Important Poisonous Vascular Plants of Australia

*Abrus precatorius

Gidee-gidee, rosary pea, precatory bean, jequirity bean, crab's eye, love bean

Perennial vine with pinnately compound leaves without tendrils; sprays of pink pea-type flowers followed by flat curled pods containing red and black seeds (used as jewelry, rosaries, rattles)

Native to India; widespread, sandy soils in tropical Australia (Queensland, Northern Territories, and Western Australia)

Ruminants and dogs less susceptible; horses, humans

Abrin (toxalbumin) causing severe gastroenteritis (sudden onset of vomiting, excess salivation, diarrhea leading to dehydration); gastric juice partially inactivates. Other compounds: indole identification helpful and diagnostic; toxicity similar to ricin

Immature or cracked seeds are the toxic part of the plant. Ingested whole, intact seeds are nontoxic. No effective treatment is known. Immunity possible. Treatment is symptomatic: fluid and electrolyte replacement; activated charcoal in known early exposure cases before clinical signs.

Acacia georginae

Georgina gidyea

(Largest genus of flowering plants in Australia)

Shrub or small tree with dark gray, fissured, flaky bark, "leaves" (phyllodes) gray-green and tapered at both ends with parallel veins and clusters of yellow, fluffy globular flowers in the "leaf" forks followed by flat, curved, and coiled seed pods

Arid zone; eastern central Australia

Cattle, sheep, horses, dogs (secondary poisoning)

Fluoroacetate—Seeds > pods > leaves; sudden death (acute heart failure). Dogs scavenging carcasses of poisoned production animals can be poisoned. Foliage has questionable hydrogen cyanide toxicity

Pods and young foliage are most toxic. No effective treatment is known. Restrict/limit exposure to pods bearing plants during dry periods.

*Adonis microcarpa

Pheasant's eye, Adonis

Native to Europe and temperate Asia. Annual herb with highly divided (ferny) leaves and glossy scarlet 5- to 8-petalled flowers

Weed of cultivation in temperate regions

Ruminants, horses, pigs

Cardiac glycosides– adonidin > leaves and flowers > fruits > stems and roots; cardiac arrhythmias, gastroenteritis (diarrhea with blood), dyspnea, sudden death

Seeds and whole plants have caused toxicity. Cardiac glycosides: oral activated charcoal, 5 g/kg with electrolyte replacement solution; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics. Symptomatic relief for diarrhea.

*Ageratina (Eupatorium) adenophora

Crofton weed, hemp agrimony

Shrub with numerous upright stems 1–2 m high; leaves opposite and trowel-shaped; white flowers in dense clusters at ends of stems

Native to Central America, naturalized weed of pastures in eastern coastal regions

Horses

Unidentified toxin causes coughing and decreased exercise tolerance progressing to dyspnea from chronic pulmonary inflammation and fibrosis. Heart failure in some cases.

Flowering plants are the most toxic. No effective treatment is known. Prevent access of horses to plant. Good pasture management practices help to decrease losses.

Agrostis avenacea

Blown grass, blow-away grass

Grass, tufted with spreading seedhead

Coastal and inland areas of subtropical and temperate regions

Ruminants, horses

Corynetoxins (tunicaminyluracils produced by Rathayibactertoxicus bacteria in seedhead nematode galls) cause "floodplain staggers," with convulsions and death in most cases.

Corynetoxins: a cyclodextrin toxin binding agent is under development as an antidote.

Alstonia constricta

Bitter bark, quinine tree, Peruvian bark

Tree up to 12 m, frequently suckering to form thickets; corky bark; leaves opposite; milky sap; cream, star-shaped flowers in clusters at ends of branches; long, narrow pods with seeds bearing silky hair tufts

Widespread in coastal and inland southern Queensland and northeastern New South Wales

Ruminants; dogs may be poisoned by meat from poisoned ruminants.

Not clearly identified. Indole alkaloids (alstonine, echitamine alstonidine, and reserpine isolated from leaves, fruits, bark, and roots are suspects); tetanic spasms of skeletal muscles

Leaves and fruit are toxic. Maintain high levels of nutrition Deny further access to plants. Serious cases may benefit from heavy sedation.

*Ammi majus

Bishop's weed, greater ammi, meadow sweet

Annual or biennial herb with upright stems, pinnately compound ferny leaves, and small, white flowers in flat-topped clusters

Native to Mediterranean region, weed of cultivation along roadsides in temperate regions

Ruminants, horses, and poultry

Furanocoumarins in seeds and green plants; primary photosensitization, including corneal edema

Supportive treatment for photosensitization (shade, anti-inflammatory, rehydration). No specific treatment available. Deny further access to plants.

*Anthoxanthum odoratum

Sweet vernal grass

Grass, tufted upright with tapered cylindrical seedhead

Coastal and subcoastal in temperate regions. A weed of pasture.

Cattle

Dihydroxycoumarin produced in moldy hay or silage causes coagulation defects and extensive hemorrhage in affected animals.

Toxin is transported across the placenta and through milk. Treat with vitamin K₁ injections.

Arctotheca calendula

Cape weed

Annual herb with leaves in rosette; hairy on lower surfaces; bright yellow, daisy-type flowers with dark centers

Weed of cultivation in southern regions

Ruminants

Nitrates—methemoglobinemia

Toxicity is most likely from rapid large plant intakes. Nitrates: IV methylene blue.

*Argemone spp

A ochroleuca

Prickly poppies,

Mexican poppies

Upright, thistle-like herbs with variegated, gray-green, deeply divided, spiny leaves; large, pale or deep yellow 4- to 6-petalled flowers followed by seed capsules with small, dark seeds; cut stems exude bright yellow sap

Widespread weeds of cultivation

Poultry, ruminants

Isoquinoline alkaloids cause heart failure with cardiomyopathy, pulmonary and subcutaneous edema. Presence of nitrate in potentially toxic levels, but no reported toxicity.

Seeds are the most toxic part; however, dry plants in hay may be toxic. No effective treatment is known. Seeds crushed and exposed to sunlight are detoxified.

*Asclepias curassavica

Red-head cotton-bush, red cotton

Shrub with upright stems, milky sap, simple-tapered leaves, red and yellow flowers, and tapered seed pods with tufted seeds

Weed of pasture and cultivation in northern regions

Cattle

Cardiac glycosides (cardenolides)—cardiac arrhythmias, diarrhea with blood, dyspnea, sudden death

Cardiac glycosides: oral activated charcoal; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics.

Atalaya hemiglauca

Whitewood

Small tree < 6 m high with pale gray, flaky bark with compound leaves consisting of 1–3 pairs of narrow leaflets and cream flowers in bunches at the end of branches, followed by winged fruit

Widespread in the inland regions of mainland states. Soil type loose sand to clay.

Horses

Unidentified toxin. A syndrome of cardiac failure is reported with severe edema of the head, muscle weakness, and myoglobinuria. Hemolytic saponins isolated

Young shoots and fruit are regarded as the toxic parts. Poisoning occurs when the plant is a large portion of the diet. No effective treatment is known. Maintain high nutrition levels of animals.

*Avena sativa

Oats, cultivated oats

Annual or perennial grass, upright

Crop in temperate and subtropical areas

Ruminants, horses

Nitrates—methemoglobinemia. Abrupt weakness, dark-colored blood and mucous membranes are primary clinical signs. Unknown toxin in "rusty" or "red-tipped" fodder oats causes transient hyperesthesia and diarrhea in cattle. Unknown photosensitizing toxin (grazing green forage for several weeks).

Nitrate toxicity is most likely from rapid large plant intakes. Nitrates: IV methylene blue. Hypomagnesemia: ingestion of lush, young growth; pasture management, top dressing with magnesium; supportive treatment for photosensitization (shade, anti-inflammatory, rehydration).

Boweni spp

B serrulata/B spectabilis

Byfield "fern," Zamia "fern."

