Texas Trillium

	Texas Trillium blooms in March at Mercer's conservation nursery.

The article "American Treasures," featured in the spring 2002 Parkscape, discussed Mercer Arboretum & Botanic Gardens’ role in preserving threatened and endangered American plants in Texas. In 2001, the Center for Plant Conservation (CPC) assigned Mercer the maintenance of the Texas Trillium, another American treasure.

The name trillium indicates that the arrangement of the flower parts and leaves are in groups of threes. Trilliums, often known as trinity lilies, wake-robins, or wood lilies, are unique spring-blooming wildflowers. They form large localized colonies by means of their underground stems and by the germination of their seed. Trilliums grow only in North America and Asia. Outdoor enthusiasts consider these plants as sentinels of spring. Trilliums are often over-collected from the wild and Texas trillium is under threat from loss of habitat. 

Trilliums are considered part of the lily (Liliaceae) family, although, due to their unique characteristics some botanists propose to separate them into their own family. All trilliums bear a whorl of three leaf-like bracts below three colored petals. The petals of the Texas trillium begin as snow-white and then blush pink to magenta as they age. Each petal is 1.5 to 1.25 inches long. The flowers serve as signals to their pollinators and the odor of the flowers varies among the 50 or so species. Trilliums with sweet smelling flowers signal to butterflies, bees, and wasps, whereas species like stinking trillium (T. foetidissimum), the Latin word for fetid or foul, of Louisiana and Mississippi signal to their pollinators, the flies. Species including the stinking trillium that are pollinated by flies often have dull brown or maroon flowers and the smell mimics rotting flesh. 

Texas trillium stands up to 10 inches tall, bears mature leaves in whorls of threes, completes flowering in the spring, and rests during the hot months as underground stems. Shoots reappear from these perennial plants in late winter to early spring.

The Texas trillium is rare and found in the Piney Woods of East Texas as well as a portion of Louisiana. Texas trillium is found in shady, low, moist, wooded stream-banks, and sphagnum bogs (baygalls) often with sweetbay magnolia, red maple, black gum, wax myrtle, and Virginia sweetspire. 

Partners assisting Mercer for the maintenance of the Texas trillium for the CPC include Stephen F. Austin State University, the Texas Nature Conservancy, the Coastal Crossroads Chapter of the Texas Native Plant Society and Texas Parks & Wildlife (TPW). TPW botanist Jason Singhurst and associates completed a survey in Texas “The Genus Trillium” (Liliaceae family), for an issue of the botanical journal Castanea. Genetic studies by doctoral student Susan Farmer of the University of Tennessee will determine whether the Texas trillium is a unique species called Trillium texanum or whether it is a variety of the least trillium (T. pusillum) and thus named variety texanum. In addition, Cincinnati Zoo & Botanic Garden’s Center for Research of Endangered Wildlife (CREW) in Ohio has worked in partnership with Mercer for several years. CREW applies state-of-the-art technology to preserve the genetic diversity of rare exotic and native animals and plants. Dr. Valerie Pence heads the plant tissue culture and cryogenic (long-term freeze storage) laboratories.

Several of the rare plants maintained at Mercer including the Texas trillium are a challenge to propagate. All trilliums are notoriously difficult to germinate from dry seed. Reportedly, one batch of dry seed required over 20 years to germinate after planting! Fresh seed from trilliums usually require two spring seasons to germinate and require several years of growth prior to bloom. Because of this, Dr. Pence and her research group at CREW are developing methods to generate cultures of trilliums from sections of the underground stems to generate cultures from the embryos within fresh seed. Mercer has successfully coaxed Texas trilliums to bloom within the conservation section of the shade nursery (see photo), and is testing short-term storage techniques of the underground stems by extending their dormancy at refrigerated temperatures. Texas trilliums rescued from a construction site in Nacogdoches County will be cultured in custom-built propagation beds in Mercer’s conservation area. Future plans at Mercer include developing a public display in the Endangered Species Garden.

Over 500 species in the CPC’s National Collection of Endangered Plants, including those maintained by Mercer, may be viewed and studied online at www.mobot.org/CPC. Mercer’s Endangered Species Garden, founded in 1994 with support from Star Enterprises, displays a number of America’s native endangered plants on a seasonal basis.

Anita A. Tiller, Botanist
Mercer Arboretum & Botanic Gardens
Adapted from Parkscape, Summer 2002
Photo by Anita Tiller