Category: Toxic garden plant

This list spans several unrelated toxic mechanisms, and knowing which one applies changes how urgently to react. True lilies (and the related Lily of the valley, which works differently) are the single most urgent plant emergency for cats: even licking pollen off their fur or drinking vase water can cause acute kidney failure within days, with no reliably safe exposure threshold. Sago palms work on the liver instead, via a compound called cycasin, and are also considered among the most lethal common houseplants.

A separate group — oleander, foxglove, and (through a different route) lily of the valley — contain cardiac glycosides that disrupt heart rhythm. Azaleas and rhododendrons act on the heart too, via grayanotoxins. Daffodils, hyacinths, and tulips concentrate their toxins in the bulb, causing GI upset that gets more severe if a bulb is actually dug up and chewed rather than just the leaves. Holly, mistletoe, and poinsettias have a stronger reputation for danger than the evidence supports — they typically cause GI irritation and vomiting rather than the severe outcomes seen with lilies or sago palm. Chrysanthemums (pyrethrins), cyclamen (saponins, worse from the root), hellebores, ivy, and yew round out the list, with yew's taxine alkaloids capable of causing sudden cardiac events even in small amounts. The practical takeaway: if you keep any of these in a US garden and own a cat with outdoor access, identifying which one it is matters for how fast to act, not just whether to worry.

Toxic or dangerous (16)

Caution — unsafe in amount or frequency (1)