(There are two species, both endemic to Queensland, Australia.)

Fern-like plants with groups of leathery, highly divided leaves arising from underground trunks. Sexes are separate, bearing cones at the apex of the plant.

Open forests and rainforests of northeastern Australia; cultivated in gardens

Cattle, sheep, and dogs

Toxicity–hepatotoxic and neurologic effects similar to Cycas. Unidentified neurotoxin (glycosides and amino acid)—permanent spinal cord degeneration with caudal ataxia in cattle ("zamia staggers"). Methylazoxymethanol—liver necrosis

Seeds, stem, and young leaves are the most toxic parts. No effective treatment is known for either syndrome. Supportive care for hepatic condition.

*Brachiaria spp

(B decumbens, B brizantha)

Signal grass

B mutica

Para grass, giant panicum

Grasses, tufted or sprawling

Cultivated tropical pasture grasses

Ruminants, horses

Steroidal saponins—hepatogenous photosensitization in ruminants; calcium oxalate crystals deny calcium to horses producing nutritional secondary hyperparathyroidism (lameness, weight loss, jaw swelling)

Supportive treatment for photosensitization (shade, anti-inflammatory, rehydration). No specific treatment available. Calcium oxalate (horses): remove from the pasture and remineralize bones by feeding a mineral supplement with a Ca:P ratio of 2:1

Brachyachne spp

Native couches

B convergena

Native couch, Kimberley

B ciliaris

Hair native couch

B tenella

Slender native couch

Grasses, sprawling or erect with digitate seed heads

Native pasture grasses of northern inland regions

Ruminants, horses (when other sources of forage are scarce)

Cyanogenic glycosides (highest in young growing plants, lowest in flowering stage)—sudden death

Toxicity is most likely from rapid, large, plant intakes. Cyanogenic glycosides: IV sodium thiosulfate; repeat treatment may be needed for relapse.

*Brunfelsia spp

Francisia, yesterday-today-and-tomorrow

Ornamental shrub with dense foliage and conspicuous broad flowers opening purple and fading to white, followed by brown to black berries

Cultivated garden plant (native to the West Indies)

All, but dogs are most frequently reported

Unidentified toxin (brunfelsamidine a possible suspect) causing vomiting, diarrhea, muscle tremors, and clonic/tonic convulsions (similar to those that occur in strychnine toxicity)

Fruits are toxic. Dogs attracted to ripe fruits will eat large amounts. Symptomatic: treat with an emetic followed by oral activated charcoal with saline cathartic, with an anticonvulsant or anesthetic to treat seizures.

*Bryophyllum (Kalanchoe) spp

B tubiflorum, B daigremontianum

Mother-of-millions

Erect, succulent herbs with fleshy leaves (pencil-shaped to broad and lobed depending on species) and showy clusters of hanging tubular flowers with red petals at the top of stems

Native or naturalized weedy garden escape of northeastern regions; prefers shaded habitat on leaf litter

Cattle

Cardiac glycosides (bufadienolides)—cardiac arrhythmias, diarrhea with blood, dyspnea, sudden death

Flowering plants are most toxic and poisoning cases are confined to winter when the plants flower. Cardiac glycosides: oral activated charcoal; treat arrhythmias with atropine and propranolol.

*Cascabela thevetia (Thevetia peruviana)

Yellow oleander

Shrub or small tree; milky sap; tapered, simple, leathery, alternate leaves; bright yellow, trumpet-shaped flowers; fleshy fruit turning black when ripe

Cultivated garden plant; naturalized in some areas

Cattle, horses

Cardiac glycosides (cardenolides) in all parts (kernels of fruits most toxic)—cardiac arrhythmias, gastrointestinal effects, diarrhea with blood, dyspnea, sudden death (similar to Nerium toxicity)

Cardiac glycosides: oral activated charcoal; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics.

Castanospermum australe

Black bean

Tree, usually up to 20 m tall, with compound leaves and clusters of red and yellow, pea-type flowers on branches, followed by large seed pods containing large, fleshy, brown seeds

Riverine forest of eastern Australia; sparingly cultivated

Cattle, horses

Unidentified toxin causing GI tract irritation; castanospermine (polyhydroxy alkaloid), a glucosidase inhibitor, is not responsible for poisoning.

Toxicity only occurs with persistent consumption of large numbers of ripe seeds, most likely under drought conditions. No effective treatment is known.

*Cenchrus ciliaris

Buffel grass

Grass, tufted forming tussocks, with crowded seedheads containing numerous bristly spikelets

Naturalized (mainland states) tropical pasture grass; weedy in arid zone

Ruminants, horses

Soluble oxalates—hypocalcemia, nephrosis in ruminants but not horses. Calcium oxalate crystals deny calcium to horses, producing nutritional secondary hyperparathyroidism (lameness, weight loss, head swelling).

Ruminants are susceptible only if very hungry and have access to very lush grass. Soluble oxalates: calcium borogluconate injection (prognosis guarded). Calcium oxalate (horses): remove from the pasture and remineralize bones by feeding a mineral supplement with a Ca:P ratio of 2:1

*Cestrum parqui

Green cestrum

Multistemmed, erect shrub with leaves tapered at both ends and clusters of tubular, yellow flowers at the end of stems, followed by black berries

Cultivated garden plant; naturalized in eastern Australia

Ruminants, horses, pigs, poultry

Diterpenoid (kaurene) glycosides parquin and carboxyparquin cause acute coagulation necrosis of periacinar hepatocytes, with rapid death after hepatoencephalopathy in some cases

No effective treatment is known.

Cheilanthes sieberi

Mulga fern, rock fern

Small, upright fern with dark stems and small leaves. A xerophytic (drought-resistant) fern, often the first green plant available in pasture after drought-breaking rains

Widespread in woodlands of inland and coastal parts of subtropical and temperate regions

Cattle, sheep

Ptaquiloside (see Pteridium esculentum below). Thiaminase (see Marsilea drummondii below).

Ptaquiloside­: no effective treatment is known. Thiaminase: IV thiamine (vitamin B₁) is effective.

*Citrullus spp

Colocynth, pie melons

*Cucumis spp

Paddy melons

Vines with yellow flowers and melon-like fruit

Widespread weeds of inland arid regions

Cattle

Uncertain at best. Cucurbitacins—irritation of the upper GI tract and increased permeability of blood vessels producing sudden death with diarrhea

Ripe fruits are the most toxic part of the plants. Poisoning occurs when cattle have access to large quantities. No effective treatment is known. Rumenotomy to remove fruits could be considered.

*Corchorus olitorius

Jute

Erect, annual herb with alternate leaves, each bearing two elongated basal stipules, yellow 5-petalled flowers, dark cylindrical seed pods

Weed of cultivation and pasture in northern Australia

Cattle, horses, pigs

Cardiac glycosides—cardiac arrhythmias, diarrhea with blood, dyspnea, sudden death

Seeds are toxic as contaminants of fed grains. Cardiac glycosides: oral activated charcoal; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics.

Crotalaria spp

Rattlepods

Herbs to shrubs with either simple or trifoliate leaves and bright yellow pea-type flowers on spikes, followed by inflated seedpods

Native and naturalized in subtropical and tropical areas; some species are weeds of cultivation and pasture.

Ruminants, horses, pigs

Pyrrolizidine alkaloids—chronic hepatopathy causing weight loss, irritability and compulsive walking (horses) or weight loss and persistent diarrhea with tenesmus (cattle). Rarely, horses may develop pulmonary adenomatosis and severe dyspnea after eating certain species that contain monocrotaline and similar pneumotoxic alkaloids. Pigs develop nephrosis rather than hepatopathy. Unknown toxin(s) in Crotolaria aridicola and Crotolaria medicaginea causes severe esophageal ulceration in horses.

