Weedy mustards, Brassicaceae (Cruciferae) of Canada

  (slightly modified from Mulligan, Gerald A. 2002. Weedy mustards (Brassicacea) of Canada.
Canadian Field-Naturalist 116: 623-631)

WeedsPoisonous PlantsHay Fever
Gerald A. Mulligan (Agriculture Canada, Ottawa, retired)
      Our weeds are plants that are preprogrammed to colonize the many open and disturbed habitats created and maintained by deforestation, agriculture, settlements, and a network of railway lines and roads. Some of these weedy colonizers are native plants that previously only occurred in naturally disturbed habitats, but the most aggressive are introduced plants that have evolved as the result of a long association with human activities in the Old World. In addition, many of these introduced colonizers have left their competitors, pests, and parasites behind. Some of the most successful weedy colonizers in Canada are plants of the mustard family (Brassicaceae). A few of these, such as bird rape (Brassica rapa L.) and wild and cultivated radishes (Raphanus species), have even evolved both weedy and cultivated strains during their long association with humans. The most successful colonizing mustards are generally autogamous (produce abundant seed by self-fertilization within the same plant), apomictic (produce abundant seed without the ovaries being fertilized), or have either a strong vegetative means of reproduction or are common contaminants in crop seed. Colonization by weeds is, in fact, completely dependent on the availability of the many disturbed habitats that we have created and continue to maintain. Humans are, in fact, mainly responsible for creating and maintaining the habitats that are necessary for the survival of the very plants that we are most anxious to control or eliminate.
      This paper provides a listing of the weedy mustards of Canada, and information on their origin, introduction, spread, distribution, abundance, and habitats. Included are the chromosome numbers that have been determined from Canadian material. Much of the information included here has resulted from data obtained during two of my recent studies: Key to the Brassicaceae (Cruciferae) of Canada and Alaska (Mulligan unpublished) and Chromosome numbers determined from Canadian and Alaskan material of native and naturalized Brassicaceae (Cruciferae), (Mulligan 2002).


Abbreviations

AK: Alaska
YT: Yukon
NT-M: Northwest Territories- Mackenzie District
N-K: Nunavut- Keewatin District
N-F: Nunavut- Franklin District
NF: Newfoundland and Labrador
PE: Prince Edward Island
NS: Nova Scotia
NB: New Brunswick
PQ: Québec
ON: Ontario
MB: Manitoba
SK: Saskatchewan
AB: Alberta
BC: British Columbia


Systematic List

Alliaria petiolata (M.Bieb.) Cavara & Grande ( = Alliaria officinalis Andrz. ex M. Bieb.) -garlic mustard; alliaire officinale
 Self incompatible biennial. Introduced from Europe for use as a medicinal and salad plant. First collected at Moss Park, Toronto, ON, by J. Fletcher in 1874. Shaded and semi-shaded habitats in NB, PQ, ON, and BC; sporadic except in southern ON. Disagreeable flavor in milk from cows eating garlic mustard.
See Cavers et al. (1979). 2n = 42, ON (Mulligan 1984).

Alyssum alyssoides (L.) L. -small alyssum; alysson à calices persistants
 Self-compatible, autogamous, annual or winter annual, introduced from Eurasia. First collected by W. Scott at Lincoln, ON, in 1896. Roadsides, railway beds, waste places, ballast, and other disturbed habitats in NF, PQ, ON, MB, AB, and BC; most common in southern ON and southeastern BC. 2n = 32 (Mulligan 1964).

Alyssum desertorum Stapf -yellow alyssum; alysson de déserts
 Self-compatible, autogamous, annual, introduced from eastern Europe and western Asia. First collected on a railroad grade at Mortlack, SK, by J. H. Hudson in 1955. Prairie, grain elevators, railway beds, roadsides, and waste places in southern SK, southern AB, and southeastern and southcentral BC. Abundant on sheep rangelands in Rocky Mountain and Great Basin regions of the United States (Rollins 1981). 2n= 32, AB (Mulligan 1964).

Alyssum murale Waldst. & Kit. -yellow-tuft
 Caespitose perennial. Ornamental, native of Europe, that is a rare escape from cultivation or persists at old garden sites in PQ, ON, AB, and BC. First collected at Lambton, ON, by H. N. Racicot in 1947.

Alyssum saxitale L. -golden-tuft
 Perennial, introduced from Europe. Frequently grown as an ornamental. The only specimen seen was collected in waste ground at Ste-Anne-de-la-Pocatière, PQ, by L. Cinq-Mars in 1967. It may not persist in nature.

Arabidopsis thaliana (L.) Heynh. -mouse-ear- cress; arabette des dames
 Self-compatible, autogamous, annual, introduced from Eurasia. First collected by H. Groh at Agassiz, BC, in 1931. Sporadic in gardens, roadsides, railway beds, and waste places in southern PQ, southern ON, and southern BC. Used extensively in experimental biology. 2n = 10, ON (Mulligan 1984).

Arabis caucasica Willd. -wall rock-cress; corbeille d’argent
 Self-incompatible, perennial, rock garden plant. Native of Eurasia. First collected by A. Hamel and A. Payette, in tidal debris, at Rivière-du-Loups, PQ, in 1949. Rare garden escape along a roadside in YT, and in cliff faces, tidal rocks, and tidal debris in NB, PQ, and ON. 2n = 16, ON (Mulligan 1964).

Arabis glabra (L.) Bernh. ( =Turritis glabra L.) -tower mustard; arabette glabre
 Self-compatible, autogamous, biennial. Both native and introduced from Eurasia. First collected in a sandy field at London, ON, by T. W. Burgess, in 1879. Native on dry slopes in the Cypress Hills of SK and AB, and in the mountainous regions of southwestern AB and southern BC. Probably introduced into YT, NT-M, NB, PQ, ON, MB, SK, AB, and BC. Naturalized in sandy roadsides, waste places and field margins throughout its range. 2n = 12, PQ, ON, AB, and BC (Mulligan 1964; Taylor and Mulligan 1968; Mosquin in Mulligan 1995).

