Redroot pigweed
General poisoning notes:
Redroot pigweed (Amaranthus retroflexus) is a naturalized herb that is found across much of Canada. This plant can cause a variety of toxic problems, including perirenal edema in pigs. However, the nature of the toxic compound is not known. This plant can also accumulate oxalates to as much as 30% of dry weight. Redroot pigweed is capable of accumulating toxic concentrations of nitrates (Osweiler et al. 1985).
Description
Plantsdensely to moderately pubescent, especially distal parts of stem and branches. Stemserect, reddish near base, branched in distal part to simple 0.2-1.5(-2) m; underdeveloped or damaged plants rarely ascending to nearly prostrate. Leaves:petiole 1/2 to equaling blade; blade ovate to rhombic-ovate, 2-15 × 1-7 cm, base cuneate to rounded-cuneate, margins entire, plane or slightly undulate, apex acute, obtuse, or slightly emarginate, with terminal mucro. Inflorescencesterminal and axillary, erect or reflexed at tip, green or silvery green, often with reddish or yellowish tint, branched, leafless at least distally, usually short and thick. Bracts lanceolate to subulate, (2.5-)3.5-5(-6) mm, exceeding tepals, apex acuminate with excurrent midrib. Pistillate flowers:tepals 5, spatulate-obovate, lanceolate-spatulate, not clawed, subequal or unequal, (2-) 2.5-3.5(-4) mm, membranaceous, apex emarginate or obtuse, with mucro; style branches erect or slightly spreading,; stigmas 3. Staminate flowers few at tips of inflorescences; tepals 5; stamens (3-)4-5. Utriclesbroadly obovoid to broadly elliptic, 1.5-2.5 mm, shorter than or subequal to tepals, smooth or slightly rugose, especially near base and in distal part, dehiscence regularly circumscissile. Seeds black to dark reddish brown, lenticular to subglobose-lenticular, 1-1.3 mm, smooth, shiny.
Nomenclature:
Scientific Name: Amaranthus retroflexus L.
Vernacular name(s): redroot pigweed
Scientific family name: Amaranthaceae
Vernacular family name: amaranth
Amaranthus retroflexus L.
Geographic Information
Alberta, British Columbia, Manitoba, New Brunswick, Northwest Territories, Nova Scotia, Ontario, Prince Edward Island, Quebec, Saskatchewan.
Toxic parts:
Leaves, stems.
Notes on Toxic plant chemicals:
Nitrates have the following LD50 values (Crawford et al. 1966):
LD501.0 g/kg body weight in cattle
LD50 0.5 g/kg body weight in other ruminants.
LD50 0.5 g/kg body weight in other ruminants.
Acute poisoning occurs when forage nitrates exceed 1.0% nitrate (dry weight) or 1500 ppm in water (Osweiler et al. 1985). All Amaranthus spp. mentioned in this information system can accumulate toxic quantities of nitrates.
Toxic plant chemicals:
Nitrate.
Animals/Human Poisoning:
Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.
Cattle
General symptoms of poisoning:
abortion
bloat
blood brownish
breathing, rapid
death
dyspnea
kidney, edema of
mucous membrane, brown
nephrosis, severe
nervousness
recumbency
recumbency, ventral
regurgitation
weakness, posterior
Swine
General symptoms of poisoning:
ataxiadeath
gait, crouching
kidney, edema of
nephrosis, severe
recumbency, ventral
trembling
weakness.