15 species have been associated with toxicity of animals in Australia. Pigs have been poisoned by Crotalaria retusa seeds contaminating feed grain. No effective treatment for hepatotoxicity. If a stomach tube can be passed in cases of esophageal ulceration, affected horses should recover with symptomatic treatment.

*Cryptostegia grandiflora

Rubber vine

Vine, multistemmed with oval leaves, pink trumpet-shaped flowers, and rigid paired pods

Weed of pasture in northeastern regions

Cattle, horses

Cardiac glycosides (cardenolides)—cardiac arrhythmias, diarrhea with blood, dyspnea, sudden death

Cardiac glycosides: oral activated charcoal; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics.

*Cupressus macrocarpa

Monterey cypress

Tree, up to 20 m tall, densely branched with dark green foliage

Cultivated in temperate areas, often as windbreak trees

Cattle

Isocupressic acid and/or vasoactive lipids—abortion/premature birth

No effective treatment is known. Separating production animals from windbreaks by fencing provides effective prevention.

Cycas spp

Zamias, zamia "palm" (27 species endemic to Australia)

*Cycas revoluta

Sago "palm"

Tree-like plants with trunks surmounted by rosettes of leathery leaves, with numerous leaflets. Sexes are separate. Male cones produced at the apex; female cones divided into separate, leaf-like structures bearing naked seeds on their margins

Open forest and woodlands of northern Australia, mostly coastal to subcoastal; sago "palm" from the Japanese islands is cultivated in gardens

Cattle, dogs

Unidentified neurotoxin causing permanent spinal cord degeneration with caudal ataxia in cattle ("zamia staggers"). Methylazoxymethanol—liver necrosis. Dogs eating seeds of cultivated specimens of Cycas revoluta have been affected.

Seeds and young leaves are the most toxic parts. No effective treatment is known.

Dactyloctenium radulans

Button grass

Grass, spreading from central tuft with spikelets in star-like clusters

Widespread native pasture grass in all mainland states

Cattle, sheep

Nitrates—methemoglobinemia

Dangerous only when growing in heavily fertilized soils such as in stockyards and available to hungry animals. Nitrates: IV methylene blue

Dendrocnide spp (D moroides, D cordata, D excels, D photinophylla)

Stinging trees

Shrubs to trees with broad, heart-shaped leaves bearing numerous stinging hairs with small flowers in bunches, followed by fleshy fruits

Rainforests of northeastern regions

Horses, humans

Moroidin (a bicyclic octapeptide) is thought at least partly responsible for intense and persistent local pain caused by contact with stinging hairs on the leaf surfaces. Horses can be driven to frenzy by contact. Pain in humans can persist for several weeks after contact.

No effective treatment is known. Prompt euthanasia should be considered in affected horses.

Duboisia hopwoodii

Pituri

Shrub, up to 3 m tall, with long, narrow leaves and groups of white, bell-shaped, purple-striped flowers at ends of branches, followed by black berries

Arid regions from central Australia to the western coast

Ruminants, horses, and camels

Nicotine causing incoordination, muscle tremors, dilated pupils (impaired vision), recumbency, clonic seizures, diarrhea.

No effective treatment is known. Affected animals left undisturbed often recover.

Duboisia myoporoides, D leichhardtii

Corkwoods

Small trees with corky bark, simple leaves, and white tubular flowers in bunches at branch ends, followed by black berries

Coastal and inland eastern Australia

Ruminants, horses, and humans

Tropane alkaloids causing dilated pupils (impaired vision), tachycardia, convulsions; paralytic ileus or impaction colic, gastric rupture, and hemorrhagic gastroenteritis are reported in horses.

Physostigmine

*Echium plantagineum (E lycopis)

Patterson's curse, salvation Jane

Annual herb with rosette of broad, hairy leaves and erect flowering stalk, with blue flowers crowded along one side of the curled spikes at end of branches

Weed of cultivation and pasture in southern regions

Cattle, horses, sheep

Pyrrolizidine alkaloids—chronic hepatopathy causing mostly weight loss, irritability, and compulsive walking (horses) or weight loss and persistent diarrhea with tenesmus (cattle)

No effective treatment is known.

Eremophila maculata

Spotted emu bush, native fuchsia, fuchsia bush

Densely branched shrub, 1–2 m tall, with dark green tapered leaves and red tubular flowers with spotted throats carried on S-shaped stalks, followed by round, hard fruits with papery skin

Inland regions of mainland states

Ruminants

Cyanogenic glycosides (prunasin)—sudden death

Young leaves are the most toxic part of the plant. Toxicity is most likely from rapid, large plant intake. Cyanogenic glycosides: IV sodium thiosulfate, repeat for relapses.

Eremophila (Myoporum) deserti

Ellangowan poison bush, turkey bush

Myoporum accuminatum

Boobialla, strychnine bush

Shrubs or small trees with leaves tapered at both ends and small, white, bell-shaped flowers, hairy inside, followed by purple, black, or yellow berries

Inland regions of mainland states

Ruminants

Furanosesquiterpenes cause acute coagulation necrosis of hepatocytes, with rapid death after hepatoencephalopathy in some cases. Similar toxic manifestations—common to both species, Toxic responses (photosensitization and jaundice) may be delayed for days after ingestion.

Some individual plants are nontoxic. No effective treatment is known. Prevention: plant identification and limited access of production animals to plants.

Erythrophleum chlorostachys

Cooktown ironwood, camel poison, black bean

Tree, up to 15 m, with compound leaves consisting of leaflets with unequal amounts of blade on either side of the midvein, bipinnate; flower spikes with yellow-green flowers, followed by dry, brown, flat seed pods

Open woodland in northern and Western Australia; sandy soils

Ruminants, horses, donkeys, camels

Diterpenoid alkaloids and cinnamic acid derivatives; produce sudden death with effects similar to those of cardiac glycosides.

All parts can be fatally toxic in small doses. Suckers accessible to grazing animals. Dry leaves remain toxic. No effective treatment is known; however, the regimen for cardiac glycosides could be applied, eg, oral activated charcoal; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics.

Eucalyptus cladocalyx

Sugar gum

Tree, up to 30 m, with white or yellow-brown, smooth bark, adult leaves strongly different shade of green on upper and lower surfaces (discolorous), rubbed buds, white flowers, and barrel-shaped fruit

Southeastern states; commonly grown as windbreaks

Ruminants

Cyanogenic glycosides (prunasin—loses potency in storage)—sudden death

Young leaves are the most toxic part of the plant. Toxicity is most likely from rapid, large plant intakes. Cyanogenic glycosides: IV sodium thiosulfate. Repeat for relapses.

Euphorbia spp

Spurges

Prostrate to erect succulent herbs with milky sap and unusual inflorescences (cyathiums)

Toxic species occur in inland areas

Ruminants

Irritant toxins of uncertain identity—alimentary tract irritation, diarrhea. Cyanogenic glycosides suspected in some species—sudden death

Toxicoses (other than irritant induced): most likely from rapid large plant intakes are not fully investigated; thus, no known effective treatment. Cyanogenic glycosides: IV sodium thiosulfate. Repeat for relapses.

Gastrolobium spp

Poison bushes

Shrubs, most with opposite leaves or leaves in rosettes around stems, terminal racemes of pea-type flowers with red and yellow or all-red petals, followed by small, hairy seed pods

Most species are concentrated in shrublands or southwestern Australia, with one species in central and northeastern Australia

Ruminants, horses, dogs (secondary poisoning)

Fluoroacetate (leaves, flowers, and seeds)—sudden death. Dogs scavenging carcasses of poisoned production animals can be poisoned.

34 species are toxic and 8 more are suspected. No effective treatment is known.

*Glyceria maxima

Reed sweet grass

Grass, erect, 90–250 cm high, with an open, branched seedhead

Temperate regions in semiaquatic habitats such as on the margins of water storage dams

Ruminants

Cyanogenic glycosides— sudden death.

