Day Lily - Looks like a cross between the Tiger Lily and something else. No these aren't poisonous. They are actually edible. I never tried them though. I have at least a dozen in my garden and my cat is fine.

This looks like a daylily Hemerocallis. I have these in my garden and my cat is fine.
There are some lilies whose pollen is poisonous to cats.

my eldest girl said they were possibly dangerous. she did a search about this as she has 3 rescue cats.

this vet site said yes Hemerocallis is toxic

https://www.vets-now.com/2017/03/spring-plants-warnings-cat-owners/

I've had cats and hemerocallis for years. Most cats are intelligent fussy eaters.
Many garden plants are poisonous so if this worries you maybe better check out your other plants too. Our member Thepoisongardener would I'm sure be happy to look at a list of your plants to check for you.

My cat never goes near them. English Yew is another story. English Yew is lethal and my cat was drawn to it for the cool shade they provide in the hot months. It was the last thing he did.

Had dozens of Hemerocallis in our last garden and always had cats. Not one of them has ever bother with the Hemerocallis.
It is the pollen from Lilies which is poisonous to cats, so on ours we always remove the stamen from the centre of the flower. It also makes the flower last longer.

It seems that cats getting poisoned is mostly a problem when the plants are inside. I don't know if they assume something inside is OK.

Outside, the key point is that you can't control where your cat goes. You might go to extreme lengths to make sure your garden is 'cat safe' but the cat will go and visit a dozen or more other gardens where you have no idea what plants there are.

Paul how heartbreaking. Did the cat actually eat some yew? You would think it was a bit tough for chewing. Did this happen a long time ago - hope it wasn't the cat you have now?

My cat didn't chew the woody part, just the soft needles. He went into respiratory distress and was gone that night. The veterinarian couldn't save him. It was too much poison.

Furthermore, the plant in question here is Daylily - Hemerocallis and theoretically, all parts of the plant are safe to eat and are not toxic, the roots, the leaves, the flowers and the pollen. This is referring to the wild day lily or Tiger LIly. However, due to the hybridization and cross pollination, I would advise NOT to try eating this plant because there isn't enough confirming information regarding hybrids. This is a Tiger Lily crossed with something else. Who knows what?

This plant is a hybrid so don't try to eat it. However, you should not have to worry about your cat being poisoned. Also, don't fuss about removing the pollen from this. It's a DAY LILY. It will be gone tomorrow regardless.

Lilium polyphyllum is the toxic one to worry about. These grow on a single stalk with lance like leaves with 4 or 5 flowers up at the top. These are the Asiatic Lilies, Easter Lilies and such like (One of these is named 'Tiger Lily' too). That's NOT the one in question here. Definitely do not let your pets near these and don't try eating them yourself.

I know this is a bit confusing, especially because of reclassification and lack of reliable information. No cat I ever had ever went near my day lilies, so you should be fine. Here is an interesting article if you want to explore this topic a bit further. It also sites my source material.

https://delishably.com/foraging/Should-You-Eat-Your-Daylilies

It is puzzling when common names are used for two or more different plants. Hemerocallis may be called Day lilies but they are not even remotely related to true Lilies.

Owd, thank you for this. I was given a pot of Asiatic lilies last year - must remember to remove the stamens next year.

It looks like it is Hemerocallis fulva. My cats chase each other through the clumps, sleep under them, and sometimes sleep on top of them. All with no problems. Vets claim they are poisonous but have no scientific evidence to back it up. I looked at the Vets-now site, and if they are able to confuse Hemerocallis with Lillium, I have to wonder about them. They also confused Amaryllis with Hippeastrum, btw.

Thanks all, thats what i like about the best gardening site on the web,having read all the responses my daughter has decided to be on the safe side and remove the lillies.As i dont have cats and love a freeby ime taking them up the m5 and 6 back home and putting them in my garden which is much larger then hers.
Thanka all again jake

ps Bathgate so sorry you lost your cat,must have been very distressing.