cardiac glycosides
Flower Color:
  • flower color
fields, woodlands, wasteareas, roadsides, gardens, haybales

Time of Greatest Risk


Geographical Distribution

Summer pheasant's eye distribution - United States

Related Species

Summer Pheasant's Eye

Adonis aestivalis

Red Chamomile, Adonis, Autumn Pheasant's Eye
8/ 10
Summer pheasant's eye (Adonis aestivalis ) is a small herbaceous perennial plant with large buttercup-like blossoms and soft, fern-like leaves. It is native to Europe and Asia, and was introduced to other areas of the world as a garden ornamental. A. aestivalis was introduced into North America initially as a horticultural plant, however it escaped cultivation and now grows in the wild in the western United States (California, Oregon, Washington, Idaho, Montana, and Utah), Missouri, and New York. It grows abundantly in open forests and disturbed sites in the Western states. It also grows in hay fields, and on occasion can get mixed in with hay when baled.
summer pheasants eye horses

Toxic components
All parts of A. aestivalis contains cardiac glycosides, which are cardiotoxic to horses, resulting in fatal digestive and cardiac disturbances. Specific chemicals include adonitoxin, strophanthin, vernadigin, and cymarin. The leaves and flowers have the highest concentration of toxins.

Poisoning cases
In 2004, three horses died from eating grass hay containing A. aestivalis . The hay appeared normal to the naked eye, but most of the 20 horses that were fed the hay refused to eat it. The three horses that died began to show clinical signs of gastrointestinal disturbances and myocardial necrosis after consuming the hay contaminated with A. aestivalis 24-48 hours after they were first exposed.

In a 1952 there were reports of four separate cases in which horses were fed alfalfa hay contaminated with A. aestivalis.