Cyanide toxicity is most likely from rapid, large plant intakes, eg, by hungry animals. Cyanogenic glycosides: IV sodium thiosulfate. Repeat treatment may be needed for relapses.

*Gomphocarpus spp

Balloon cotton

Shrub with upright stems, milky sap, simple, tapered leaves, white flowers, and inflated seed pods with tufted seeds

Weed of pasture and cultivation in northern regions

Cattle

Cardiac glycosides—cardiac arrhythmias, diarrhea with blood, dyspnea, sudden death.

Cardiac glycosides: oral activated charcoal; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics

*Heliotropium europaeum

Common heliotrope

H amplexicaule

Blue heliotrope

Annual/perennial herbs with branched stems bearing green to gray-green, simple leaves and flowering stems with white (Heliotropium europaeum) or blue (H amplexicaule) flowers crowded on one side of the curled spikes at the ends of branches

Weeds of cultivation and pasture in southern regions

Cattle, horses, pigs, sheep, poultry

Pyrrolizidine alkaloids—chronic hepatopathy causing mostly weight loss, irritability, and compulsive walking (horses) or weight loss and persistent diarrhea with tenesmus (cattle).

Seeds of Heliotropium heuropaeum contaminating feed wheat have poisoned pigs and poultry. No effective treatment is known.

Heterodendron oleifolium

Boonaree, rosewood, bullock bush

Tree, up to 7 m tall, with dark gray, furrowed, and flaky bark, pale green inconspicuous flowers, followed by rounded fruits

Inland regions of mainland states

Ruminants

Cyanogenic glycosides—sudden death.

The plant is regarded as safe fodder unless fed in large amounts during droughts. Toxicity is most likely from rapid, large plant intake. Cyanogenic glycosides: IV sodium thiosulfate, 660 mg/kg, plus an oral dose (30 g cattle, 5 g sheep). Repeat for relapses.

*Homeria flaccida

One-leaf cape tulip

H miniata

Two-leaf cape tulip

Herbs growing from underground corms, forming a leaf or leaves and branched flowering stems with 6-petalled, salmon-pink flowers

Naturalized in temperate regions of southern Australia

Ruminants

Cardiac glycosides (bufadienolides)—cardiac arrhythmias, diarrhea with blood, dyspnea, sudden death.

Toxicity has occurred from access in pasture or in hay. Cardiac glycosides: oral activated charcoal; treat arrhythmias with atropine and propranolol; horses should receive analgesics/antispasmodics.

Hoya australis

Wax flower

Vine with fleshy round leaves, milky sap, and bunches of waxy, white flowers

Rocky areas and vine forests ("dry" rainforests) in coastal and subcoastal Queensland and New South Wales

Cattle, sheep

Unidentified neurotoxin (probably a resinoid)—muscle tremors, ataxia, collapse, clonic/tetanic convulsions.

No effective treatment is known.

Indigofera linnaei

Birdsville indigo, 9-leaved indigo

Prostrate herb with compound leaves and tight clusters of scarlet, pea-type flowers followed by hairy seed pods

Widespread in tropical Queensland, Northern Territory, and Western Australia

Horses, dogs (secondary poisoning)

Unknown; Probable nitrotoxin causing lethargy, spinal cord damage, and caudal ataxia in horses. Amino acids indospicine and/or canavanine—arginine antagonists. Indospicine residues in horse meat has caused severe hepatopathy in dogs.

Horses are poisoned when the plant forms a dominant part of pastures in inland areas and is grazed for several weeks. No specific effective treatment is known; however, horses drenched with gelatine in warm water, 450 g/kg for 3 days, improved. Fencing off the plant, heavy grazing by small ruminants, or feeding horses good quality lucerne hay, peanut meal, or cotton seed meal can prevent cases. Arginine-rich feed supplementation might be protective.

Ipomoea batatus

Sweet potato

Vine with arrowhead-shaped leaves and trumpet-shaped, pink flowers

Cultivated crop

Ruminants

Pneumotoxic furanoterpenes (3-substituted furans)—severe dyspnea from interstitial pneumonia and edema.

Only moldy tubers are toxic. Removal of moldy tubers from the feed results in recovery in most affected animals.

Ipomoea muelleri

Poison morning glory

Vine with arrowhead-shaped leaves and trumpet-shaped, pink flowers

Central and northwestern regions

Ruminants, horses

Unknown toxin, probably calystegines—incoordination, nervous derangement.

No effective treatment is known.

Ipomea calobra

Weir vine, calobra vine

Vine with arrowhead-shaped leaves and trumpet-shaped, pink flowers

Localized to clay soils of Maranoa district, Queensland

Ruminants, horses

Calystegines, swainsonine—acquired lysosomal storage of mannose leading to incoordination, nervous derangement, weight loss, polyuria.

Animals are reputed to develop a craving for the plants. Toxicity requires access for 4 weeks or more. No effective treatment is known. Less severely affected animals recover if access is prevented.

Isotropis spp

Lamb poisons, granny bonnets, poison sage, bloom poison

Closely related to Gastrolobium and Oxylobium genera (fluoroacetate-containing plants)

Shrubs or herbs with pea-type flowers with conspicuous radiating branched lines on the back of the large, erect, standard petal; flowers are purple, yellow, or orange

Most species confined to southwestern Australia, with one in central Australia

Ruminants

Unknown. Iforrestine (heterocyclic alkaloid)—nephrosis.

No effective treatment is known.

*Jatropha spp

Shrubs and small trees with inconspicuous or bright red flowers and seed pods

Cultivated garden plants, some species are naturalized and weedy in northern Australia

Ruminants, horses

Irritant toxins of uncertain identity—alimentary tract irritation, diarrhea.

No effective treatment is known.

*Lamium amplexicaule

Dead nettle

Erect herb up to 30 cm tall, with opposite, rounded, lobed leaves on square stems and tubular, pinkish flowers subtended by cup-shaped leaves around the stem

Widespread weed of cultivation

Ruminants, horses

Unidentified toxin causing incoordination.

Removal from access to plants results in recovery in most cases.

Leiocarpa (Ixiolaena) brevicompta

Flat billy buttons, button weed, plains plover daisy

Low-growing shrub up to ~30 cm tall, with numerous flat-topped, dense, yellow flower heads

Heavy clay soils of the floodplains of the Darling river system in Queensland and New South Wales

Sheep

Unknown. Crepenynic acid and other fatty acids cause striated muscle degeneration, severely decreased exercise tolerance, muscle weakness, and recumbency.

Toxicity is from eating mature seedheads in quantity. No effective treatment is known. Affected sheep recover in some cases.

Lepidozamia spp

Zamias (There are two species, both endemic to Australia, one commonly cultivated in gardens)

Tree-like plants with trunks surmounted by rosettes of leaves with numerous leaflets. Sexes are separate, bearing cones at the apex of the plant.

Open forests and rainforests of northeastern Australia; cultivated in gardens

Cattle

Unidentified neurotoxin—permanent spinal cord degeneration with caudal ataxia in cattle (zamia staggers). Methylazoxymethanol—liver necrosis

Seeds and young leaves are the most toxic parts. No effective treatment is known.

*Leucaena leucocephala

Lead tree

Shrub to small tree with bipinnate (fern-like) leaves, pale yellow globular flowers, followed by long, flat, brown seed pods

Native to Central America. Cultivated and naturalized browse shrub in tropical regions; weedy in some situations

Ruminants, horses

Mimosine and derivatives in young leaves and seeds—hair loss (ruminants, horses); goiter, cataracts, and buccal erosions (ruminants)

No effective treatment is known. Ruminal bacterium (Synergistes jonesii) detoxifies mimosine and derivatives. Detoxification capacity is retained as long as mimosine is in the diet, the bacteria surviving up to 9 months after access stops. Ferrous sulfate supplementation may help monogastric animals.