Arabis hirsuta (L.) Scop. var. hirsuta -hairy arabis; arabette hirsute
 Biennial or short-lived perennial, native of Europe. The only Canadian specimens were collected by E. Haber and M. J. Schepanek along a roadside in a campground in Glacier National Park, BC, on July 29, 1972, and by V. L. Harms, south of Swift Current Bay of Diefenbaker Lake, SK, on July 21, 1966. Probably introduced from populations known to occur in the United States.

Armoracia rusticana P. Gaertn., B. Mey. & Scherb. -horseradish; raifort
 Self-incompatible perennial, introduced from Europe. Thick, deep, branching, woody roots used as source of sauce or relish. Naturalized in PQ as early as 1850 (Rousseau 1968). Roadsides, ditches, waste places, and old garden sites. Sporadic in PE, and from NB to BC. Once established, difficult to eradicate.

Barbarea stricta Andrz. -small flowered winter cress; barbarée raide
 Perennial, introduced from Europe. First collected at Gross-Ile, PQ, in St. Lawrence River, in 1944, by R. P. Hanson (Mulligan 1978). Jacques Cayouette has recently seen it at several locations on the island. He also collected it in Comté de Duplessis and Comté de Montmagny, in PQ, in 1979 (Cayouette 1984). It was reported to be at Temagami Forest Reserve, ON (Dorofeev 1998). May be more common than realized because of its confusion with the “typical” phase of Barbarea vulgaris and with Barbarea orthoceras.

Barbarea verna (Mill.) Aschers. -early winter cress; barbarie printanière
 Biennial or short-lived perennial, introduced from Europe as a salad plant. First collected at St. Pierre, NF, by L. Arsène in 1900. Roadsides and waste places in NF and on Vancouver Island, BC.

Barbarea vulgaris (L.) W. T. Aiton -yellow rocket; barbarée vulgaire
 Self-incompatible perennial, introduced from Europe, probably as a common impurity in clover, alfalfa, and grass seed. Reproduces both by seed and cauline rosettes. First reported at Montreal in 1821 (Rousseau 1968). NF, PE, NS, NB, PQ, ON, MB, AB, and BC; mostly in non-cultivated fields, roadsides, and waste places. Sometimes used as salad or garnishing plant. See MacDonald and Cavers (1991). 2n = 16, ON (Mulligan 1959, 1984).

Berteroa incana (L.) DC. -hoary alyssum; bertéroa blanc
 Annual or winter annual, introduced from Europe. First collected at Wallbridge, ON, by Massey in 1893. Sporadic, but often locally abundant in NS, NB, PQ, ON, MB, SK, and BC. Non-cultivated fields, roadsides, waste places, and settlements; often on poorer soils. 2n = 16, ON (Mulligan 1957).

Brassica juncea (L.) Czern. -Indian mustard; moutarde d’Inde
 Annual, introduced from Europe as a seed contaminant. Often cultivated for greens. Present in PQ in 1875 (Rousseau 1968) and was collected in a potato field, at Winnipeg, MB, by J. Fletcher in 1896. Cultivated fields, roadsides, and waste places in all provinces from NF to BC. Reaches greatest abundance in Prairie Provinces. 2n = 36, AB (Mulligan 1959).

Brassica napus L. -rape; navet
 Annual, introduced from Eurasia. Sporadic escape from cultivation. First collected at St. John, NB, by G. F. Matthew in 1874. Rare plant in cultivated and abandoned fields, roadsides, railways, and waste places in NT-M and every province from NF to BC.

Brassica nigra (L.) W. D. J. Koch -black mustard; moutarde noire
 Annual, introduced from Europe. An escape from cultivation and a seed contaminant. Naturalized in Canada since 1863 (Groh and Frankton 1946). Sporadic in cultivated fields, gardens, waste places, and roadsides in NF, NS, NB, PQ, ON, AB, and BC.

Brassica oleraceae L. -a great number of agricultural and horticultural varieties
 Annual, introduced from Eurasia. Many cultivated varieties escape from cultivation but do not persist in Canada.

Brassica rapa L. ( = Brassica campestris L.) -bird rape; moutarde des oiseaux
 Annual or winter annual, introduced from Eurasia. Has oil seed, vegetable, salad plant, and weed phases. Mostly introduced into fields as a contaminant in crop seed. In NS as early as 1829 (Rousseau 1968). Cultivated fields, roadsides, and waste places in YT, NT-M, and in all provinces from NF to BC. Most common in the Maritime Provinces, maritime areas of PQ, and the Fraser Valley and Vancouver Island of BC. 2n = 20, ON and BC (Mulligan 1959; Taylor and Mulligan 1968).

Bunias orientalis L. -Turkish rocket; bunias d’Orient
 Perennial, introduced from Eurasia. Very sporadic in waste land and along roadsides in NS, NB, southern PQ, and southern BC. Does not persist except at a few locations on Vancouver Island and in the Fraser Valley of BC. Collected at Botanie, BC, by W. B. Anderson in 1927 and at the same site by F. Lomer in 1995.

Cakile edentula (Bigelow) Hook. var. edentula -sea rocket; caquillier édentulé
 Annual coastal strand herb, native to east coast but introduced on the west coast. In NF, PE, NS, NB, PQ, and BC. 2n = 18, PQ and BC (Mulligan 1964; Taylor and Mulligan 1968).

Cakile maritima Scop. -sea rocket; caquillier maritime
 Annual seashore strand herb, introduced from Europe. West coast, from Queen Charlotte Islands, BC, to Baja, California. Sporadic along east and Gulf coasts of the United States (Rollins 1981).

Camelina alyssum (Mill.) Thell. ( =Camelina parodii Ibarra & La Porte) -flat-seeded false flax; caméline alysson
 Annual, introduced from Europe as an impurity in crop seed. First collected at Middle Lake, SK, by W. W. Robins in 1910. Infrequent in cultivated fields, roadsides and waste places in the southern parts of MB, SK, and AB.

