I usually write a column when I get asked the same question many times. This month's question: "Is a Daylily a Lily?" gets asked often. And when I take non-daylily growers through my garden, that question is always asked. So this column is a combination of research done by two Ombudsman committee members, Eloise Koonce and Susan Bergeron, and  ex-Chair of the Scientific Committee, Pat Loveland.

QUESTION:

"I was on the wonderful AHS website when I read something that astounded me: Daylilies are not lilies. Are they in the lily family? I have an allergy to lilies so can I safely grow daylilies? This is very curious to me."

RESPONSE:

Eloise Koonce's research found that according to the AHS website, the daylily (genus Hemerocallis) is placed in the family Hemerocallidaceae and is not considered to belong in the lily (genus Lilium) family Liliaceae. In the fall 1987 Daylily Journal, Dr. Thomas C. Barr, Jr. wrote an article titled "Hemerocallis and the New Plant Biosystematics, Are Daylilies Cousins to Asparagus?" In the article, he explains the history of plant classification from its beginning in the second half of the 18^th century by the Swedish botanist Carl von Linné (Linnaeus) to the changes made in the present day.

To quote Dr. Barr, "Some of the more prominent differences between Hemerocallis and Lilium are the rounded or prismatic black coated seeds of the former versus the flat, stacked brown, thinly coated seeds of Lilium; the sepal nectaries (in the carpel walls of the flower base) versus the perigonal nectaries (at the base of the tepals); and the fleshy roots emanating from a crown in Hemerocallis versus the Lilium bulb composed of leaf scales." You may want to consult  Dr. Barr's article for more information.

In 1982 Hemerocallis was assigned its own family name by the plant taxonomists Rolf Dahlgren of Copenhagen, Denmark and Trevor Howard at the University of Queensland, Australia. Botanists and taxonomists are changing plant names all the time as they continue to learn more about plant relationships. So no, the daylily is not a lily.

Pat Loveland put this question to her scientific committee and this was their answer about how daylilies differ from lilies.

Daylilies have fleshy, tuberous roots and sword-like foliage which grows from a short crown just beneath the soil surface. The flowers are borne at the top of a leafless stalk called a scape, which also grows from the crown. See the diagram at http://www.daylilies.org/ahs_dictionary/ImageMap.html.

Lilies are comprised of a bulb which has fleshy scales growing from the top of a basal plate, and roots growing from the bottom of the basal plate. A shoot that grows from the top of the basal plate forms a single stalk, along whose length the foliage grows. The flowers are borne at the top of the stalk. Roots may also grow along the part of the stalk that is still underground.

Most of the daylilies that people grow today are hybrids developed over many years from the species daylilies, which are natives of Asia.

Now ... what about allergies? Daylilies and true lilies are not in the same botanical family, but that is not the crucial factor in allergic reactions. The question should be whether or not daylilies have the same compounds that cause an allergic response in lilies. If it is a chemical in the aroma of lilies that causes an allergic reaction, for instance, daylilies should be no problem. If it is a protein in lily pollen, this might or might not also be present in daylily pollen.

The following article describes the aromatic composition of the Oriental lily 'Siberia' and its effects on humans. Walking by Oriental lilies in a garden, one can tell that they differ in aroma: http://www.actahort.org/books/925/925_45.htm.

The chemical difference might be clearer using the example of an allergy to nuts. Some people are allergic to walnuts but not to almonds; some are allergic to both. These two nuts are from plants that are not closely related and their nutmeats differ greatly in chemical composition. However, like most plants, they have some chemicals in common; they have some similar proteins, for example.

Below are pictures that clearly illustrate the differences between a daylily and lily.

Daylily

Lily