The caladium (i.e. Caladium bicolor or Caladium esculentum) is a South American tropical plant that has large heart-shaped leaves. They can be green and red, green and white, white with green veins, white with red blotches, and some may have lavender spots. They do well in a warm and moist climate. They are poisonous if any of the plant is consumed orally.
The caladium contains calcium oxalate crystals and asparagine. Both are toxic if large amounts are eaten. They are found throughout the plant and not just concentrated in one location.
Symptoms of poisoning from eating caladium include burning in the mouth and throat, sometimes severe, with nausea, diarrhea, vomiting, swelling of tongue and mouth, redness, swelling, burning, and pain in the eyes.
Call National Poison Control (1-800-222-1222) and emergency personnel while wiping out the mouth with a wet cloth. Give milk to the one poisoned. Once medical personnel arrive they will assess vital signs and look to see if the airway is blocked. They will monitor the patient and treat the symptoms as needed, making sure that there is not life-threatening complications.
This type of poisoning is also called Heart of Jesus plant poisoning, Texas Wonder plant poisoning, Alocasia plant poisoning, Angel wings plant poisoning, Colocasia plant poisoning.
While an attractive houseplant, the caladium is a dangerous plant around pets or people that may chew or ingest their leaves. Always keep a watchful eye or keep it out of reach.
Source: A.D.A.M., Botany.com