*Lolium perenne

Perennial ryegrass

Grass, tufted with flattened, flowering spike with spikelets arranged in a zig-zag pattern

Cultivated temperate pasture grass

Ruminants

Lolitrems (tremorgenic mycotoxins from the endophytic fungus Neotyphodium lolii cause perennial ryegrass staggers (muscle tremor, head bobbing/weaving, stiff high-stepping gait, collapse, recovery if undisturbed). Nitrates—methemoglobinemia.

Lolitrems are concentrated in leaf sheaths, making toxicity most likely on well-cropped pasture. No effective treatment available. Nitrates: IV methylene blue.

*Lolium rigidum

Annual ryegrass

Grass, tufted with flattened, flowering spike, with spikelets arranged in a zigzag pattern

Cultivated temperate pasture grass; naturalized weed in southern Australia

Ruminants, horses

Corynetoxins (tunicaminyluracils produced by Rathayibacter toxicus bacteria in seedhead nematode galls) cause annual ryegrass toxicity with convulsions and death in most cases. Ergot alkaloids when seeds infested by Claviceps purpurea (rye ergot) cause agalactia and hyperthermia in pigs and cattle fed grain contaminated with ergot bodies.

Corynetoxins: a cyclodextrin toxin binding agent is under development as an antidote. Ergot alkaloids: dopamine antagonists may be helpful, domperidone, metaclopromide, reserpine.

Lotus spp

Birdsfoot trefoils

Herbs with compound leaves consisting of five leaflets, three at the tip and two at the base, and pea-type flowers with red, yellow, pale pink, or white petals

Subtropical and temperate regions in all states

Ruminants

Cyanogenic glycoside—sudden death

Toxicity is most likely from rapid, large plant intake. Cyanogenic glycosides: IV sodium thiosulfate. Repeat for relapses.

*Lupinus spp

Lupines

Robust herbs with compound leaves with radiating leaflets and flower spikes crowded with pea-type yellow, white, or blue flowers, followed by hairy seed pods

Cultivated grain crops in southern regions

Ruminants

Phomopsins produced by the fungus Diaporthe toxica growing in dead plants—chronic hepatopathy causing weight loss and jaundice with photosensitization in some cases and myopathy in others.

Most toxicity occurs if dry lupine stubble is grazed after grain harvest. No effective treatment is known. Selenium/vitamin E may help myopathy cases. Immunization against phomopsins is being developed as a control measure.

*Lythrum hyssopifolia

Lesser loosestrife

Herb with ribbed stems and simple, small leaves with single pink to purple, tubular flowers in leaf axils

Weed of pasture in temperate areas

Sheep

Unidentified toxin causing renal tubular and hepatocyte necrosis

Poisoning commonly occurs when sheep graze on crop stubbles in which the plant is dominant. No effective treatment is known.

Macadamia spp

Trees with oblong leaves carrying a few marginal spines, and hanging sprays of cream flowers, followed by a globular fruit containing a hard, brown nut

Cultivated tree; nuts harvested as food

Dogs

Unidentified toxin; produces muscular weakness and joint pain

Both fresh and roasted kernels are potentially toxic. Clinical signs are transient with recovery occurring within 24 hours, with or without symptomatic treatment.

Macrozamia spp

Zamias, burrawang, zamia "palm"

(There are ~40 species, all endemic to Australia)

Tree-like plants with trunks surmounted by rosettes of leathery leaves with numerous leaflets. Small species have no trunks. Sexes are separate, bearing cones at the apex of the plant.

Open forests and woodlands of southern and central Australia; some cultivated in gardens

Cattle, sheep (rare), dogs

Unidentified neurotoxin—permanent spinal cord degeneration with caudal ataxia in cattle (zamia staggers). Methylazoxymethanol—animals eating seeds of cultivated specimens of Macrozamia riedlei have been affected.

Seeds and young leaves are the most toxic parts. No effective treatment is known.

*Malva parviflora

Marsh or small flowered mallow

Herb with rounded, seven-lobed, pleated leaves on stalks and with white to very pale pink or lavender flowers in clusters in the leaf forks, followed by button-shaped fruit

Widespread weed of cultivation

Ruminants, poultry

Unidentified toxin causing skeletal muscle necrosis. Nitrates—methemoglobinemia. Malvic acid causes pink discoloration of egg whites and pasty yolks from hens eating seeds (or leaves).

Toxicity is most likely from rapid, large plant intake. Nitrates: IV methylene blue.

Marsilea drummondii

Common nardoo

Aquatic fern; fronds with four leaflets; spores in hairy capsules at ground level

Widespread on floodplains in inland regions of eastern states and in coastal subtropical western Australia

Sheep, horses

Thiaminase—polioencephalomalacia in sheep; "bracken staggers" in horses.

The plant contains 100 times more thiaminase than bracken. Poisoning occurs when stock graze dried floodplains dominated by nardoo. IV thiamine (vitamin B₁) is effective in many cases.

*Medicago spp

Medics, lucerne

Herbs with trifoliate leaves and small, yellow or bluish, pea-type flowers, followed by twisted seed pods

Subtropical and temperate regions in all states

Ruminants

Unidentified photosensitizing toxin. Phytoestrogens—infertility (rare).

No effective treatment is known.

Melia azedarach australasica

(M dubia)

White cedar, chinaberry

Deciduous tree with bipinnate compound leaves, sprays of lilac flowers, followed by clusters of oval, dull yellow fruits becoming brown, fleshy, and indented when ripe (drupes)

Native to tropical and subtropical rainforest; cultivated garden plant, street and shade tree

Pigs

Tetranortriterpenes (triterpene; epoxide meliatoxins) cause severe gastroenteritis (low dose); neurologic effects (high dose).

Fruits (drupes) and flowers are most toxic parts implicated. Estimated toxic dose for pigs is 200g; 800g for sheep/goats. Some individual trees are nontoxic. No effective treatment is known.

*Mesembryanthemum spp

Ice plants

Succulent prostrate herbs

Cultivated in gardens; naturalized in southwestern Australia

Ruminants

Soluble oxalates— hypocalcemia, nephrosis.

Toxicity is most likely from rapid, large plant intake, eg, by hungry animals. Soluble oxalates: calcium borogluconate injection (prognosis guarded).

Morinda reticulata

Mapoon, adaa

(Aboriginal names not commonly known)

Shrub with stems either self-supporting or scrambling over adjacent plants, with leathery, opposite-paired leaves and groups of small flowers with a prominent, large, white, leaf-like bract immediately below

Open woodland of Cape York peninsula

Horses

Selenium as selenoamino acids—hair loss from mane and tail, lameness with cracking and shedding of hooves in severe cases.

Edible young shoots after spring under-forest burn. No effective treatment is known. Supplement feeding for horses, thereby reducing plant intake.

Neobassia proceriflora

Soda bush

Annual, upright, many-branched, small shrub with red-striped stems and short, blue-green, succulent leaves

Inland areas of eastern and central states

Ruminants

Soluble oxalates—hypocalcemia, nephrosis.

Toxicity is most likely from rapid, large plant intake. Soluble oxalates: calcium borogluconate injection (prognosis guarded).

Neptunia amplexicaulis

Selenium weed

Prostrate herb with compound leaves, with a leaf-like, heart-shaped stipule at the junction of leaf stalk and stem and with small, yellow, globular flowers on stiff stalks, followed by clusters of dark-brown seed pods

Native to Richmond-Hughenden area of northern Queensland (seleniferous soils)

Horses, ruminants (rare)

Selenium as selenoamino acids—hair loss from mane and tail; lameness, with cracking and shedding of hooves in severe cases.

No effective treatment is known. High soil selenium indicator plant.