Camelina microcarpa Andrz. ex DC. -small-seeded false flax; caméline à petits fruits
 Self-compatible, autogamous, annual, introduced from Eurasia. Contaminant in flax and grain seed. First collected at Snelgrove, ON, by J. White in 1897. In all provinces, but most common in the Prairie Provinces. Open prairie, cultivated fields, roadsides, railway beds, and waste places. 2n = 40, AB and BC (Mulligan 1957, 1984).

Camelina sativa (L.) Crantz -large-seeded false flax; caméline cultivée
 Self-compatible, autogamous, annual, introduced from Eurasia. Contaminant in flax and grain seed. First collected at Fish Creek, AB, by J. Fowler in 1894. In YT(rare), NT-M, and from PQ to BC. Less common than small-seeded false flax. Prairies, cultivated fields, around grain elevators, roadsides, railways, and waste places. 2n = 40, AB and BC (R. J. Moore, unpublished).

Capsella bursa-pastoris (L.) Medik. -shepherd’s purse; bourse-à-pasteur
 Autogamous, self-compatible, annual or winter annual, introduced from Europe. Recorded in New England as early as 1672 (Rousseau 1968) and in Nova Scotia as early as 1829 (Groh 1945). In YT, NT-M, N-F, and all provinces from NF to BC. Common plant in cultivated fields, pastures, meadows, roadsides, railway beds, and waste places, in all settled areas of Canada. 2n = 32, ON, SK and BC (Mulligan 1957,1984, Taylor and Mulligan 1968).

Cardamine flexuosa With. -wavy bitter cress; cardamine flexueuse
 Biennial or short-lived perennial, introduced from Europe. First collected in a park at St. John’s, NF, by A. M. Ayre in 1927. Rare in wet springy banks and thickets in NF.

Cardamine hirsuta L. -hoary bitter cress; cardamine hirsute
 Autogamous, self-compatible, annual, introduced from Europe. First collected at Vancouver, BC, by J. R. Anderson in 1896. Rare in ON, and common on Vancouver Island and in the Fraser Valley of BC. Old fields, gardens, ditches, roadsides, and waste places, usually in moist soil. 2n = 16, BC (Mulligan 1965).

Cardamine impatiens L. -narrow leaved bitter cress; cardamine impatiente
 Annual or biennial herb introduced from Europe. Only specimen seen was collected from a deciduous woods, on St. Lawrence Starch Works property, Port Credit, ON, by J. M. Weber in 1980. It is sporadic and uncommon in the United States (Rollins 1981).

Cardamine pratensis L. -cuckoo flower; cardamine des prés
 Perennial. In YT, NT-M, N-K, N-F, NS, and from NB to BC. Plants in southern part of its range are mostly rare ornamental escapes of Eurasiatic origin. Plants in the northern part of its range, in Canada, are`probably native.

Cardaria chalepensis (L.) Hand.-Mazz. -lens-podded hoary cress; cranson rampant
 Strongly rhizomatous perennial, introduced into Canada and the United States in alfalfa seed imported from Turkestan about 1911 or 1912. First collected in the United States at Fargo, North Dakota, in 1912, and in Canada at Grande Prairie, AB, in 1926. In cultivated and non-cultivated habitats from ON to BC. Most abundant in irrigated areas of western Canada and the western United States. The three hoary cresses, found in Canada, now survive and spread primarily by extremely persistent vertical and horizontal roots. This is the most aggressive of the three hoary cresses. Fields, ditches, roadsides, pastures, and waste places; often on saline soils. See Mulligan and Findlay (1974). 2n = 80, SK, AB and BC (Mulligan and Frankton 1962).

Cardaria draba (L.) Desv. -heart-podded hoary cress; cranson dravier
 Rhizomatous perennial, introduced from Europe and Western Asia. First collected in the United States at Long Island, New York, in 1862, and in Canada at Barrie, ON, in 1878. Present in NS, and from ON to BC. It is most troublesome in southern MB and southern AB. Cultivated fields, hayfields, pastures, irrigation ditches, roadsides, and waste places. Least weedy of the hoary cresses. See Mulligan and Findlay (1974). 2n = 64, AB (Mulligan and Frankton 1962).

Cardaria pubescens (C.A.Mey.) Jarmol. -globe-podded hoary cress; cranson velu
 Rhizomatous perennial introduced into Canada and the United States in alfalfa seed imported from Turkestan in 1911 or 1912. In MB, SK, AB, and BC. Often found in the same fields as lens-podded hoary cress, but not nearly as aggressive. First collected in the United States at Fargo, North Dakota, in 1912, and in Canada at Grande Prairie, AB, in 1926. In cultivated and non-cultivated fields, especially in irrigated areas where saline soils are present. See Mulligan and Findlay (1974). 2n = 16, SK and AB (Mulligan and Frankton 1962).

Chorispora tenella (Pallas) DC. -blue mustard; chorispora fluet
 Annual or winter annual, introduced from Asia. First collected at Penticton, BC, by J. W. Eastham in 1940. Very rare and often not persisting. In the southern parts of SK, AB, and BC. Very abundant in rangelands of the United States (Rollins 1981).

Conringia orientalis (L.) Dumort. -hares’s-ear mustard; vélar d’Orient
 Autogamous annual or winter annual, introduced from Eurasia. First collected at Bass River, NB, by J. Fowler in 1872. In all provinces from NF to BC. Reaches greatest abundance in the Prairie Provinces, especially SK. Grain fields, disturbed prairie, pastures, roadsides, railways, and waste places.

Coronopus didymus (L.) Sm. -lesser swine cress; corne-de-cerf didyme
 Annual or winter annual, introduced from Asia or South America. First collected on a wharf at Gaspé Basin, PQ, by J. Bell in 1862 and at North Sidney, NS, by T. W. Burgess in 1883. Rare in ballast, roadsides, waste places, and in old fields along the coasts of NF, NS, NB, PQ, and southern BC.

