Recognized by all gardeners, Yellow Day Lily is a naturalized non-native introduced species that with it's lemon yellow color is a pretty sight against the background of green foliage on the central hill of the Upland Garden toward the end of June. Yellow Day Lily is an erect perennial growing from 2 to 4 feet tall. The flowering stem is a 'scape' (an aerial stem rising directly from the root), green, leafless and smooth.
The leaves are strap-like, long and linear with a keel, pointed tip, sheathed base and all basal. There are no leaves on the scape, but there may be several small leafy bracts.
The inflorescence is terminal cluster of long stalked flowers (a cyme) atop the scape. Branching occurs within the inflorescence and in the upper section of the scape. A plant may have from 8 to 12 flowers but only one open at a time.
The flowers are 6-parted, from 2 to 4 inches wide, very fragrant with a lemony scent and while diurnal, frequently stay open into the evening. Petals and sepals are combined into six yellow tepals; the outer 3 and inner 3 all have smooth edges (unlike the Orange Day Lily) and a parallel vein pattern. They unite at their bases to form a short tube. All spread and flare outward into a trumpet shape when the flower opens. There are 6 stamens with yellow filaments that curve upward from the base of the flower and are of slightly unequal length. The anthers are deeper yellow, turning darker as the pollen matures. The single style is yellowish with an indistinct 3-lobed stigma.
Seed: Fertile flowers form a 3-lobed cylindrical capsule containing shiny black rounded seeds about 3 to 5 mm in size.
Toxic: See notes below.
Habitat: Yellow Day Lily grows from an enlarged fibrous root system not from a bulb like the true lilies and tends not to spread. It is found along roadsides. woodland edges, and old gardens where it was probably planted as it is not invasive. It grows in a variety of soils but flowering will be much reduced if not in sun most of the day. Very dry conditions will shorten the flowering period.
Names: The genus Hemerocallis, is derived from two Greek words, hemeros, meaning 'day', and kallos, meaning 'beauty', referring the the beautiful flowers that only last one day. The species name, lilioasphodelus, is also from two words - Lilium for 'lily' and asphodel, referring its likeness to a lily-like plant whose roots were eaten (just like this plant). The author name for the plant classification from 1753, 'L.', refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. In older literature you will find the plant listed as H. flava.
Botanists have made an effort to separate the genus Hemerocallis from the Lily family and have created a new segregate family, Hemerocallidaceae, with 13–18 genera (2 in North America). Flora of North America (Ref. #W7 Vol.26) has referenced this and the University of Minnesota Herbarium has listed it on their Checklist of the Vascular Flora of Minnesota. Many references may not yet note this.
Comparisons: A companion in appearance to H. lilioasphodelus, is the Orange Day Lily, H. fulva. These two differ in that H. fulva does not have fragrant flowers, the venation of the tepals is reticulated, the tepals are orange, there are wavy margins on inner tepals and the species normally does not form seed. Gardeners know many of the clones of these species, currently over 38,000 named cultivars from the Hemerocallis genus.
Above & below: The six tepals are all the same color and have parallel veining. Each scape can have from 8 to 12 flowers - each only open for one day.
Below: A group of Yellow Day Lily in the Upland Garden.
Notes: Yellow Day Lily first came into the Garden on May 17, 1949, planted by Martha Crone, just 4 years after the Upland Garden land was added to the Wildflower Garden. She added more in 1950 and '51 and listed it on her 1951 Garden Census. Since it is primarily an introduced garden ornamental the MN DNR does not report county populations. The species was long ago introduced to Europe from Asia and then it made its way to North America.
Toxicity: The flowers, flower buds and enlarged roots are considered edible if properly prepared. The enlarged roots must be properly cooked as they contain the neurotoxin Hemerocallin. However, the shoots, leaves, stalks, should be avoided as the chemicals therein can be hallucinogenic. If you are allowing these to grow or purposely growing them in your garden be advised that the white tailed deer like the flower buds very much. Otherwise they (and rabbits) do not bother the plants. A liquid deer repellent usually works.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"