Nicotiana spp

Native tobaccos (Nicotiana suaveolens)

21 species (19 native; 2 naturalized)

Erect, annual herbs with soft, dull, green leaves and tall flower spikes with tubular white/cream or pale green flowers, followed by thin-walled pods

Mostly inland regions of all mainland states

Ruminants

Pyridine alkaloids; nicotine causing incoordination, muscle tremors, dilated pupils (impaired vision), recumbency, clonic seizures, diarrhea, and anabasine (a teratogen).

Similar toxic clinical responses among species. No effective treatment is known. Affected animals left undisturbed often recover.

*Oxalis pes-caprae

(O cernua)

Soursob

Perennial prostrate herb with trifoliate spotted leaves and clusters of bright yellow, tubular, five-petalled flowers on stalks

Widespread weed of pasture and cultivation in temperate areas

Ruminants

Soluble oxalates—hypocalcemia, nephrosis. Longterm intake causes chronic nephrosis and kidney failure.

Toxicity is most likely from rapid, large plant intake. Soluble oxalates: calcium borogluconate injection (prognosis guarded). No effective treatment is known for chronic toxicity.

Panicum spp

(There are ~30 native and ~10 introduced species in Australia)

Grasses, tufted with open seed heads, with spikelets attached on individual stalks

Native and naturalized pasture grasses, tropical to temperate regions

Ruminants, horses

Steroidal saponins cause hepatogenous photosensitization in ruminants. Calcium oxalate crystals deny calcium to horses, producing nutritional secondary hyperparathyroidism (lameness, weight loss, jaw swelling).

Supportive treatment for photosensitization (shade, anti-inflammatory, rehydration). No specific treatment available. Calcium oxalate (horses)—remove from the pasture and remineralize bones by feeding a mineral supplement with a Ca:P ratio of 2:1.

*Paspalum spp

Grasses, tufted with erect branched seedhead

Cultivated tropical to subtropical pasture grass

Ruminants, horses

Paspalitrems from Claviceps paspali ergots in seedheads—muscular tremors and incoordination.

The clinical syndrome is reversible if affected animals are removed from ergotized pasture.

*Pennisetum clandestinum

Kikuyu grass

Grass, creeping, forming a dense sward and with very inconspicuous flowers/seeds

Cultivated tropical to subtropical pasture grass

Ruminants, horses, pigs

Unidentified toxin causes upper alimentary tract distension and irritation and nephrosis ("kikuyu poisoning") in ruminants. Soluble oxalate—calcium oxalate crystals deny calcium to horses, producing nutritional secondary hyperparathyroidism (lameness, weight loss, jaw swelling). Nitrate—variable concentrations, methemoglobinemia.

"Kikuyu poisoning"; predisposing factors are poorly understood, but believed to be stressors such as drought and insect attack. No effective treatment is known. There is a high case fatality rate. Calcium oxalate (horses): remove from the pasture and remineralize bones by feeding a mineral supplement with a Ca:P ratio of 2:1.

*Persicaria spp

Polygonum spp

Smart weeds

(16 species reported in Australia)

Herbs with soft leaves and tubular stipules clasping the stem where leaves join; spikes or pink flowers

Weeds of waterway and reservoir margins in eastern states

Ruminants

Unidentified toxin causing photosensitization.

Supportive treatment for photosensitization (shade, anti-inflammatory, rehydration). No specific treatment available. Deny further access to plants.

*Phalaris aquatica

(P tuberosa)

Australian phalaris, Toowoomba canary grass

Grass, clumped with a compact cylindrical seedhead

Cultivated temperate pasture grass

Ruminants

Indole alkaloids causing "phalaris staggers," with hyperexcitability, muscle tremors, and paresis.

No specific effective treatment is available. Prevent by dosing with slow-release cobalt preparations (cobalt bullets) before grazing.

Pimelea trichostachya, P simplex, P elongata

Flaxweeds

Upright annual herbs with opposite leaves on multiple branches, each ending in a flower spike carrying numerous, flask-shaped, green or yellow-green flowers; hairy to different extents depending on species

In dense populations in disturbed habitats in inland northeastern regions

Cattle

Simplexin (irritant diterpenoid) causes a unique syndrome in cattle only consisting of chronic right-side heart failure, anemia, and persistent diarrhea. If other animal species are forced to eat the plants (a very rare occurrence), only diarrhea occurs.

Plants are very unpalatable. Ingestion normally occurs after the plants die and their fragments contaminate other pasture components. Poisoning cases are most likely after above-average winter rains promote dense growth of the plants and then below-average rains in the following summer allow dry plant fragments to remain on pasture. No effective treatment is known.

Polypogon monspeliensis

Annual beard grass

Grass, tufted with compact cylindrical seedheads

Coastal and inland areas of subtropical and temperate regions; seasonally flooded areas

Ruminants, horses

Corynetoxins (tunicaminyluracils produced by Rathayibacter toxicus bacteria in seedhead nematode galls) cause "Stewart range syndrome" with convulsions and death in most cases.

Corynetoxins: a cyclodextrin toxin binding agent is under development as an antidote.

Portulaca oleracea

Pigweed, nland pigweed, munyeroo

Prostrate succulent herb with thick-branched brown or red stems and wedge-shaped leaves and yellow flowers

Widespread native weed of cultivation and disturbed habitats, including stockyards

Ruminants

Soluble oxalates— hypocalcemia, nephrosis. Nitrates—methemoglobinemia. Cyanogenitic glycosides—identified, toxicity not established.

Most poisonings are of hungry animals with access to lush plants in stockyards. Soluble oxalates: calcium borogluconate injection (prognosis guarded). Nitrates: IV methylene blue.

Pteridium esculentum

Austral bracken

Perennial, robust, large fern; rhizomes, simple fronds, each with many narrow subdivisions, glossy (upper) paler (under) surfaces with recurved brown spore-bearing margins

Coastal and subcoastal regions; native to open forests; weed of pasture

Cattle, horses

Ptaquiloside—thrombocytopenia and neutropenia resulting in widespread hemorrhage and terminal septicemia; chronic intake (> 2 years) is associated with urinary bladder neoplasia and chronic hematuria in cattle (rarely in sheep). Unidentified bone marrow toxin— prunasin— cyanide toxicity; Thiaminase—"bracken staggers" (ataxia and cardiac dysfunction) in horses (rare).

Young fronds are the most toxic part of the plant. Toxin retained on drying. Toxicity on chronic exposure. Ptaquiloside: no effective treatment is known. "Bracken staggers" of horses: IV thiamine (vitamin B₁).

*Raphanus raphanistrum

Wild radish

Herb with coarse rosette of leaves at ground level and branched flowering stems with four-petalled, white, yellow, or pink flowers

Widespread weed of cultivation in temperate areas

Ruminants

Unknown, possible S-methylcysteine sulfoxide (SMCO)—hemolysis.

SMCO: ­no effective treatment is known.

*Rapistrum rugosum

Turnip weed

Herb with coarse rosette of leaves at ground level and branched flowering stems with four-petalled yellow flowers

Widespread weed of cultivation

Ruminants

SMCO—hemolysis. Probably sulfur—polioencephalomalacia.

SMCO: no effective treatment is known. Polioencephalomalacia: thiamine may not be effective.

Rhodomyrtus macrocarpa

Finger cherry, native loquat, wannakai

Shrub or small tree with opposite broad leaves carrying oil glands, white five-petalled flowers, followed by fleshy cylindrical globular to oblong red fruit

Rainforests of northeastern Queensland

Ruminants, humans

Unidentified toxin causes permanent blindness from optic nerve degeneration. Rhodomyrtoxin, a benzofuran compound, and saponin have been isolated; toxicity of either not demonstrated.

Leaves and fruits have poisoned ruminants; fruits poison humans. No effective treatment is known.

*Rumex spp

Docks

*Acetosella vulgaris

Sheep sorrel

Herbs with rosettes of broad leaves and tall branched flowering stems carrying green to red flowers and seed pods

Weeds of temperate pasture mostly in southeastern states

Ruminants

Soluble oxalates—hypocalcemia, nephrosis.

