11. CASTORBEAN, CASTOR OIL PLANT

Ricinus communis

(spurge family)

TOXICITY RATING: High. Death is likely with consumption of even small amount of castorbean.

ANIMALS AFFECTED: All animals may be affected.

DANGEROUS PARTS OF PLANT: The seeds are the primary source of toxin, but the rest of the plant may be considered to be slightly toxic as well.

CLASS OF SIGNS: Stomach irritation, diarrhea, abdominal pain, increased heart rate, profuse sweating, collapse, convulsions, death.

PLANT DESCRIPTION: This stout, robust shrub-like plant with reddish to purple stems may reach 12 feet in height. A perennial in its native tropics, it is grown as a garden annual in Indiana. The large (4 to 30 inches across), umbrella-like leaves (fig. 11) have 5 to 9 pointed, finger-like lobes. Long purple leaf-stems are attached near the centers of the leaf blades. Greenish-white or reddish-brown flowers are produced in narrow, upright clusters. The fruit is a three-lobed, green or red capsule with a soft, spiny

exterior. One large, mottled, attractive seed (fig. 11A) develops in each lobe. Some people think the seeds look like well-fed ticks.

SIGNS: The phytotoxin ("plant toxin") in castorbean is ricin, a water soluble protein, which is concentrated in the seed. Also present are ricinine, an alkaloid, and an irritant oil. As a side note, commercially prepared castor oil contains none of the toxin. There is great species variability in susceptibility to ricin toxin, with humans and horses being the most at risk (25 grams of castorbean seed is lethal for the horse). Due to the powerful toxin however, it is best to keep all animals (livestock and pets) away from this plant.

The seed is only toxic if the outer shell is broken or chewed open. Seeds swallowed intact usually pass without incident. Signs of toxicity may not manifest for 18 to 24 hours after ingestion. The animal first shows signs of depression and a mild increase in temperature. Later, gastrointestinal signs predominate, including vomiting in humans and other species that can vomit (horses cannot vomit), profuse diarrhea (which may be bloody), colic and abdominal pain. The affected animal may then go into convulsions, collapse and die, with death generally occurring within 36 hours of consumption. The toxic signs are the result of severe gastrointestinal irritation, anaphylaxis and shock. This toxin is closely related to the toxin in rosary pea (a section on this plant is also included in this book).

FIRST AID: If animals are observed eating castorbean, call a veterinarian immediately, since emergency measures need to be undertaken. If consumption occurred several hours ago, a veterinarian will be able to provide supportive care and treat for shock, but death may still result from this powerful toxin.

SAFETY IN PREPARED FEEDS: The seeds may become incorporated into hay or grains. The seeds are never safe to eat, especially by horses or livestock, since these animals could easily crack the seed coat. After making castor oil, the remaining seed cake is sometimes used for animal feed. This needs to be boiled or heated to remove the toxin.

PREVENTION: Do not allow seeds or any other part of the plant to be incorporated into animal feeds. It is advisable to not let castorbean grow in the vicinity of pastures used for grazing or forage production. Do not allow pets access to this plant. To decrease the chances of intoxication, snip off the flower heads before they develop into seeds; this will protect children as well as pets.