Bulbs, Corms, Tubers and Rhizomes: What Potential Toxins Are Lurking Below the Soil?
Springtime flowers are beautiful, but some are potentially dangerous to our pets. The “bulb” plants can be toxic. Botanically speaking, flower bulbs come in many forms: true bulbs, corms, tubers, tuberous roots and rhizomes. With some bulb plants, only the part below the ground is problematic; with others, it is the whole plant. The plants discussed in this article are toxic to both dogs and cats unless otherwise specified (some are toxic only to cats), but keep in mind that just about any plant material, even grass, can cause mild stomach upset if eaten and a pet is sensitive to it.
True BulbsMost true bulbs have a papery skin and look similar to an onion. These are plants like daffodils (Narcissus sp.), tulips (Tulipa sp.), hyacinths (Hyacinthus sp., Muscari sp.) and snowdrops (Galanthus sp.). These plants contain compounds that are irritating to the gastrointestinal tract. Ingestion of the leaves, stems and flowers (i.e., the above-ground parts) may cause mild stomach upset, while ingesting the bulbs can cause bloody vomiting and diarrhea.
Lilies (Lilium sp.) are true bulbs without the papery skin. All parts of the lily are potentially deadly to cats, as they can cause vomiting and kidney failure. Examples include Easter lily (Lilium longiflorum), Oriental lily (Lilium orientalis) and Japanese lily (Lilium speciosum).
CormsCorms look very similar to true bulbs but are missing the onion-like rings when cut open. Corms are a bulb-like organ that stores the food needed to produce the flower. Common corm plants include: crocosmia (Crocosmia sp.), gladiolus (Gladiolus sp.), freesia (Freesia sp.) and crocus (Crocus sp.). With ingestion of the above-ground parts of these plants, mild gastrointestinal upset can be seen. The corms are more irritating than the above-ground parts and can cause bloody vomiting and diarrhea.
TubersThe tuber plant pet owners may be most familiar with is the potato. Tubers are just enlarged underground stems. Common flowers that grow from tubers include: tuberous begonias (Begonia tuberhybrida), cyclamen (Cyclamen sp.) and anemones (Anemone sp.).
Tuberous begonias contain soluble calcium oxalate crystals with the highest amounts being found in the tuber. In dogs and cats, these crystals can cause vomiting and drooling if ingested. Grazing animals (horses, cattle, etc.) can potentially eat enough to cause kidney failure and death.
Cyclamen plants contain terpenoid saponins. These are soap-like compounds that can cause stomach upset in dogs and cats. Large ingestions of tubers from these plants by grazing animals can cause heart rhythm abnormalities, seizures and death.
Anemones contain protoanemonin throughout the plant including the tuber, which is a blistering compound that can cause pain and sores in the mouth if ingested.
Tuberous RootsTuberous roots are enlarged specialized roots that store food for the growing season. Examples of tuberous root plants are dahlias (Dahlia sp.), daylilies (Hemerocallis sp.) and sweet potatoes (Ipomoea batatas).
Dahlias and sweet potatoes are considered to be nontoxic, but remember just about any plant material can cause mild stomach upset if eaten.
Daylilies are edible for people, but deadly for cats. All parts of the plant can cause vomiting and kidney failure.
RhizomesRhizomes are specialized stems that grow sideways underground, and some are used for food storage for the plant. Common rhizome plants include: iris (Iris sp.), lily of the valley (Convallaria sp.), canna (Canna sp.) and ginger (Zingiber officinale).
Irises contain gastrointestinal irritants that can cause burning in the mouth, gagging, vomiting and diarrhea.
Lilies of the valley are highly toxic plants and contain cardenolides that affect the heart. Ingestion of the plant (even water from the vase) can cause vomiting, low blood pressure, irregular heart rate, seizures and death.
Cannas and ginger are considered to be nontoxic, but again keep in mind that any plant material can cause mild stomach upset.
Whether you are planting bulbs in your yard, forcing them inside or cutting them for bouquets, make sure your pets do not have access to the plants. Prevention is important, especially for bulbs. Make sure to store them in safe places. It is also important to keep the labels that contain the Latin names, just in case your pets do decide to sample some of the plant.
Call your veterinarian if you suspect your pet has eaten any of the potentially toxic plants listed here or is exhibiting gastrointestinal signs such as vomiting or diarrhea.
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