Coronopus squamatus (Forssk.) Asch. -creeping wart cress; corne-de-cerf écailleuse
 Biennial or short-lived perennial, introduced from Europe. First collected on a wharf at Gaspé Basin, PQ, by J. Bell in 1862 and at St. John, NB, by J. Fowler in 1877. Rare in coastal areas of NS, NB, and PQ, and on lake shores in ON.

Descurainia sophia (L.) Webb. -flixweed; sagesse-des-chirurgiens
 Autogamous, self-compatible, annual or winter annual, introduced from Eurasia. At Montreal, PQ, in 1821; probably reaching Canada with early French settlers (Rousseau 1968). First collected , in the prairies, at Plum Coulee, MB, by J. Fletcher in 1907, and at Antler, SK, by E. L. Stonehouse in the same year. In YT, NT-M, and from PE to BC. Most common in the Prairie Provinces, especially in cereal crops. Sporadic elsewhere. In disturbed grasslands, hay fields, grain fields, roadsides, and waste places. See Best (1977). 2n= 28, SK, AB and BC (Mulligan 1961b, 1984; Taylor and Mulligan 1968).

Diplotaxis erucoides (L.) DC. -white rocket; diplotaxe fausse-roquette
 Annual or winter annual, native of Europe. In Canada, only known from PQ; Gaspé-Nord in 1904 and Laval in 1961 (Rousseau 1968). On ballast in New York City and in Camden, New Jersey, prior to 1880 (Rollins 1981). Very rare plant on ballast and in waste places. May not persist.

Diplotaxis muralis (L.) DC. -sandrocket; diplotaxe des murs
 Autogamous, annual or winter annual, introduced from Europe. First collected on ship ballast at North Sydney, NS, and at Pictou, NS, by J. Macoun in 1883. Sporadic, but locally abundant, from PE to AB. In disturbed grasslands, gardens, railway beds, and waste places, and around buildings.

Diplotaxis tenuifolia (L.) DC. -wall-rocket; diplotaxe à feuilles ténues
 Perennial, introduced from Europe. First collected at St. John, NB, by J. Fowler in 1877. NS, NB, PQ, ON, and BC. Most common in southern ON; sporadic elsewhere. In waste places, ballast, railway beds, and along roadsides. 2n = 22, ON (Mulligan 1959).

Draba nemorosa L. -wood whitlow-grass; drave des bois
 Native, autogamous, annual or winter annual. In YT, NT-M, PQ, and from PQ to BC. Introduced in Eastern Canada and native elsewhere. Has colonized a wide variety of artificially disturbed habitats both within and outside of its native range. 2n = 16, ON, MB and AB (Mulligan 1966, 1975; Packer 1964; Löve and Löve 1982).

Draba verna L. -whitlow-grass; drave printanière
 Autogamous, annual or winter annual, introduced from Europe. First collected at Quebec, PQ, by J. Bell in 1865. NB, and southern parts of PQ, ON, AB, and BC. In disturbed grasslands, railway beds, roadsides, and waste places, especially on light soils. 2n = 39, BC (Mulligan 1966).

Eruca vesicaria (L.) Cav. subsp. sativa (Mill.) Thell. -garden-rocket; roquette des jardins
 Annual, introduced from Eurasia. Grown for salad purposes. First collected at Grenfell, SK, by Deacon in 1908. Early introductions were from contaminants in alfalfa seed (Groh 1944). Sporadic in waste places, cultivated fields, and roadsides in PQ, and southern parts of ON, SK, AB, and BC.

Erucastrum gallicum (Willd.) O. E. Schulz -dog mustard; moutarde des chiens
 Autogamous annual or winter annual, introduced from Eurasia. First collected at Emerson, MB, by H. Groh in 1943. Early collections were along railway beds, near grain elevators, and at grain shipping terminals. In cultivated fields, roadsides, railway beds, and waste places in NT-M, and from NF to BC. See Warwick and Wall (1998). 2n = 30, ON (Mulligan 1957, 1984).

Erysimum cheiri (L.) Crantz -common wallflower
 Perennial, introduced from Europe, grown as an ornamental. An infrequent garden escape near Whitehorse, YT, at Ste-Foy, PQ, and on southeast Vancouver Island, B.C.

Erysimum cheiranthoides L. -wormseed mustard; vélar fausse-giroflée
 Autogamous annual or winter annual, introduced from Eurasia. First recorded in the United States , in Virginia, by Pursh in 1814 and, in Canada, by Hooker in 1830 (Rousseau 1968). Present in YT, NT-M, and in all provinces from NF to BC. In a wide range of disturbed habitats , but it is usually sparse at any single location. 2n = 16, ON and BC (Mulligan 1957, 1984; Taylor and Mulligan 1968).

Erysimum hieraciifolium L. -tall wormseed mustard; vélar à feuilles d’epérvière
 Apomictic biennial or short-lived perennial, introduced from Europe. First seen at Ottawa, ON, in 1941 and collected at Apple Hill, ON, by E. G. Anderson in 1946. In NS, NB, PQ, ON, and SK. Reaches greatest abundance, and is spreading rapidly, in roadsides, gravel pits, pastures, and hay fields in eastern ON. 2n= 48, meiosis irregular, ON (Mulligan and Frankton 1967).

Erysimum repandum L. -treacle mustard; vélar étale
 Annual or winter annual, introduced from Eurasia. First collected on Pelee Island, ON, by W. Botham in 1938. A rare mustard, present only at a few sites in waste places, railway beds, and roadsides in Essex and Kent Counties in southern ON, and in the Fraser Valley of BC.

Hesperis matronalis L. -dame’s rocket; julienne des dames
 Perennial, introduced from Europe as an ornamental plant. Naturalized in PQ as early as 1862 (Rousseau 1968). Sporadic in old garden sites, roadsides, and waste places in all provinces. 2n = 24, ON (Mulligan 1984).

