https://www.fda.gov/animal-vet...

i am totally baffled at this, I have always thought that day lilies were edible and were not a threat to cats or dogs or people if they are eaten. I know that LILIES are poison, but I am asking about Hemerocallis

Many people feel this is a case of mistaken identity. There have been no actual tests with daylilies that I'm aware of so there is no proof either way. It's quite common on other daylily forums to see pics of Lilium labeled daylily, or commonly day lily, and people calling daylilies lilies either because they don't know they're not, or as a kind of slang, so it's easy to think its a mistake but we can't say for sure.

See:

The thread "Cats and Daylilies - survey results" in Daylilies forum

Mostly it's cats that are implicated but I have seen some web pages extrapolate to dogs but the original veterinary articles did not mention dogs.

I constantly have people who visit my garden or communicate with me about daylilies, call them lilies. It drives me crazy and I do correct them, but it doesn't seem to sink in and they continue to call them lilies!

Everyone who grows daylilies should be aware that although eating the flowers is common practice and has been the case for a very long time, eating other parts of daylilies is not necessarily safe and may cause people to die.

Daylilies, and some plant species that are closely related to daylilies, can contain a toxin that is dangerous to people and some animals.

Some people in China who have eaten daylily roots have died. Daylily roots can contain the toxin, called hemerocallin originally but now known as stypandrol.

See "STRUCTURE AND DISTRIBUTION OF A NEUROTOXIC PRINCIPLE, HEMEROCALLIN" in Phytochemistry Vol. 28, No.7. pp. 1825-1826, 1989.

Currently, it is not known why the roots (in particular) sometimes contain the toxin and sometimes do not.

Yes it has been very ingrained in people that daylilies are lilies, and well I guess the name is confusing in that way. You can't tell people they are not actually lilies they don't listen. The term 'tiger lily' for instance, most people are referring to the old ditch lilies -again pertaining to a plant that isn't a lily at all. To me a tiger lily is the ones on the thick heavy stalks and the blooms have black spots on them. Anyway it just came as a surprise to me that they can make cats sick, and I didn't know they have made some people sick either. I have grown probably over 1000 different daylilies in the past 25 years and had dozens of cats and dogs come and go, and never once had any incident. So poison or not, the pets seem to leave them alone. One thing I can say with certain faith, they are unfortunately perfectly nutritious for deer

Frillylily said:One thing I can say with certain faith, they are unfortunately perfectly nutritious for deer

I can vouch for that, also - leaves, scapes, flower buds and seed pods.