S. M. Tracy Herbarium solves problems in the plant world

Writer: Kay Ledbetter, 806-677-5608, [email protected]
Contact: Dale Kruse, 979-845-4328, [email protected]
Dr. Stephan Hatch, 979-845-4328, [email protected]

COLLEGE STATION – When researchers across Texas, and at times worldwide, hold up a plant and ask, “What is this?” they very well may be talking to Dale Kruse or Dr. Stephan Hatch at the S. M. Tracy Herbarium.

The looks of the non-descript metal building, hidden away east of the Texas A&M University campus at 3380 University Drive East, provides no indication of the importance of the work going on inside the Texas A&M AgriLife Research and Texas A&M facility.

“We get the hard-to–identify things,” said Kruse, curator since 1999. “These plants include potentially invasive species, plants toxic to wildlife and livestock, weedy species in pastures and gardens, and at times just pretty flowers found along the roadside.”

The S.M. Tracy Herbarium, a part of the department of ecosystem science and management, is a research plant collection with around 325,000 specimens housed in rows and rows of specially designed cabinets.

Some specimens housed in the herbarium date back to as early as 1819, nearly 200 years ago, said Hatch, who is the director and has been cataloging plants there for more than 40 years. The collections in the herbarium include specimens from vascular and nonvascular plants, lichens, algae and fungi. These plants are from every continent, including Antarctica, but the bulk of the collections are from the southern U.S., Mexico and the Caribbean.

The Tracy Herbarium was established in the 1930s and is based on several early collections, including that of agriculturalist Samuel Mills Tracy, who donated approximately 10,000 specimens to Texas A&M in 1917. Designated a National Resource Collection in 1974, the herbarium houses about 110,000 grass specimens – the largest grass collection in Texas and across much of the southern U.S.

Over the years, specimens have been added from various sources, Kruse said. Additions are obtained through annual collections by faculty, staff and students, who provide about 2,500-3,000 new specimens every year. In addition, an on-going exchange program with 30-35 other worldwide herbaria enhances the taxonomic and geographic scope of the collections.

Large numbers of specimens have been acquired through the incorporation of orphaned herbaria, he said. This would have resulted in the loss of many decades of work by researchers, and an immeasurable loss of research potential in the specimens themselves.

One such case is the recent incorporation of Texas A&M’s biology department herbarium in 2012, Kruse said. With the support of a $500,000 grant from the National Science Foundation, that herbarium was moved from the main campus and incorporated into the Tracy Herbarium, which now boasts as the third largest herbarium in Texas and 10th largest in the southern U.S., placing it in the top 5 percent of herbaria in the region.

“We interact with researchers across the country, across the world, as well as researchers here at the university in many diverse fields of study such as ecology, weed management, endangered species, and soil and crop sciences,” Kruse said. “We provide identifications for plants they are working with to more effectively and efficiently execute their research.”

Hatch said one such plant situation was the Cooperia pedunculata or rain lily. Dating back to the 1920s in Dewitt County, landowners had numerous, periodic poisoning problems. Livestock and deer that had white coloration or patches would develop festering sores and would temporarily go blind.

It wasn’t until the 1980s when work by Hatch and Dr. Barron Rector, a Texas A&M AgriLife Extension Service range specialist at College Station, narrowed down the cause. After extensive plant collections and observation, they initially determined the poisonings only happened immediately after rain events.

Hatch and Rector were in a rancher’s pasture following such an event and noticed a profusion of blooms from the rain lily. They collected the plants and conducted a number of toxicological tests on the specimens.

“We were really proud of ourselves that toxicology and biochemistry combined to solve the problem,” he said. “But in some further studies, there was no reaction to the plant, so we knew there was more to the problem.”

Hatch said he knew of some fungal associations causing poisoning problems involving Stipa robusta or sleepy grass, so they further studied the plant to determine if fungal hyphae were present.

With the aid of the Texas A&M Veterinary Toxicology Lab, they were able to piece together the puzzle and determined that fungal hyphae often invaded the plants and this combination of plant and fungus was the mechanism of poisoning.

“So now they know in a year when there’s lots of moisture and high numbers of rain lily, the producers can move their animals to pastures with very little or none and cut way down on the losses of weight gains and things that affect their profits,” he said.

Kruse and Hatch do a lot of identification of weeds or invasive plants people find in their pastures, crops, lawns and flowerbeds. The application of flowerbed mulch or use of hay from another part of the country can aid seeds from undesirable plants  or “weeds” to be transported to new locations and establish themselves.

“That’s when our job begins,” Kruse said. “Taking specimens often sent packaged between layers of newspaper or as images on the computer, we use various resources, including the existing herbarium specimens, to identify the plant and assist with determining its natural range and the potential as an invasive species.”

Such was the case of a relative to the fern-like plant, Salvinia minima or water spangle, which grows on the surface of water bodies throughout the southeastern U.S. and is fairly common in most lakes, Hatch said.

“One day I got a call from people in Houston and they said, ‘We’ve got a problem, we have a plant we can’t identify,’” he said.

Samples were sent to him and a researcher in Florida; both confirmed the plant was Salvinia molesta or giant water spangle, which grows six to 12 times larger than its smaller cousin, Hatch said.

“So the time this plant required to cover a lake to reduce oxygen availability to plants and animals that are below the water level was much, much faster,” he said. “We started by tracking down how it got out. It was brought in by people buying aquarium plants at a school and when they got rid of the aquarium, they put the plants in the schoolyard goldfish pond. And then somebody liked these water spangles and took some home.

“The next thing we knew, it was in some of our stock ponds. That’s when they got worried about it because of how fast it reproduced and took over the pond,” Hatch said. “So once we made the identification, they began trying to figure out a way to effectively remove large portions of it from the water, because it affects all the animal life, particularly fish.”

This type of identification, he said, is extremely important because invasive weeds can cause millions or billions of dollars in economic losses to state and local economies.

Once an invasive species is established in a new habitat, eradication can be extremely difficult, if not impossible, Hatch said. Often it is not an issue of eradication, but rather ongoing management of the populations, which is a recurring expense to the landowner or a governmental agency. In addition, losses to hunting, fishing and other recreational uses of the state’s natural resources are negatively impacted.