Hutchinsia procumbens (L.) Desv. ( =Horungia procumbens (L.) Hayek) -oval shepherd’s purse; hutchinsie couchée
 Annual herb, introduced from Eurasia. First collected at Cache Creek, BC, by J. Macoun in 1875. Occurs at a few sites, on moist alkaline flats and seashores, in NF, MB, southern SK, and southern BC.

Iberis amara L. -rocket candytuff; iberis amer
 Annual, introduced from Europe as an ornamental. First collected at Lindsay, ON, in 1903 by W. Scott. A rare escape, in roadsides and waste places, in NS, and ON.

Iberis umbellata L. -globe candytuff; iberis à ombelles
 Annual, introduced from Europe as an ornamental. A rare escape from cultivation that is sometimes found in roadsides and waste places in PE, NS, and PQ.

Isatis tinctoria L. -dyers woad; pastel des teinturiers
 Biennial, formerly cultivated for its blue dye. Sparingly escaped from cultivation in NF, PQ, ON, and BC. First collected at Toronto, ON, by J. Groh in 1924. Only persists at a few locations in roadsides and waste places, in the Fraser Valley and on Vancouver Island of BC.

Lepidium species -weedy native pepper-grasses; lépidies
 Four, autogamous, annual or biennial pepper-grasses are native in some parts of Canada, but have colonized a wide range of artificially disturbed habitats both within and outside of their native ranges.

Lepidium bourgeauanum Thell. -Bourgeau’s pepper-grass.
 A biennial. In YT, NT-M, NF, NB, and PQ to BC. Native to Prairie Provinces but introduced elsewhere. 2n = 32, ON and BC (Mulligan 1961a).

Lepidium densiflorum Schrad. -common pepper-grass; lépidie densiflore.
 An annual. In YT, NT-M, and from NF to BC. Native to Prairie Provinces and interior of BC and introduced elsewhere. 2n = 32, ON, SK and BC (Mulligan 1961a,b and 1984).

Lepidium ramosissimum A.Nelson -western pepper-grass.
 A biennial. In NT-M, ON, MB, SK, AB, and BC. Native of Prairie Provinces and introduced elsewhere. 2n = 64, NT-M, SK and AB (Mulligan 1961a).

Lepidium virginicum L. -poor-man’s pepper-grass; lépidie de Virginie.
 An annual. In NF, PE, NS, PQ, ON and southwestern BC. Native to Fraser Valley and adjacent Vancouver Island in BC, but introduced in the east from further south in the United States. 2n = 32, ON and BC (Mulligan 1961a).

Lepidium aucheri Boiss.
 Introduced from Europe. Only specimen seen was collected on Bull grounds, Toronto, ON, by W. Scott on August 20, 1904.

Lepidium campestre (L.) R.Br. -field pepper-grass; lépidie des champs
 Autogamous annual or winter annual, introduced from Europe. First collected at Hamilton, ON, by J. M. Buchan in 1870 (Rousseau 1968). In all provinces of Canada; cultivated fields, roadsides, waste places, and railroad beds. Most common and abundant in the southern parts of PQ, ON, and BC; sporadic elsewhere. 2n = 16, ON, SK and BC (Mulligan 1957; Taylor and Mulligan 1968).

Lepidium heterophylum (DC.) Benth. -Smith’s pepper-grass; lépidie à feuilles dissemblables
 Perennial, introduced from Europe. Well established along roadsides and in waste places on Vancouver Island, B.C. First collected at Courtenay, BC, by W. E. Molyneux in 1955.

Lepidium latifolium L. -perennial pepper-grass; lépidie à feuilles larges
 Perennial, with subterranean rhizomes, introduced from Europe. Only known in Canada at Quebec, PQ, near Lethbridge, AB, and at Wycliffe, in the East Kootenay region of BC. It has persisted and spread locally at all three locations. It was first collected, in the railroad shop yard at Quebec, PQ, by Br. Marie- Anselm in 1931 and was discovered, in irrigated land, near Lethbridge, AB, by K. W. Hill in 1940. 2n = 24, AB (Mulligan 1957).

Lepidium oxycarpum Torr. & A. Gray. -forked pepper-grass
 Annual, introduced from the United States. Only Canadian specimen seen was collected at Cadboro Bay, Vancouver Island, BC, by J. Macoun in 1893.

Lepidium perfoliatum L. -clasping-leaved pepper-grass; lépidie perfoliée
 Autogamous annual, introduced from Europe. Often breaking off at base to act as a tumbleweed for seed dispersal. First collected at Osoyoos and Cranbrook, BC, by H. Groh in 1931. In southwest PQ, and in the southern parts of ON, MB, SK, AB, and BC. Most common in cultivated fields, overgrazed rangeland, roadsides, and waste places in the drier regions of the Prairie Provinces and inland valleys of BC.

Lepidium ruderale L. -roadside pepper-grass; passerage des decombres
 Autogamous annual or winter annual, introduced from Eurasia. First collected by J. Fowler at Bass River, NB, in 1868. Sporadic in roadsides, waste places and settlements from NF to SK.

Lepidium sativum L. -garden cress; lépidie cultivée
 Annual, introduced from Europe as a salad green. First collected at Ottawa, ON, by W. Scott in 1890. Sparingly escaped to roadsides, waste places and settlements in YT, NT-M, and from PE to BC.

Lobularia maritima (L.) Desv. -sweet alyssum; allysson maritime
 Perennial ornamental, native to the Mediterranean region, that normally acts as an annual under our conditions. First collected at Tring Junction, PQ, by H. Groh in 1927. Has been collected in NS, southern PQ and ON, and on Vancouver Island BC. It does not appear to persist except on Vancouver Island.

Lunaria annua L. -honesty; monnaie-du-pape
 Annual or biennial, native of Europe, grown for ornamental purposes. First collected at Revelstoke, BC, by H. Groh in 1939. Has been collected in old garden sites, roadsides, and waste places in NS, PQ, ON, MB, and BC. Does not persist.

