POISONOUS PLANTS IN NEW ZEALAND

New Zealand Journal of Agriculture, Volume 81, Issue 5, 15 November 1950, Page 461

POISONOUS PLANTS IN NEW ZEALAND

'T’HIS is the second section of a series of descriptions of poisonous

plants which grow in New Zealand by

H. E. Connor,

, Botanist,

Department of Scientific and Industrial Research, Wellington. Glossaries to be used with the series' were published with the first section, which appeared in last month’s “Journal”.

DICOTYLEDONS Ranunculaceae Lesser Spearwort. Ranunculus flammula L. (Fig. 2, F and G) Botanical description: Habit Herb with erect or ascending stems. — Basal leaves sheathing, blades elliptic to obovate; upper leaves sheathing, nearly ovate to nearly linear. Flowers— Bright yellow. FruitSwollen and slightly beaked achenes. (Eurasia.) Habitat: Ditches, wet places, and pastures. Distribution: Rather sparingly as far south as Timaru. . General: Lesser spearwort has been suspected of poisoning sheep in Te Awamutu, and in England' has repeatedly proved fatal to horses and cattle. R. flammula is considered to be as toxic as R. sceleratus (celery-leaved buttercup). The toxin is destroyed by drying. Symptoms of poisoning: Irritation of the mucous membrane and inflammation of the intestinal tract. i. Poisonous principle: The toxin in R. flammula is protoanemonin. Creeping Buttercup. Ranunculus repens L. (Fig. 2, D and E) Botanical description: — Herb; rooting at nodes; flowering stems hairy, up to 30in. long. Leaves Leaf blades divided into 3, segments 3-parted, coarsely and deeply toothed. Flowers— Deep yellow. Fruit— Compressed and minutely pitted achenes. (Eurasia and North Africa;) Habitat: Damp pastures and waste places. Distribution: Plentiful throughout New Zealand. General: Doubt exists about the toxicity of this species. Creeping buttercup, like other Ranunculus species, is claimed to be toxic, but it is suggested that “it is scarcely, if at all, injurious”. In the spring of 1942 and 1943 cows were found dead at the Mount Peel Station, and as creeping buttercup was abundant it was suspected as the cause. The post-mortem examination symptoms also suggested Ranunculus poisoning. v Symptoms of poisoning: Post-mortem-Acute inflammation of the small intestine and the abomasum; the blind gut less inflamed. Poisonous principle: Protoanemonin is present in creeping buttercup and is the toxin. Waoriki; Ranunculus rivularis. Banks et Sol. ex D.C. (Fig. 2, A) Botanical description: HabitHerb' stems creeping, often branched ana forming broad, matted patches, rooting at nodes. Leaves—On slender petioles; blades % to l|in. in diameter, ovate, semi-circular or kidney shaped in outline, usually divided 3 to 7 times. Flowers — Yellow, I to fin. in diameter. Fruit turgid achene with a straight or recurved beak. This plant is exceedingly variable. (New Zealand and Australia.) Habitat: Near swamps, creeks, and damp places.

Distribution: Abundant in North, South, and Stewart Islands from sea level to 3000 ft. - \

General: Instances of poisoning are frequently attributed to this plant, which is the most toxic of the known poisonous native species of Ranunculus. Most losses of stock are reported from the northernmost part of the North Island, where cattle are most frequently poisoned. Waoriki has been shown to be lethal when experimentally dosed to sheep. The whole of the plant is toxic and is suspected to be more so in spring. Toxicity is lost on drying. Losses among stock also occur in Australia from this species. Symptoms of poisoning: The antemortem symptom is colic. Post-mortem examination of sheep shows a fair degree of congestion and ulceration of the wall of the rumen and marked ulceration on the wall of the fourth stomach. Inflammation extends down into the small intestine. Poisonous principle: An irritant toxin is present in the plant.' Celery-leaved Buttercup. Ranunculus sceleratus L. (Fig. 2, B and C) Botanical description: Habit—herb with erect stems up to 30in. high. Leaves On long petioles, blades 3lobed. Flowers Petals yellow, a little longer than the reflexed sepals. FruitAchenes, hardly beaked. (Eurasia and North Africa.) Habitat: Ditches and waste places. Distribution: Rather plentiful throughout New Zealand. General: Celery-leaved buttercup is regarded as the _ most toxic of the buttercups, but in New Zealand is not responsible for as many deaths as waoriki. It is poisonous to all stock, though more dangerous to cattle. Celery-leaved buttercup has been suspected of poisoning sheep in the Christchurch district. The whole of the plant is poisonous. The toxin is destroyed on drying, so that celeryleaved buttercup included in hay is non-toxic. Symptoms of poisoning: The first ante-mortem symptoms are those of gastro-enteritis, colic, nausea, vomiting, salivation, blackened faeces, and sometimes haematuria. Symptoms include retardation of pulse, slow and stertorous breathing, difficulty in mastication and drinking, and blindness. If large quantities of the plant are eaten, there may be convulsions; when these occur death usually follows within 12 hours. Post-mortem ■ symptoms consist of inflammatory lesions of the alimentary tract, particularly of the intestines. . Poisonous principle: A volatile, acrid, bitter, irritant substance, protoanemonin, is present in all parts of the plant except the seeds. Polygonaceae Sour Dock. Rumex acetosa L. (Fig. 3, F to I) ? Botanical description: Habit-Herb with stems up to 30in. tall; stipules united to form an elongate tube. Leaves— Oblong, arrow shaped, and rather thick. Flowers Unisexual; enlarged tepals, roundish, heart shaped, and with minute wart-like growths; outer tepals reflexed, (Eurasia.) . Habitat: Waste places and pastures. Distribution: Occasional in both islands.

