Native Plant: Terrific Trilliums
Spring is a great time to head out for a wildflower walk. Hopefully you will get to see Ohio’s state wildflower, the large white trillium (Trillium grandiflorum). Trilliums are spring ephemeral flowers that are most noted for their symmetry Their bracts, petals, and sepals all come in sets of three. Even the seedpods are divided into three sections.
In early to mid Spring, they grow from a thick rhizome, which are fleshy, underground stems. Flowering mid Spring to early Summer. Then setting seed and dying back in mid-summer, they wait below the soil surface to emerge the following Spring.
All trillium species belong to the Liliaceae (lily) family and are rhizomatous herbs with unbranched stems. Morphologically, trillium plants produce no true leaves or stems above ground. The “stem” is just an extension of the horizontal rhizome and produces tiny, scale like leaves (cataphylls). The above-ground plant is technically a flowering scape, and the leaf-like structures are bracts subtending the flower. Despite their morphological origins, the bracts have external and internal structure like a leaf, function in photosynthesis, and most people refer to them as leaves.
Forty-three species of trillium are known worldwide with thirty-eight represented in North America. Within the United States, the bulk of Trillium diversity is found in the eastern states. Here in Ohio, we had 8 native species, though one was only recorded once in Northern Ohio.
Trilliums are broken into two groups, sessile or pedicellate. On sessile plants, the flower sits directly on top of its whorled bracts – look like leaves. On pedicellate, the flower is raised on a short stalk. Pedicellate trilliums can either have erect or nodding flowers. Sessile trilliums usually have mottled foliage, while pedicellate trilliums have showier flowers.
Some trillium species are endangered. If you wish to grow trilliums in your garden, always purchase from a reputable source that can guarantee the plants were not collected in the wild.
Even though it is a woodland species, the dormant plant needs to be warmed by the early spring sun. This need for early season sun is one of the reasons we are seeing fewer trilliums in the wild. Many of our natural areas are over taken by non-native invasive honeysuckle. Honeysuckle leafs out very early in the season, blocking the sunlight from the trilliums and other wildlflowers.
They need to be planted in soil that is rich in organic matter. They prefer deep, acid to neutral, moist, well drained soils. They don’t tolerate having wet feet, and so don’t thrive in heavy clay soils.
Trilliums are relatively easy to grow from their rhizomatous root but slow to develop and spread. To make up for it, the plants can live for up to 25 years.
Other than being browsed by deer, trilliums suffer from no serious pest or disease problems.
Various species of trillium are pollinated in different ways. Red Trillium (Trillium erectum) has no nectar and is pollinated by flies (Diptera) and beetles (Coleoptera). The petals of the flowers exude an odor that attract carion flies and beetles which pollinate the flower. Trillium grandiflorum is pollinated by Hymenoptera insects, including honey bees, bumblebees, and wasps.
Once pollinated, trilliums then produce small fruits, which ants take to their nest. They eat the fruit and put the seeds in their “garbage.” After germination, a root will emerge from the seed. The seedling develops in the dark, underground, for almost a year before sending a green leaf up to find the light.
Get Out and Enjoy Nature
If you don't get a chance to plant trilliums of your own, hopefully you will get a chance to get out in nature and spot a few. A few places where I have many trilliums, and many other wildflowers recently, are Miami University's Natural Areas and Rentschler Forest Metropark.
Blog: Guide to Trilliums of Ohio http://floraofohio.blogspot.com/2014/03/guide-to-trillium-of-ohio.html
Book: Wildflowers of Ohio by Robert Henn.
Native Plant List: https://www.ohionativeplantmonth.org/native-plant-list