Malcolmia maritima (L.) W.T.Aiton -Virginia stock; malcolmie maritime
 Annual ornamental, introduced from Europe. First collected as a garden escape, at Durham, ON, by W. Scott, in 1897. It has not been collected since that time.

Matthiola longipetala (Vent.) DC. ( = Matthiola bicornis (Sm.) DC.) -evening stock
 Annual or winter annual ornamental, native of Eurasia. First collected at Saskatoon, SK, by H. Groh in 1935. Collected, at a few sites, in settlements and roadsides, in ON, SK, and AB. Does not persist.

Myagrum perfoliatum L -mitre cress; myagrum perfolie
 Annual, native of Eurasia. Sometimes grown as an ornamental. Collected at Gallow’s Hill, PQ, by Brodie in 1895. The only other record is based on a specimen collected in the 1940s at Rigaud, PQ (Groh and Frankton 1946). There is no evidence that it can persist in nature.

Nasturtium crystallinum (Rollins) G.A.Mulligan -Asiatic cress
 Perennial with a very thick root. Probably introduced from Asia and utilized to produce a condiment. First collected by Thieret and Reich at mile 39, Yellowknife Highway, 26 miles northeast of Fort Providence, NT-M, in 1961. This is the only known location for this mustard in North America. Another specimen was collected, from the large patch growing at this site, by W. J. Cody in 1965. This is a location that was formerly farmed by a religious community. 2n = 32, NT-M ( Mulligan and Cody 1995).

Nasturtium microphyllum Boenn. ex Rchb. -northern water-cress; cresson de fontaine
 Perennial, aquatic to semi-aquatic, rooting at nodes. Introduced from Europe as a salad plant and has spread from deliberate plantings into cold streams. First collected, in Canada, at London, ON, by T. W. Burgess in 1879. Collected intermittently in cool water habitats in NF, PE, NB, PQ, ON, MB, and BC. Most common in southern ON. 2n = 64, PE and ON (Mulligan 1984).

Nasturtium officinale W.T.Aiton -southern water-cress; cresson de fontaine
 Perennial, aquatic to semi-aquatic, rooting at nodes. Introduced from Europe as a salad plant and has spread from deliberate plantings in cold streams. First collected, in Canada, at London, ON, by T. W. Burgess in 1878. Intermittently established in cool water in NF, NS, NB, PQ, ON, MB, AB, and BC. Most common in southwestern BC. Frequently confused with northern water-cress. Nasturtium officinale, a diploid (2 n = 32), is the most common water-cress in the United States, whereas Nasturtium microphyllum, a tetraploid (2 n = 64), is most common in Canada (Green 1962).

Neslia paniculata (L.) Desv. -ball mustard; neslie paniculée
 Self-compatible, autogamous, annual or winter annual, introduced from Europe. Pods, that do not open when ripe, are frequently an impurity in grain seed. First collected on a railroad embankment at Silver City, AB, by J. Macoun in 1885. In YT, NT-M, and all provinces from NF to BC. Common in grain and other cultivated fields in Western Canada, particularly in the Peace Rivers Districts of AB and BC. Sporadic elsewhere in roadsides, railway embankments, waste places, and near grain elevators. 2n = 14, ON and BC (Mulligan 1957; Taylor and Mulligan 1968).

Raphanus raphanistrum L. -wild radish; radis sauvage
 Annual or winter annual, introduced from Europe. Present in Nova Scotia as early as 1829 (Rousseau 1968). In all provinces from NF to BC. Very abundant in cultivated fields along the Atlantic seaboard and in the Fraser Valley and Vancouver Island of BC. Sporadically distributed elsewhere, mostly due to contaminants in grain shipments. 2n = 18, NB (Mulligan 1961b).

Raphanus sativus L. -radish; radis
 Annual, native of Mediterranean region, that is a sporadic escape from cultivation. Collected in NS, NB, PQ, ON, MB, SK, and BC, but does not persist, except in the Fraser Valley and Vancouver Island of BC. Sometimes hybridizes with wild radish in the Fraser Valley.

Rapistrum perenne (L.) All. -steppe cabbage; rapistre vivace
 Deep rooted perennial, introduced from Europe. First collected , at its only known location, at Grenfell, SK, in 1928 ( Groh 1944). It has persisted there and spread locally in roadsides, waste places, and cultivated fields.

Rapistrum rugosum (L.) All. -turnip weed; rapistre rugueux
 Annual, introduced from Europe. First collected at Montreal, PQ, by J. M. Wallace in 1893. Collected at a few widely separated sites, in waysides, and waste places in PQ and ON. Does not seem to persist.

Rorippa amphibia (L.) Besser -amphibious water cress; cresson amphibie
 Aquatic to semi-aquatic perennial, introduced from Europe. Rhizomes are believed to have been introduced at the port of Montreal, PQ, in ballast from early European ships. It occurs along the St. Lawrence River from Montreal to Quebec, PQ, and along the Richelieu River at St-Ours, PQ (see Rousseau 1968).

Rorippa austriaca (Crantz) Besser -Austrian yellow cress; cresson d’Autriche
 Rhizomatous perennial, introduced from Europe. First collected at Greenstreet, SK, by Patmore in 1932. In a few widely scattered localities in MB, SK, and AB. Is in pastures, cropland, and waste places, usually where moisture is plentiful.

Rorippa calycina (Engelm.) Rydb.  Rhizomatous perennial, probably introduced into Canada, from its native range further south in the United States, by migrating waterfowl. Only known, in Canada, from the mouth of the Anderson River, NT-M ( Mulligan and Porsild 1966). First collected by T. W. Barry in 1962, and in the same area by G. W. Scotter in 1965.

