more than 1 cm wide, with distinct petioles and coarsely toothed margins; the basal rosette deteriorates after the stem begins to elongate; stems are erect, 10-180 cm high, hairy, with many small flowering branches in the upper portions; stem leaves alternate, numerous and crowded on the stem, often appearing opposite or even whorled, lanceolate to linear, with nearly entire margins; upper stem leaves only 5 mm wide; flower heads (capitula) small, 3-5 mm in diameter, and numerous on short branches near the top of the main stem; pistillate ray florets are white, ligulate and very short, often concealed by involucre bracts around each head; perfect disk florets are yellowish-green and very fluffy at maturity; seeds (achenes), averaging 60-70 per capitulum, are small, 1-2 mm long, transparent and have an attached pappus 3-5 mm in length (Frankton and Mulligan 1987;Alex 1992).Conyza canadensis is a diploid species, with a chromosome number of 2n = 18 for Canadian and other specimens (Mulligan 1957; Federov 1969;Thebaud and Abbott 1995)....

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Section: Reproductionmentioning

confidence: 99%

The biology of Canadian weeds. 115. Conyza canadensis

Weaver¹

2001

Can. J. Plant Sci.

243

291

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“…data (Waddington 1976). The flowers are visited by halictid bees, honeybees, bumblebees, butterflies and moths (Mulligan 1972' 1973; Waddington 19'76)-Plants of C. arvensis examined in Ontario were selfincompatible (Mulligan and Findlay 1970 Seeds of C. arvensis will remain viable in the soil for 20 yr or more (Timmons 1949 to 26 Sept. germinated and produced seedlings at each planting (Brown and Porter 1942). Emergence was greatest in the spring (60-75Vo) and late summer and least in midsummer (1-107o).…”

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THE BIOLOGY OF CANADIAN WEEDS.: 53. Convolvulus arvensis L.

Weaver¹,

Riley²

1982

Can. J. Plant Sci.

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Convolvulus arvensis L., field bindweed, is an introduced weed which occurs in the agricultural regions of all provinces of Canada with the exception of Newfoundland and Prince Edward Island. Its twining growth habit and extensive root and rhizome system make it exceptionally difficult to control. It spreads by both seeds and root or rhizome fragments. Details of its morphology, reproductive biology, response to parasites, and methods of control are presented.

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“…Descriprion and Account of Yariation (a) Both species can be described as annual, biennial, or perennial herbs (Tessene 1968;Mulligan and Findlay 1970;Bassett \973) each with a fibrous, adventitious root system arising from a stout caudex that bears a rosette of spirally arranged leaves. The following descriptions have been taken from Tessene (1968) and Bassett (1973)…”

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THE BIOLOGY OF CANADIAN WEEDS. 4. PLANTAGO MAJOR AND P. RUGELII

Hawthorn¹

1974

Can. J. Plant Sci.

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Reproductive systems and colonization in Canadian weeds

Cited by 97 publications

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The biology of Canadian weeds. 115. Conyza canadensis

The biology of Canadian weeds. 115. Conyza canadensis

THE BIOLOGY OF CANADIAN WEEDS.: 53. Convolvulus arvensis L.

THE BIOLOGY OF CANADIAN WEEDS. 4. PLANTAGO MAJOR AND P. RUGELII

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