General: Sour-dock poisoning is not common either in New Zealand or abroad, but isolated losses were reported in New Zealand before 1936. In Canterbury during the spring of 1936 ewes with lambs 5 to 8 weeks old were poisoned by sour dock; about 10 per cent, of the ewes affected died, the others being treated and recovering. Poisoning usually occurs * only in spring and summer. Lactating ewes

POISONOUS PLANTS IN NEW ZEALAND

are especially affected. Symptoms of poisoning result from a reduction of blood calcium caused by its precipitation by soluble oxalates. A solution made by heating 20oz. of calcium gluconate, soz. of boric acid, and lOOoz. of water, given in injections of about 100 c.c., proved effective in the 1936 outbreak. This remedy confirms the type of poisoning. The lambs grazing with the ewes are not affected.

Symptoms of poisoning: The cases referred to show staggering as the first noticeable ante-mortem symptom. If the poisoning is serious, the animals go down and in most cases cannot get up. There is frequently a discharge from the nose. Muscular spasms are 1 common, breathing is abnormal, the animal finally becomes comatose, and unless it is treated death follows. Post-mortem examination shows slight inflammation. Poisonous principle: The toxin is oxalic acid and soluble oxalates. Sheep Sorrel. Rumex acetosella L. (Fig. 3, A to E) Botanical description: Habit Herb with stem up to 15in. tall; united stipules fringed with fine . teeth. Leaves Spear shaped, lanceolate to linear. Unisexual; tepals ovate, hardly enlarged in fruit, appressed to fruit. (Eurasia.) Habitat: Cultivated and waste land, open pastures, and low tussock grassland. Distribution: Abundant throughout both islands.

POISONOUS PLANTS IN NEW ZEALAND

General: Some authors have claimed that the seeds of sheep sorrel are poisonous to horses and sheep. However, in view of the abundance of this species in New Zealand and the apparent absence of known stock losses caused by it, it is considered that poisonings are not to be expected. C h e'nopo diaceae Sugar Beet. Beta vulgaris L. var. altissima D.C. (Fig. 4, D) Mangold. Mangelwurzel. Beta vulgaris L. var. rapa bum. (Fig. 4, A to C) Botanical description: —Annual, glabrous, thick-rooted plants; roots of various colours. Leaves Large, alternate, entire. Flowers Perfect, becoming hardened in fruit. Seeds cohere . into a seed ball. (Europe.) Habitat and distribution: Cultivated crops. General, mangolds: Mangold poisoning is not common in New Zealand, though several cases have been reported. A serious loss occurred on a piggery in Otago where 200 pigs died

after being fed cooked, freshly pulled mangolds. It was shown later that clamped mangolds cooked at a temperature below boiling point or at boiling point for too short a time could also be poisonous. Cooking mangold roots for 2 hours or more at boiling point makes them non-toxic. The suitability of raw, fresh mangolds was not considered in this work, but it is accepted, possibly erroneously, that frosted mangolds are poisonous to stock. In New Zealand cows have been poisoned by eating mangolds.

General, sugar beet: Recorded cases show that sugar-beet pulp can cause poisonings in. cattle. This type of poisoning is not known in New Zealand, but should be considered, as sugar beet is being grown to an increasing extent in the Dominion. Cases are on record of fresh sugar-beet leaves being poisonous to cattle and pigs in Austria and Sweden, where the leaves are commonly fed. Some authors believe that small quantities of leaves will not produce any ill effects in stock, but that larger amounts may cause death. Several authors have advocated the feeding of sugar-beet tops to stock as an accessory fodder. The presence of oxalic acid in the leaves makes the plant a potential danger to stock. Symptoms 'of mangold poisoning: Ante-mortem ln the pig poisonings observed death occurred rapidly, but in a number of cases symptoms of pain were shown. Muscular weakness was followed by laboured respiration, and death ensued from asphyxiation, usually preceded by convulsions. Vomiting occurred in a number of cases. Post-mortem External signs were a cyanotic appearance. of visible mucous membranes and a marked paleness of the skin in the region of the snout and coronets. The viscera showed marked venous dilation of visible mesenteric blood vessels. The liver and kidneys were dark red and congested, the stomach and small intestine had an inflamed .appearance, and the lungs were abnormally red, showing marked venous congestion. The blood was a chocolate colour, resulting from the change of haemoglobin to methaemoglobin. Symptoms of sugar-beet poisoning: Roots Staggers and bloat are the symptoms recorded in bullocks poisoned. Impaction of the stomach and choking is to be expected in cattle and horses. Leaves— sequence of symptoms in pigs is rapid, appearing soon after a meal of leaves has been finished. Apathy, unwillingness to rise, swaying gait, weakness in hindquarters, muscular tremors, spasms, pale grey skin and snout, weak and accelerated heart action, retching, vomiting, and extreme dyspnoea precede death. Cows show depression and diarrhoea, and death occurs if the feeding of leaves is continued. Postmortem examination reveals dark brown to black, tar-like blood; coagulation of the blood is retarded. Poisonous principles 1 of mangolds: Excessive amounts of nitrites are present in the roots after they have been cooked at too low a temperature and then allowed to cool. • Poisonous principles of sugar beet: Roots— The fermentation of the sugar present in the roots is presumed to cause the symptoms of bloat. Leaves— The toxin in the leaves is oxalic acid, and oxalates.