Recently I have had phone calls from Extension agents and Green Industry professionals in 3 states asking about “poisonous” hollies in the landscape. I am not sure what stimulated this sudden interest but will share what I learned. Please remember, I am neither a pharmacologist nor a toxicologist and I certainly have done no human feeding or dose response studies. That sort of work seems more appropriate for the medical community than for a horticulturist.
Plants That Poison by Schmutz and Hamilton states that the poisonous parts on hollies are the berries. “The berries of all species are reported to be poisonous if eaten in quantity. The toxic principle is ilicin. Although not considered very poisonous, the attractive red or black berries should be considered dangerous to small children [and animals].” Symptoms listed are “nausea, vomiting, diarrhea and stupor due to depression of the central nervous system.” They also note, “These are the hollies used extensively as Christmas decorations. Indians and early settlers used the leaves to make a mild brew such as ‘yaupon tea’.”
Common Poisonous Plants and Mushrooms of North America by Turner and Szczawinski, gave a more thorough treatment. In the section on English holly (Ilex aquifolium) and related species, they write “Berries and leaves may cause digestive upset; berries occasional cause of poisoning in children, but not known to be fatal.” They say the berries and leaves contain theobromine, a caffeine-like alkaloid listing the same toxicity symptoms as Shmutz and Hamilton. “However, fatalities from holly are unknown, and their poisonous properties are frequently overstated. Mild doses of the leaves or berries cause stimulation of the central nervous system, whereas higher doses cause depression of the central nervous system.” If large quantities of the berries have been ingested, they suggest that vomiting be induced followed by activated charcoal and a saline cathartic, excess stimulation caused by theobromine can be countered with barbiturates and benzodiazipines. Obviously, medical professionals need to be involved if treatment becomes necessary.
When I checked for specific toxicity references to our common landscape hollies, I found almost nothing. For the native evergreen species besides Yaupon holly, Ilex opaca, I. cassine, I. glabra and deciduous species, I. decidua and I. Verticillata, I found that the leaves of I. cassine were sometimes used by Native Americans like the leaves of I. vomitoria to make black drink. There were no other references uncovered that indicated these native species have any toxicity at all.
It seems that rather than panicking if holly berries or leaves are ingested, we should remember that Turner wrote, “Fatalities are unknown and their poisonous properties are frequently overstated.” In my search only a few species were listed as having medicinal uses. If your callers cannot watch what their toddlers [or animals] are eating, they probably have much more to fear from common beverages, condiments and household chemicals than from hollies in their landscape.
“POISONOUS” HOLLIES
by Richard E Bir
Taken from Auburn University Website