This is a copy of a list posted on www.realgardners.co.uk in response to request by me. It's long, but worth having a look at.
"It's pretty difficult to get a list that includes what the effects are, let alone one that is authoritative. I do have such a list, but I can't now remember where it came from and I'm going to preface it with a quote from the BBC Web site:
"Keep risks in perspective - Before you panic and rush off to convert your garden into a Japanese art form of stones and water, keep things in perspective. Research has shown the risk of harm from plant poisons is low - less than one in 10 million, or about the same as the chance of winning the lottery or being struck by lightning. Why not start a weekly walk with your children to show them the beauty and beasts in your garden?"
"And here's the link for the full article, which singles out some of the most dangerous plants in a UK context.
"So now here's my list. Each item in the sequence: plant, toxic part, symptoms. (You're going to be sorry you asked! )
HOUSE PLANTS
Hyacinth, Narcissus, Daffodil
Bulbs
Nausea, vomiting, diarrhea. May be fatal.
Oleander
Leaves, branches
Extremely poisonous. Affects the heart, produces severe digestive upset and has caused death.
Dieffenbachia (Dumb Cane), Elephant Ear
All parts
Intense burning and irritation of the mouth and tongue. Death can occur if base of the tongue swells enough to block the air passage of the throat.
Rosary Pea, Castor Bean
Seeds
Fatal. A single Rosary Pea seed has caused death. One or two Castor Bean seeds are near the lethal dose for adults.
FLOWER GARDEN PLANTS
Larkspur
Young plant, seeds
Digestive upset, nervous excitement, depression. May be fatal.
Monkshood
Fleshy roots
Digestive upset and nervous excitement.
Autumn Crocus, Star of Bethlehem
Bulbs
Vomiting and nervous excitement.
Lily-of-the-Valley
Leaves, flowers
Irregular heart beat and pulse, usually accompanied by digestive upset and mental confusion.
Iris
Underground stems
Severe - but not usually serious - digestive upset.
Foxglove
Leaves
Large amounts cause dangerously irregular heartbeat and pulse, usually digestive upset and mental confusion. May be fatal.
Bleeding Heart
Foliage, roots
May be poisonous in large amounts. Has proved fatal to cattle.
VEGETABLE GARDEN PLANTS
Rhubarb
Leaf blade
Fatal. Large amounts of raw or cooked leaves can cause convulsions, coma, followed rapidly by death.
ORNAMENTAL PLANTS
Daphne
Berries
Fatal. A few berries can kill a child.
Wisteria
Seeds, pods
Mild to severe digestive upset. Many children are poisoned by this plant.
Golden Chain
Bean-like capsules in which the seeds are suspended
Severe poisoning. Excitement, staggering, convulsions and coma. May be fatal.
Laurels, Rhododendrons, Azaleas
All parts
Fatal. Produces nausea and vomiting, depression, difficult breathing, prostration and coma.
Jasmine
Berries
Fatal. Digestive disturbance and nervous symptoms.
Lantana Camara (Red Sage)
Green berries
Fatal. Affects lungs, kidneys, heart and nervous system. Grows in the southern U.S. And in moderate climates.
Yew
Berries, foliage
Fatal. Foliage more toxic than berries. Death is usually sudden without warning symptoms.
TREES AND SHRUBS
Wild and cultivated cherries
Twigs, foliage
Fatal. Contains a compound that releases cyanide when eaten. Gasping, excitement and prostration are common symptoms.
Oaks
Foliage, acorns
Affects kidneys gradually. Symptoms appear only after several days or weeks. Takes a large amount for poisoning.
Elderberry
All parts, especially roots
Children have been poisoned by using pieces of the pithy stems for blowguns. Nausea and digestive upset.
Black Locust
Bark, sprouts, foliage
Children have suffered nausea, weakness and depression after chewing the bark and seeds.
PLANTS IN WOODED AREAS
Jack-in-the-Pulpit
All parts, especially roots
Like Dumb Cane, contains small needle-like crystals of calcium oxalate that cause intense irritation and burning of the mouth and tongue.
Moonseed
Berries
Blue, purple color, resembling wild grapes. May be fatal.
Mayapple
Apple, foliage, roots
Contains at least 16 active toxic principles, primarily in the roots. Children often eat the apple with no ill effects, but several apples may cause diarrhea.
Mistletoe
Berries
Fatal. Both children and adults have died from eating the berries.
PLANTS IN SWAMP OR MOIST AREAS
Water Hemlock
All parts
Fatal. Violent and painful convulsions. A number of people have died from hemlock.
PLANTS IN FIELDS
Buttercups
All parts
Irritant juices may severely injure the digestive system.
Nightshade
All parts, especially the unripened berry
Fatal. Intense digestive disturbance and nervous symptoms.
Poison Hemlock
All parts
Fatal. Resembles a large wild carrot.
Jimson Weed (Thorn Apple)
All parts
Abnormal thirst, distorted sight, delirium, incoherence and coma. Common cause of poisoning. Has proved fatal.