Rorippa sylvestris (L.) Besser -creeping yellow cress; rorippa sylvestre
 Rhizomatous perennial, introduced from Europe. Self-incompatible, rarely setting seed pods in nature. Spread mainly by root fragments. First collected at Ball’s Mills, Lincoln County, ON, by McCalla in 1897. In all provinces from NF to BC. Present in gardens, ditches, disturbed stream banks, moist meadows, plant nurseries, and waste places. 2n = 32, PQ and ON; 2n = 40, ON and BC; 2n = 48, NB, PQ, ON, AB and BC (Mulligan and Munro 1984).

Sinapis alba L. -white mustard; moutarde blanche
 Annual, native of Mediterranean region. Cultivated for the manufacture of mustard from seeds, and to a lesser extent for greens. Growing wild in Canada as early as 1860 (Groh and Frankton 1946). Sporadic in fields, disturbed prairie, roadsides, railway beds, and waste places, in PE and from PQ to BC. Often does not persist.

Sinapis arvensis L. -wild mustard; moutarde des champs
 Self-incompatible annual, introduced from the Mediterranean region. Common in fields of Albany, New York, as early as 1748, in NS in 1829 and by 1840 had reached the western and northern part of the state of New York and Lower Canada. In Fort Garry, MB, in 1860 and is now through all settled areas of Canada (Mulligan and Bailey 1975). Now in YT, NT-M, and all provinces. Jacobson et al. (1988) presented some evidence that charred seeds uncovered at excavations of abandoned native sites in the northeastern United States and dated at 8000 B.P. (before present), were wild mustard seeds. Rollins (1993) found their evidence unconvincing, and I agree with him. Very common in grain fields, other cultivated fields, and waysides in the Canadian prairie region, but less common elsewhere. It is a common contaminant in grain seed. Poisoning and death have occurred when large quantities of screenings were fed to animals (Mulligan and Munro 1990). See Warwick et al. (2000). 2n = 18, ON, MB, SK, AB and BC (Taylor and Mulligan 1968; Mulligan 1984; Warwick et al. 1994).

Sisymbrium altissimum L. -tumble mustard; sisymbre élévé
 Autogamous annual or winter annual, introduced from Eurasia. First collected at Silver City, AB, by J. Macoun in 1885. Often breaking off at the base, acting as a tumbleweed for seed dispersal. In YT, NT-M, and in all provinces from NF to BC. Most abundant in grain fields and grasslands of the prairies of Western Canada. Mostly in roadsides, railway beds, and waste places elsewhere in Canada. 2n = 14, ON, SK and BC (Mulligan 1961b, 1984; Taylor and Mulligan 1968).

Sisymbrium loesellii L. -tall hedge mustard; sisymbre de Loesel
 Autogamous annual or winter annual, introduced from Europe. First collected by N. Criddle in SK in 1929. Occurs from NB to BC. Most common in grain fields and other cultivated fields in the Prairie Provinces; sporadic in roadsides and waste places elsewhere. 2n = 14, AB (Mulligan 1957).

Sisymbrium officinale (L.) Scop. -hedge mustard; sisymbre officinal
 Annual, introduced from Europe. Seen at Prescott, ON, by B. Billings in 1862 (Rousseau 1968). Occurs in all provinces, except SK. Primarily a garden and waste place weed. It is often found near farm buildings. 2n = 14, BC (Taylor and Mulligan 1968).

Sisymbrium orientale L. -eastern tumble-mustard
 Annual herb, introduced from Eurasia. Rare in mesic to dry fields, roadsides, and waste places at Vancouver, BC (Douglas et al. 1998).

Teesdalia nudicaulis (L.) R.Br. -Shepherd’s cress; teesdalie à tige nue
 Annual or winter annual, introduced from Europe. Sporadically naturalized in disturbed habitats on southern Vancouver Island and in the Fraser Valley of BC. First collected in Locarno Park, Vancouver, BC, by J. Eastham in 1938, and it continues to persist at that site.

Thlaspi arvense L. -stinkweed; tabouret des champs
 Autogamous annual or winter annual, introduced from Europe. It was a common weed around Detroit as early as 1818 and, in Canada, at Fort Garry, MB, in 1865 (Best and McIntyre 1975). In YT, NT-M, and all provinces from NF to BC. In grain fields, hay fields, gardens, roadsides, and railway beds. When grazed, produces an off-flavor in dairy products (Frankton and Mulligan 1987). 2n = 14, ON, SK, and AB (Mulligan 1957, 1984; Pringle 1969).


Acknowledgments

The publications, Weeds of the Cruciferae (Brassicaceae) in North America (Rollins 1981) and Histoire, habitat et distribution de 220 plantes introduites au Québec (Rousseau 1968) have been especially useful to me. The common names are mostly from Common and scientific names of weeds in Canada/Noms populaires et scientifiques des plantes nuisible du Canada (Darbyshire et al. 2000). I am also indebted to the many people who documented the first sightings and later spread of our introduced mustards in their publications or by depositing specimens in various herbaria.

