• Eating the stems of an iris plant can cause stomach upset.IRIS image by JP65 from Fotolia.com
  
  Many garden plants are edible and safe for humans to touch or eat. However, some common plants can cause severe reactions, including death, when ingested or touched. Other garden plants will not trigger a reaction in humans, but may be poisonous to animals and pets. Before touching or ingesting a plant you are unfamiliar with, check to be sure it is safe.
  
  

Hyacinth

• Hyacinth causes stomach upset when ingested by humans.
  
  

Larkspur

• The seeds of the larkspur can be fatal if consumed. Larkspur also causes depression and digestive upset in humans.
  
  

Crocus

• Eating a crocus bulb can cause vomiting, oral irritation, organ failure and even death. The crocus is poisonous to both humans and animals.
  
  

Lilies

• The peace lily is poisonous to animals, causing irritation and digestive problems when consumed. The leaves and flowers from the lily of the valley cause similar symptoms in humans, in addition to mental confusion and variable heart rate.
  
  

Rhubarb

• While the stalks of the rhubarb plant are edible, the leaf blades are very dangerous when ingested. Symptoms include vomiting, burning of the skin and mucous membranes, diarrhea and convulsions. Ingesting a large amount of leaves can be fatal.
  
  

Tulip

• Tulip bulbs can cause rashes when exposed to skin and nausea, vomiting and variable heart rate if ingested. Tulips also can be dangerous for animals, causing convulsions, digestive problems and heart issues.
  
  

Foxglove

• Foxglove leaves are poisonous when ingested by humans. Symptoms include gastrointestinal upset, variable heart rate and confusion. Consuming a large amount of foxglove leaves may result in death.
  
  

Tomato

• While the fruit of the tomato is edible, the leaves and vines are poisonous. Consuming the leaves and stalks of a tomato may result in a reduced temperature, digestive upset and headache.
  
  

Oleander

• Oleander is poisonous to both humans and animals. Eating the plant causes severe digestive upset that may lead to death.
  
  

Hydrangea

• Eating part of the hydrangea plant can cause serious symptoms like sweating, digestive upset and pain in the abdomen in both humans and animals.