Euphorbiaceae - spurge family
Research Scientist and Research Institute Director (retired) and presently Honorary Research Associate, Agriculture and Agri-Food Canada,
Ottawa, Ontario K1A 0C6, Canada
Awarded the George Lawson Medal by the Canadian Botanical Association in 2006.
Awarded the Faculty of Macdonald, McGill University, Most Distinguished Alumni Award on October 18, 2014.
Read his biography "The Real Weed Man" available in print and ebook.
Acalypha virginica L. var. rhomboidea (Raf.) Cooperr., three-seeded mercury, ricinelle rhomboïde
An annual herb hat reproduces only by seed. It has erect, usually single, stems from 3 to 40 inches (7.5 to 100 cm.) tall. It occurs in the southern part of Nova Scotia, Quebec, and Ontario, and in the eastern and central United States. It is a native in moist soils of river flats and in the borders and openings of woods. It is naturalized as a weed in cultivated fields, ditches, roadsides and waste places. Young plants resemble both redroot pigweed and green pigweed, Amaranthus species (see photos under Amaranthaceae-amaranth family). Three-seeded mercury can be distinguished from both pigweeds by its glossy leaves, toothed leaf margins and the clusters of green flowers, with lobed bracts, in the axils of leaves.
Euphorbia cyparissias L., cypress spurge, euphorbe cyprès
Perennial, with underground rootstocks; most patches are sterile, and are very small, isolated, and spreading slowly; a few infestations, composed of fertile plants that set seed, become quite extensive; stems up to 1 foot (3 dm.) high; flowering inflorescences yellow; throughout most of our range, but most common in southeastern Quebec, southern Ontario, and southward into the eastern United States; roadsides, waste places, pastures, and open woods; often an escape from older cemeteries; introduced from Europe as an ornamental.
Euphorbia esula L., leafy spurge, euphorbe ésule
Perennial, spreading mainly by its persistent, vertical and horizontal underground roots, and much less by seed; stems erect, from 1 to 3 feet (3 to 9 dm.) high; flowering inflorescences from green to yellow; locally common throughout most of our area, particularly the mid-west; widespread, often very localized; a serious weed in native prairie and rangeland in the mid-west; grain fields, meadows, pastures, prairie, rangeland, roadsides, and waste places; introduced from Europe and Asia.
The milky juice of both of these spurges can cause a dermatitis in humans. Photosensitization, causing poisoning and death has occurred in animals after eating these spurges. However, most poisoning occurs when animals eat contaminated hay. Grazing animals usually avoid plants growing in the field.
Euphorbia vermiculata Raf., [= Chamaesyce vermiculata (Raf.) House], hairy-stemmed spurge, euphorbe vermiculée
Hairy-stemmed spurge is an annual herb with prostrate to semi-erect, sparsely pilose, stems. Its leaves are ovate to lanceolate, serrulate, and pilose on the lower surfaces. Capsules are glabrous, and are 1.5 to 2.0 mm long. Seeds have transverse wrinkles and are also 1.0 to 1.5 mm long. It is a native plant on sandy, gravelly and rocky shores of lakes and rivers, and is a weedy colonizer along roadsides and railway lines and in trampled areas around human habitation. It occurs in southeastern Canada, Vancouver Island in B.C., and in the northeastern United States, Arizona and New Mexico. It has a chromosome number of 2n= 16. Several other superficially similar annual prostrate spurges occur in our area.
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