follow this link
(see related link)
the biggest one to look for on your farm though, is ragwort.
yes! they don't know what's poisonous and what's not.
Liquid amber trees are not poisonous to horses. However, there are many trees and plants that are toxic to horses including lemon, lime, and horseweed.
Most of the time, horses will not eat anything poisonous unless they do not have anything better for them to eat. However, some horses are drawn to some poisonous plants. Whether your horse is drawn to them or not, you need to remove all poisonous plants from your horses reach.
Carrots do not make horses blow up. Deadly Nightshade, Carolina Jasmine, and Poke Weed are some of the common poisonous plants in Florida.
There are many things that can be poisonous to horses, plants being the worst offenders. Even though I don't know what plants are exposed to your horse I do know that all horses and ponies are poisonous to the same things. One of them is maple leaves. If your horse eats one it will die. Another thing is chestnuts.(The nuts not the ones on horses legs.)
It is unclear whether or not Ixora plants are toxic to horses. In cases like these it is best to avoid letting horses have contact with the plants until it is fully determined to be toxic or not.
No Hollyhock is Not posionous to horses. Here is a link of poisonous and non-poisonous plants to horses: http://www.aspca.org/pet-care/poison-control/plants/index.jsp?plant_toxicity=non-toxic-to-horses&page=9
Cherry Leaves are poisonous to horses. BE ALERT!
I have been told that the greens of potato palnts are poisonous to horses. I am researching this now and will report back. Yes the green parts of the potato plant are poisonous. The potato is a member of the nightshade family. They contain solanin which is a nerve toxin that is very toxic even in small amounts.
Mountain Ash leaves are not poisonous to horses or other animals. The berries of the Mountain Ash are not poisonous either.
Ragwort is poisonous to horses it is very dangerous
Primroses are in the genus Primula. The ASPCA says the common primrose (Primula vulgaris) is toxic to dogs, cats and horses.