Stem: Smooth green near the top to usually a greenish-red near the base, the stem can be up to 15 inches high and the diameter of the plant can be as wide as the height. The stem is an above ground portion (a flowering scape) of the underground rhizome.
Leaves: In the true trilliums the leaf like parts are actually floral bracts just below the flower base. They are of course much larger than the normal small bracts that you see in other plants, but they are equipped to fulfill the function of a leaf. They are stalkless, with 3 to 5 prominent major veins and with a mottled green color, the mottling more pronounced when young, and resembling textured Hosta leaves. Bracts are three in number like all trilliums.
Flower: Yellow Trillium has a solitary pale yellow stalkless flower that has 3 erect yellow petals with greenish veins. These petals usually have a slight twist to them and initially conceal the stamens and the ovary. The six stamens are erect, the anthers are yellow, filaments greenish-white. The female ovary is pale green, composed of 3 united carpels causing it to be 6-angled. The style is very short, with 3 stigmas that are also erect, greenish-white and barely spreading. The 3 sepals, are light green with darker green veins and while initially erect around the petals, they spread downward toward the tops of the bracts when the flower opens. Flowers are about 2 inches high and are said to have a fragrant lemon aroma.
Fruit: Flowers mature to a greenish-white 3-celled 6-angled capsule, pulpy inside and containing numerous seeds. Read Eloise Butler's notes below in the bottom page section. Trilliums are tedious to start from seed as they must have a cold moist period, followed by a warm moist period, followed by another cold moist period, each period of at least 60 to 90 days. Planted in soil, they will thus germinate in the 2nd Spring. Then they will take 3 to 5 years before they flower.
Habitat: Yellow Trillium grows from thick rhizomes and will spread into a nice clump overtime if left undisturbed. Like most Trilliums it will grow best in well drained soil in light full shade or dappled sun under the tree canopy. The plant dies back to dormancy by mid summer.
Names: The genus name Trillium, is derived from the Latin trilix, meaning 'triple' and referring to the flowers having parts of three. The species name, luteum, means 'yellow' in Latin. The author names for the plant classification are: First to publish in 1813, but as a variety of Trillium sessile was ‘Muhl’ who was Gotthilf Heinrich Ernst Muhlenberg (1753-1815) American Botanist who produced several catalogues of plants after retiring as a Lutheran pastor. His work was amended in 1901 by ‘Harbison’ which refers to Thomas Grant Harbison (1863-1936) American botanist and horticulturist who was a collector for the Biltmore Herbarium, then with the Arnold Arboretum and finally with the University of North Carolina Herbarium. His six main publications concerned flora of the southern states.
The alternate common name of 'wake-robin' has been applied to many Trillium species, apparently because the Trilliums tend to bloom during the time that the robins are arriving in the northern latitudes. The name originated in the British Isles.
New Family: There is a movement among botanists to segregate the Trilliums and a few other genera out of the Liliaceae Family and into the Melanthiaceae. The U of M Herbarium has made this change on their Minnesota checklist but Flora of North America has not yet published this.
Comparison: Yellow Trillium, T. luteum, looks very similar to Sweet Betsy and Toadshade, T. cuneatum and T. sessile except that their petals are purplish. When grown close together, T. luteum is known to hybridize with T. cureatum and also with T. viride, the Green Trillium.
Above: The flower petals are a pale yellow with light green veining. Below them are the three sepals, a light green shade, with veining and the entire structure sits stalkless, atop the three large bracts, which resemble leaves, atop the smooth stem.
Below: As the petals spread apart, the yellow anthers of the stamens can be seen.
Notes: Yellow Trillium is not native to Minnesota but to a few states in the SE United States and Michigan and Ontario in Canada. This plant was listed on Martha Crone's 1951 inventory of plants in the Garden at that time, she had first planted it in Oct. 1946 with more added in 1949 and then again in 1955, '56, and '57. It was re-planted in 1993 and 1994 by Gardener Cary George and by Susan Wilkins in 2020. It is maintained as a historic Garden plant.
Eloise Butler Wrote: Trilliums are closely related to the lilies. All have a thick underground stem, bearing a single aerial stem, which supports a whorl of three large leaves varying somewhat in size and shape in different species. Above the leaf whorl arises the lovely flower, with or without a stalk; erect or drooping; white, red, purple or pink striped, according to the species. The flower is also on the plan of three green sepals, three colored petals, six stamens in two rows and one pistil made up of three united carpels. The name trillium probably comes from the three leaves. The plant has a number of local names - wake robin, bath flower and “way down east.” Published May 21, 1911, Minneapolis Sunday Tribune.
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"