Do you know what is growing in your own back yard? Hungry or grazing animals may be the first to discover potentially poisonous plants growing around the sandbox and under your patio umbrella. Some of these common poisonous plants may be at work around your home:

• In certain circumstances, Alfalfa (Medicago sativa L.) can cause toxic reactions in animals including digestion problems, infertility, and interference with growth.
• Buttercups (Ranunculus spp.) are poisonous when digested while growing in an area of moisture. Grazing livestock, particularly cows, are especially susceptible. Dried buttercups, often mixed with bales of hay, are not poisonous.
• Alsike Clover (Trifolium hybridum L.), are common foraging plants that cause poisoning through ingestion of leaves covered with dew or other moisture.
• Daffodil (Narcissus spp.) causes toxicity to cats, dogs, and horses. The daffodil bulb is the most toxic part of the plant, and may cause gastrointestinal and nervous system problems, abnormal heart functions, and convulsions.
• Bracken Fern (Pteridium aquilinum L.) poisoning affects mainly livestock, domesticated animals, and wild animals, as it is a very popular foliage plant and one of the world’s most successfully growing weeds. Ingestion may cause acute thiamine deficiency and serious illness. Ferns may even be toxic when ingested by humans.
• The prickly Horse Nettle (Solanum carolinense L.) is commonly found in pastures and cultivated land. It contains solanine, a violently toxic chemical that can lead to fatality in people and animals when ingested.
• Lily-of-the-Valley (Convallaria majalis) has potentially toxic properties. It has long been used in essential oils as an herbal supplement to treat heart conditions. Ingestion of large amounts can be toxic to humans and domesticated animals.
• The juice of the Common Milkweed (Asclepias syriaca L.) contains complex compounds that are known to be poisonous. Consumption of large quantities of Milkweed can be toxic to all animals.
• The aromatic Purple Mint (Perilla frutescens), often tinged with purple, contains toxic compounds which adversely affect the lungs of livestock after ingestion.
• Nightshade (Solanum spp.) is toxic to dogs, cats and horses. Consumption may result in intestinal and cardiovascular problems, weakness, difficulty breathing, and fatality.
• Oleander (Nerium oleander L.) is one of the world’s most poisonous plants. Its high toxicity can be fatal to humans and to all animals, even after ingesting just one leaf.
• Poison Ivy (Toxicodendron radicans (L.) Kuntze), is a well-known skin irritant in humans. Although animals generally do not have the same skin reaction to its poison, Poison Ivy can be toxic if ingested.
• The Rhododendron (Rhododendron spp.) plant contains toxins that are extremely toxic to all animals, and may be fatal.
• Rhubarb (Rheum rhaponticum L.) contains highly poisonous toxins in its leaf blades. Humans and livestock are susceptible to serious illness and fatality if even a small amount of the leaf is ingested.
• Tulip (Tulipa spp.) bulbs are especially harmful to animals if swallowed. The toxins commonly cause gastrointestinal distress, central nervous system depression, cardiovascular problems, and convulsions.
• Water Hemlock (Cicuta maculata L.) is the most poisonous plant in North America. Humans and animals alike are susceptible to poisoning and death if consumption occurs.

The following resources outline common plants that are toxic to animals:

The Merck Veterinary Hospital provides comprehensive information on poisonous houseplants and ornamental plants and flowers.

The Humane Society  of the United States lists common poisonous plants.

Cornell University ’s Department of Animal Science provides a searchable database of plants that are toxic to animals

Max’s House has a toxic plant index which outlines signs and symptoms of animal poisoning

It is important to be vigilant of toxic plants or weeds that me growing in your own backyard. Research and vigilance can help prevent the poisoning of family and pets. Danger can be lying in wait in the form of a beautiful flower growing under that (sunbrella). The American Society for the Prevention of Cruelty to Animals (ASPCA) staffs an Animal Poison Control Center for help if your pet ingests a poisonous substance.