Documents Cited

Best, K. F. 1977. The biology of Canadian weeds. 22. Descurainia sophia (L.) Webb. Canadian Journal of Plant Science 57: 499-507.
Best, K. F., and G. I. McIntyre. 1975. The biology of Canadian weeds. 9. Thlaspi arvense L. Canadian Journal of Plant Science 55: 279-292.
Cavers, P. B., M. I. Heagy, and R. F. Kokron. 1979. The biology of Canadian weeds. 35. Alliaria petiolata (M.Bieb.) Cavara & Grande. Canadian Journal of Plant Science 59: 217-229.
Cayouette, J. 1984. Nouvelles stations du Barbarea stricta Andrz. au Québec. Le Naturaliste Canadien`111: 207-209.
Darbyshire, S. J., M. Favreau, and M. Murray. 2000. Common and scientific names of weeds in Canada/Noms populaires et scientifiques des plantes du Canada. Research Branch, Agriculture and Agri-Food Canada Publication 1397/B. 132 pages.
Dorofeev, V. I. 1998. The four new species of Brassicaceae in North America. Botanichiskii Zhurnal 83(9): 133-135.
Douglas, G. W., G. B. Straley, D. Meidinger, and J. Pojar. 1998. Illustrated Flora of British Columbia, Volume 2. Ministry of Environment, Lands and Parks, Victoria, British Columbia. 401 pages.
Frankton, C., and G. A. Mulligan. 1987. Weeds of Canada. NC Press Ltd., Toronto, Ontario. 217 pages.
Green, P. S. 1962. Watercress in the New World. Rhodora 64: 32-43.
Groh, H. 1944. Canadian weed survey, third annual report. Canada Department of Agriculture, Ottawa, Ontario. 70 pages.
Groh, H. 1945. Canadian weed survey, fourth annual report. Canada Department of Agriculture, Ottawa, Ontario. 56 pages.
Groh, H., and C. Frankton. 1946. Canadian weed survey, fifth annual report. Canada Department of Agriculture, Ottawa, Ontario. 86 pages.
Jacobson, H. A., J. B. Petersen, and D. E. Putnam. 1988. Evidence of pre-Columbian Brassica in northeastern U.S. Rhodora 90: 355-362.
Löve, Á., and D. Löve. 1982. IOPB chromosome number reports, LXXIV. Taxon 31: 125-126.
MacDonald, M. A., and P. B. Cavers. 1991. The biology of Canadian weeds. 97. Barbarea vulgaris R.Br. Canadian Journal of Plant Science 71: 49-166.
Mulligan, G. A. 1957. Chromosome numbers of Canadian weeds. I. Canadian Journal of Botany 35: 779-789.
Mulligan, G. A. 1959. Chromosome numbers of Canadian weeds. II. Canadian Journal of Botany 37: 81-92.
Mulligan, G. A. 1961a. The genus Lepidium in Canada. Madroño 16: 77-90.
Mulligan. G. A. 1961b. Chromosome numbers of Canadian weeds. III. Canadian Journal of Botany 39: 1059-1066.
Mulligan. G. A. 1964. Chromosome numbers of the family Cruciferae. I. Canadian Journal of Botany 42: 1509-1519.
Mulligan, G. A. 1965. Chromosome numbers of the family Cruciferae. II. Canadian Journal of Botany 43: 657-668.
Mulligan, G, A. 1966. Chromosome numbers of the family Cruciferae. III. Canadian Journal of Botany 44: 309-319.
Mulligan, G. A. 1975. Draba crassifolia, D. albertina, D. nemorosa, and D. stenoloba in Canada and Alaska. Canadian Journal of Botany 53: 745-751.
Mulligan, G. A. 1978. Barbarea stricta Andrz., a new introduction to Quebec. Le Naturaliste Canadien 105:298-299.
Mulligan, G. A. 1984. Chromosome numbers of some plants native and naturalized in Canada. Le Naturaliste Canadien 111: 447-449.
Mulligan, G. A. 1995. Synopsis of the genus Arabis (Brassicaceae) in Canada, Alaska, and Greenland. Rhodora 97: 108-188.
Mulligan, G. A. unpublished. Key to the Brassicaceae (Cruciferae) of Canada and Alaska.
Mulligan, G. A. 2002. Chromosome numbers determined from Canadian and Alaskan material of native and naturalized mustards, Brassicaceae (Cruciferae). Canadian Field-Naturalist 116: 611-622.
Mulligan, G. A., and L. G. Bailey. 1975. The biology of Canadian weeds. 8. Sinapis arvensis L. Canadian Journal of Plant Science 58: 171- 183.
Mulligan, G. A., and W J. Cody. 1995. New information on the problem of Asiatic cress, Rorippa crystallina Rollins (Brassicaceae). Canadian Field-Naturalist 109: 111-112.
Mulligan, G. A., and J. N. Findlay. 1974. The biology of Canadian weeds. 3. Cardaria draba, C. chalepensis, and C. pubescens. Canadian Journal of Plant Science 54: 149-160.
Mulligan, G. A., and C. Frankton. 1962. Taxonomy of the genus Cardaria with particular reference to the species introduced into North America. Canadian Journal of Botany 40: 1411-1425.
Mulligan, G. A., and C. Frankton. 1967. Present status of tall wormseed mustard, Erysimum hieraciifolium, in Canada. Canadian Journal of Botany 45: 755-756.
Mulligan, G. A., and D. B. Munro. 1984. Chromosome numbers and sexual compatibility in North American Rorippa sylvestris (Cruciferae). Canadian Journal of Botany 62: 575-580.
Mulligan, G. A., and D. B. Munro. 1990. Poisonous plants of Canada. Agriculture Canada Publication 1842/E. 96 pages.
Mulligan, G. A., and A. E. Porsild. 1966. Rorippa calycina in the Northwest Territories. Canadian Journal of Botany 44: 1105-1106.
Packer, J. G. 1964. Chromosome numbers and taxonomic notes on western Canadian arctic plants. Canadian Journal of Botany 42: 473-494.
Pringle, J. S. 1969. Documented plant chromosome numbers 1969:1. Sida 3: 350-351.
Rollins, R. C. 1981. Weeds of the Cruciferae (Brassicaceae) in North America. Journal Arnold Arboretum 62: 517-540.
Rollins, R. C. 1993. The Cruciferae of Continental North America. Stanford University Press, Stanford, California. 976 pages.
Rousseau, C. 1968. Histoire, habitat et distribution de 220 plantes introduites au Québec. Le Naturaliste Canadien 95: 49- 169.
Taylor, R. L., and G. A. Mulligan. 1968. Flora of the Queen Charlotte Islands, part 2, cytological aspects of the vascular plants. Queen’s Printer, Ottawa, Ontario. 148 pages.
Warwick, S. I., L. D. Black, and J. K. Anderson. 1994. IOPB chromosome data 7. IOPB Newsletter 22: 4- 5.
Warwick, S. I., H. J. Beckie, A. G. Thomas, and T. McDonald. 2000. The biology of Canadian weeds. 8. Sinapis arvensis L. (updated). Canadian Journal of Plant Science 80: 939-961.

 

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