The colorful, low-growing annual known as Moss Rose (Portulaca grandiflora) is a popular garden flower recognized for its ability to thrive in hot, dry conditions. When considering the safety of this plant for people, the answer is reassuring: Moss Rose is generally considered non-toxic or only mildly toxic if accidentally ingested. The risk to human health is minimal, primarily causing only temporary, low-level physical reactions.
Defining the Moss Rose Plant
The Moss Rose is a succulent flowering plant known primarily by its botanical designation, Portulaca grandiflora. It is also frequently referred to as Portulaca, Sun Rose, or Eleven O’Clock because its flowers open only when the sun is bright. As a tender annual, it is cultivated globally for its bright, cup-shaped flowers that bloom in a wide spectrum of colors.
The plant features thick, fleshy, needle-like leaves and reddish stems, growing in a dense, mat-forming habit that makes it a favored ground cover. It is important to distinguish Portulaca grandiflora from its close relative, Portulaca oleracea, commonly known as purslane, which is an edible plant. While both are in the same genus, their uses and chemical compositions differ.
Human Toxicity Status and Symptoms
While Moss Rose is not considered poisonous for humans, its consumption is not recommended and can result in mild physical reactions. The plant contains calcium oxalate crystals, which are a defense mechanism found in many plant species. These oxalates are not present in a concentration high enough to cause severe systemic poisoning.
Ingesting a small amount of the plant may cause minor, localized irritation due to the physical structure of the oxalate crystals. These tiny, sharp structures can irritate the delicate mucous membranes of the mouth, throat, and digestive tract. Symptoms that might occur are typically limited to mild stomach upset, nausea, or a temporary bout of vomiting or diarrhea.
More severe reactions are extremely rare and are usually associated only with ingesting a very large quantity of plant material. Because the plant’s taste is generally unappealing, people rarely consume enough to cause anything more than temporary discomfort. Any reaction is generally short-lived and subsides quickly without lasting effects.
First Aid and When to Contact Poison Control
Immediate action following accidental ingestion should focus on minimizing irritation and observing for symptoms. If any part of the Moss Rose plant was chewed or swallowed, the first step is to rinse the mouth thoroughly with water to remove residual plant material and crystals. Drinking a small amount of water or milk can help soothe the throat and dilute any swallowed material.
Because of the plant’s low toxicity to humans, observation is often the only intervention necessary. You should, however, contact a regional Poison Control Center (PCC) for expert advice, even if symptoms appear mild. The national, toll-free Poison Help Line, 1-800-222-1222, connects callers directly to their local center.
Contacting the PCC is particularly important if a large quantity of the plant was consumed, if the person has a pre-existing health condition, or if symptoms persist or worsen. Specialists in poison information can assess the situation and provide guidance on whether further medical attention is required. In nearly all cases involving Moss Rose, the advice will be for continued observation at home.
Safety for Household Pets
The safety status of Moss Rose changes significantly when considering household pets, particularly dogs and cats. Unlike the minimal risk to humans, Moss Rose is listed by veterinary associations as mildly to moderately toxic. This difference is due to the toxic principle present in the plant: the soluble form of calcium oxalates.
When pets ingest parts of the Moss Rose, the soluble oxalates are absorbed by the gastrointestinal tract and enter the bloodstream. These compounds then bind with systemic calcium, which can lead to a sudden drop in blood calcium levels. While rare, the formation of insoluble calcium oxalate crystals can accumulate in the renal tubules, potentially leading to acute kidney failure in severe cases.
Pet owners should watch for specific clinical signs if they suspect their dog or cat has eaten the plant. Common symptoms include excessive drooling, vomiting, diarrhea, lethargy, and sometimes tremors. If ingestion is suspected, it is advised to contact a veterinarian immediately or call a pet poison control service for guidance. Timely intervention can prevent the progression of symptoms and ensure the pet receives appropriate supportive care.