Toxicity is most likely from rapid, large plant intake. Soluble oxalates: calcium borogluconate injection (prognosis guarded).

Salsola kali

Soft roly-poly

buck bush, Russian thistle

Annual upright herb with gray-green succulent leaves and dry fruits with a circular, papery wing

Widespread weed of all mainland states

Ruminants

Soluble oxalates—hypocalcemia, nephrosis.

Toxicity is most likely from rapid, large plant intake. Soluble oxalates: calcium borogluconate injection (prognosis guarded).

*Salvia reflexa

Mint weed

wild mint

Erect herb with square stems and blue-green leaves with felty hairs and pale blue tubular flowers in opposite pairs along stems

Widespread weed in inland Queensland and New South Wales

Ruminants

Nitrates—methemoglobinemia.

Toxicity is most likely from rapid, large plant intake. Plants contaminating hay can cause poisoning. Nitrates: IV methylene blue.

Sarcostemma australe

Caustic vine, caustic bush, pencil caustic

Leafless gray-green succulent shrub or scrambling vine with small bunches of waxy white flowers and long pods with milky sap

Widespread in northern areas, both coastal and inland

Cattle, sheep, horses

Unidentified neurotoxin, suspected to be similar to cynanchoside—collapse, clonic convulsions.

No effective treatment is known.

Schoenus asperocarpus

Poison sedge

Grass-like tussock of thin leaves with flower spikes extending above the leaves and bearing flowers (spikelets) in a zigzag arrangement surrounded by broad, brown, square-tipped bracts

Southwestern Australia

Ruminants

Unknown. Galegine—acute pulmonary edema.

No effective treatment is known. Most toxic after rain or burning, restrict exposure during such times.

*Senecio jacobaea

Ragwort

Erect herb with finely divided leaves and bright yellow, daisy-type flowers in clusters at the top of the plant

Weed of pasture and cultivation in southern regions

Cattle, horses

Probably Pyrrolizidine alkaloids—chronic hepatopathy causing mostly weight loss, irritability, and compulsive walking (horses) or weight loss and persistent diarrhea with tenesmus (cattle).

No effective treatment is known.

Senecio linearifolius

Fireweed

Erect shrub with long, pointed leaves and flower heads in bunches resembling those of ragwort

Coastal and subcoastal New South Wales, Victoria, and Tasmania

Cattle, horses

Probably pyrrolizidine alkaloids—chronic hepatopathy causing mostly weight loss, irritability (horses), or weight loss and persistent diarrhea with tenesmus (cattle).

No effective treatment is known.

Senecio lautus

Fireweed, variable groundsel

Erect herb with leaves either simple or with dissected edges and clusters of yellow, daisy-type flowers

Widespread south of 20°S latitude on heavy clay soils

Cattle, horses

Pyrrolizidine alkaloids—chronic hepatopathy causing mostly weight loss, irritability, and compulsive walking (horses) or weight loss and persistent diarrhea with tenesmus (cattle).

No effective treatment is known.

*Senecio madagascariensis

Fireweed

Very similar to Senecio lautus and distinguished by 20-21 bracts under the flower head compared with 11-14 in Senecio lautus

Naturalized in eastern coastal subtropical and temperate regions

Cattle, horses

Pyrrolizidine alkaloids—chronic hepatopathy causing mostly weight loss, irritability, and compulsive walking (horses) or weight loss and persistent diarrhea with tenesmus (cattle).

No effective treatment is known.

Senecio quadridentatus

(Erechtites quadridentata)

Cotton fireweed

Erect herb with narrow leaves covered in cottony hair and with bunches of small, slender flower heads at the top of the stems

Weed of pasture and cultivation in southeastern regions

Cattle, horses

Pyrrolizidine alkaloids—chronic hepatopathy causing mostly weight loss, irritability, and compulsive walking (horses) or weight loss and persistent diarrhea with tenesmus (cattle)

No effective treatment is known.

*Senna occidentalis

Coffee senna

*S obtusifolia

Sickle pod

Small shrubs with compound leaves and clusters of open yellow flowers and flat, long or curved seed pods

Naturalized in northern coastal and subcoastal Australia

Ruminants

Unidentified toxin causing striated muscle degeneration and necrosis with myoglobinuria.

Seeds and seed pods are the most toxic. No effective treatment is known.

*Setaria anceps (S trinervia, S sphacelata)

Setaria

Grass, tall, tufted with a long, compact cylindrical seedhead

Cultivated tropical pasture grass

Ruminants, horses

Soluble oxalates—hypocalcemia, nephrosis in ruminants, very rarely horses. Calcium oxalate crystals deny calcium to horses, producing nutritional secondary hyperparathyroidism (lameness, weight loss, head swelling).

Toxicity from soluble oxalates is most likely from rapid, large plant intake. Soluble oxalates: calcium borogluconate injection (prognosis guarded). Calcium oxalate (horses): remove from the pasture and remineralize bones by feeding a mineral supplement with a Ca:P ratio of 2:1.

*Silybum marianum

Variegated thistle, milk thistle

Annual/biennial herb with broad green and white leaves edged with small, yellow spines, and pink, thistle-type flower heads

Naturalized weed of cultivation in southern and eastern regions

Ruminants, sheep most common

Nitrates—methemoglobinemia sudden death.

Toxicity is most likely from rapid, large plant intake. Nitrates: IV methylene blue.

Solanum spp

Nightshades, potato weeds

Annual herbs to large soft-wood shrubs with star-shaped, five-petalled white or purple flowers with prominent, erect, yellow staminodes centrally, followed by fleshy green, black, yellow, or red fruit

Widespread throughout all states; some as weeds of pasture or cultivation

Ruminants

Intact glycosidic steroidal alkaloids (leaves and immature fruits) cause gastroenteritis with diarrhea, calcinosis, and wasting. Alkamine—neuromuscular and/or teratogenic effects. They are poorly absorbed; however, if absorption occurs, hemolysis (hemoglobinuria), depression, and stupor may occur.

100 species (8 native, 20 naturalized). No specific effective treatment is known.

*Stachys arvensis

Stagger weed

Erect, annual herb up to 30 cm high, with opposite, round-lobed leaves on square stems and tubular pinkish flowers

Widespread weed of cultivation

Ruminants, horses

Unidentified toxin causing incoordination.

Seed carrying plants are more toxic. Removing access to plants and leaving undisturbed results in recovery in most cases.

Stemodia kingii

Erect herb with pale blue tubular flowers

Inland regions of Western Australia

Ruminants

Cucurbitacins—irritation of the upper GI tract and increased permeability of blood vessels producing sudden death with diarrhea.

No effective treatment is known.

Stypandra glauca (S imbricata)

Blind grass

Erect perennial herb with grass-like green leaves and terminal flower heads with pendulous, six-petalled blue flowers with six prominent yellow anthers

Mostly in southwestern Australia with populations in New South Wales

Ruminants, horses, poultry

Unknown. Stypandrol (young green shoots)—degeneration of retina and optic nerves and tracts causing permanent blindness.

No effective treatment is known.

Swainsona spp

Darling or Swainson peas, poison pea

Herbs with compound leaves with many leaflets and usually large, showy pea-type flowers with blue, pink, purple, or red petals, followed by inflated seed pods

Subtropical and temperate regions in all states

Ruminants (cattle more than sheep), horses; Young are more susceptible.

Swainsonine (an indolizidine alkaloid) produces acquired lysosomal storage of mannose, leading to incoordination, nervous derangement, weight loss, infertility, abortion.

Animals are reputed to develop a craving for the plants. Toxicity requires access for at least 2 weeks (horses) or 4 weeks (ruminants). No effective treatment is known. Less severely affected animals recover if access is prevented.

Terminalia oblongata

Yellow wood

Deciduous tree, up to 8–12 m tall, with dark gray, furrowed bark, leaves simple in clusters on branches, small white flowers, and fruits with a central oval seed enclosed in two papery wings

Confined to the McKenzie River basin of northeastern Queensland

Cattle, sheep

Hydrolyzable tannins; cattle—hepatogenous photosensitization and/or nephrosis; sheep—convulsions.

Toxicity is most likely from large plant intake. No effective treatment is known.

*Trachyandra divaricata

Branched onion weed

Herb with rosette of fleshy green linear leaves and an erect dichotomously branched flower spike with numerous darkly striped white flowers

Naturalized in coastal southwestern Australia; small populations also in New South Wales and South Australia

Horses, sheep

Unknown toxin causing ataxia and recumbency with degeneration of CNS tissues and intense lipofuscinosis of neurons.

No effective treatment is known.

Trachymene glaucifolia, T ochracea, T cyanantha

Wild parsnips

Annual or biennial herbs with rosettes of divided leaves at ground level and upright flowering stems bearing clusters of small flowers in flat-topped bunches

Subtropical inland areas of eastern states, in grasslands or woodlands

Sheep

Unidentified teratogenic toxin causing limb deviations via interference with normal development of long bone growth plates—"bent-leg" of lambs. Some association with infertility (low lambing percentages). Unidentified toxin causing sudden death in sheep under stress of mustering. Unidentified toxin causing diarrhea in young sheep.

No effective treatment is known. Many lambs affected at birth will recover.

Trema tomentosa

Poison peach

Small tree with alternate leaves tapered at each end with toothed margins and rough texture, very small white flowers in clusters in the leaf angles, followed by small black fruits

Coastal and inland northern and eastern Australia

Ruminants, horses

Unidentified hepatotoxin causes acute coagulation necrosis of periacinar hepatocytes, with rapid death after hepatoencephalopathy in some cases.

No effective treatment is known.

Trianthema spp (T triquetra)

Red spinach, hogweed, black or giant pigweed

(Several native, one naturalized species)

Succulent prostrate herbs

Widespread in semiarid and arid regions of northern Australia

Ruminants; horses (suspected)

Soluble oxalates— hypocalcemia, nephrosis. Nitrates—methemoglobinemia. Not readily eaten when green.

Toxicity is most likely from rapid, large plant intake. Soluble oxalates: calcium borogluconate injection (prognosis guarded). Nitrates: IV methylene blue.

*Tribulus terrestris

Caltrop, puncture vine, bull head, or cathead

Prostrate annual herb with branching stems and compound leaves with yellow, five-petalled flowers and spiny burrs

Widespread in all mainland states; weed of pasture

Sheep

Steroidal saponins cause hepatogenous photosensitization. Beta-carboline alkaloids cause progressive irreversible caudal ataxia. Nitrate and/or a mycotoxin are suspects.

Toxicity is most likely when the plant dominates available feed. Wilting is thought to enhance toxicity by steroidal saponins. No effective treatment is known.

*Trifolium spp

Clovers

(~20 naturalized species)

Herbs with trifoliate leaves and tight clusters of pea-type flowers with white, yellow, or pink petals

Cultivated pasture legumes in temperate regions

Sheep

Unidentified photosensitizing toxin. Phytoestrogens—infertility

No effective treatment is known.

*Urochloa panicoides

Urochloa, liverseed grass

Annual grass, prostrate or erect, with hairy leaves and branched seedheads

Native to India, naturalized in Queensland and New South Wales

Ruminants

Nitrates—methemoglobinemia.

Toxicity is most likely from rapid, large plant intake. Nitrates: IV methylene blue.

*Verbesina encelioides

Crownbeard, wild sunflower, American dogweed

Erect, annual herb with stem-clasping leaves and bright yellow, daisy-type flower heads

Weed of pasture in eastern regions; prefers sandy soils

Ruminants (sheep more susceptible), pigs

Galegine—acute pulmonary edema. Sudden death.

Toxicity is most likely from rapid, large plant intake. No effective treatment is known.

*Vicia spp

Woolly-pod vetch, Popany vetch

Herbs with compound leaves ending in tendrils and pink or purple pea-type flowers

Pasture legume in subtropical and temperate regions in all states (mainly southeastern Queensland)

Cattle (usually Aberdeen Angus, Friesian, and their cross-breeds); horses (rare).

Unidentified toxin can produce systemic eosinophilic granulomas in multiple organs.

Toxicity occurs when grazing dense swards of the plants. Skin lesions must be differentiated from photosensitization. No effective treatment is known.

Wedelia asperrima

Yellow daisy, sunflower daisy

Erect, annual herb with branched stems, leaves rough to the touch, and yellow, daisy-type flower heads

Grasslands of northern Australia

Ruminants

Diterpenoid (kaurene) glycoside—wedeloside—causes acute coagulation necrosis of periacinar hepatocytes with rapid death after hepatoencephalopathy in some cases.

Toxicity is most likely from rapid, large plant intake. No effective treatment is known.

Wikstroemia indica

Tie bush

Shrub up to 1–2 m tall, with red-brown bark, opposite leaves tapered at each end, greenish-yellow tubular flowers followed by red or orange fleshy fruits

Woodlands and forests of coastal eastern Australia

Cattle, deer

Uncertain. Irritant diterpenoid—alimentary tract irritation, diarrhea. Dicoumarin derivative—anticoagulant effect occurs only in deer. Toxicity–-fruits > leaves.

No effective treatment is known.

*Xanthium occidentale (X pungens)

Noogoora burr, cat's eggs

Upright, annual herb, with branches carrying broad-lobed, rough leaves on stalks, clusters of oblong brown burrs covered with hooked spines

Widespread weed of cultivation and pasture. Queensland and Northern Territory

Ruminants, pigs

Diterpenoid (kaurene) glycoside—carboxyatractyloside—causes acute coagulation necrosis of periacinar hepatocytes with rapid death after hepatoencephalopathy in some cases.

Only the cotyledonary (seed) leaves or burrs are toxic. Toxicity occurs commonly on river flats after rain or flooding. No effective treatment is known.

Xanthorrhoea johnsonii, Xanthorrhoea fulva

Northern Forest grass tree

Perennial rosette of numerous grass-like leaves arising from a trunk (caudex) constructed of leaf bases of fallen leaves, with a tall flower spike with a long cylindrical compact mass of flowers and bracts. Xanthorrhoea fulva does not develop a caudex

Coastal and subcoastal regions of eastern Australia (Queensland and New South Wales)

Cattle

Unidentified toxin—transient spinal cord dysfunction causing caudal ataxia and urinary incontinence.

Flower spikes and leaves are the most toxic parts of the plants. There may be a delay of several days between last access to the plants and onset of the syndrome. Supportive care is required. Most affected animals recover completely with symptomatic treatment.

*Zantedeschia aethiopica

Calla lily, arum lily, white arum lily

Herb with dark-green, fleshy leaves and upright, white, tubular flower (spathe) with yellow stalk (spadix) in its center

Cultivated garden plant, naturalized in coastal southern (particularly southwestern) Australia

Ruminants, horses, dogs, cats

Raphide calcium oxalate crystals—buccal irritation.

Effects are likely to be transient and not need treatment unless laryngeal edema occurs.

*Zea may

Maize

Corn, Indian corn

Grass, erect, robust

Cultivated grain crop

Ruminants

Nitrates—methemoglobinemia. Cyanogenic glycosides—sudden death.

Nitrates: IV methylene blue. Cyanogenic glycosides: IV sodium thiosulfate. Repeat treatment may be needed for relapses.

Zieria arborescens

Stinkwood

Shrub to tree with trifoliate leaves and bunches of small, white flowers

Forests of southeastern mainland and Tasmania

Cattle

Unidentified pneumotoxin causing severe pulmonary edema and emphysema.

No effective treatment is known.