Oodles of Leaves Call UA Herbarium Home

TUSCALOOSA, Ala. – The University of Alabama campus is home to millions of leaves, perhaps most prominent in the new growth emerging each spring from the majestic oaks and on the azaleas preparing to dazzle.

But, there’s a few hundred thousand leaves on campus that are less apparent – meticulously preserved, neatly organized, and tucked away inside one of the buildings on campus. Some are more than 160 years old.

“We have one of the best plant collections in the state of Alabama,” said Dr. John Clark, curator of the UA Herbarium. Housed within the 4th floor of Mary Harmon Bryant Hall, the collection is home to some 70,000 dried plant specimens, which also includes non-vascular plants, which have no leaves, such as mosses, algae and fungi.

More than 90 percent of the collection are vascular plants and, typically, contain a branch with multiple leaves and either fruits or flowers.

“You can’t identify a plant accurately – unless it’s totally weird – without fruits or flowers,” said Clark, an assistant professor of biological sciences within UA’s College of Arts and Sciences.

And the identification of plants is a big part of the herbarium’s purpose.

“When someone wants to build a road or do any type of development, they need to know what is there,” Clark said. “The number one place they check is here. It’s not good enough to say, ‘well, this thing grows here because I saw it once.’ If you don’t have a specific specimen to reference, it doesn’t count. We need to at least have a reference from each major area of all the plant diversity.”

The preserved specimens are stored in five specially designed, movable cabinets, called compactors. These cabinets are 8 feet tall and 20 feet long with open shelving. Specimens are organized by plant families and bar coded, enabling researcher to quickly access computer data stored on each specimen.

More recent specimens are mounted on acid-free paper and labeled with GPS coordinates indicating the exact location where they were collected, the collection site’s elevation, along with the date and collectors’ name.

The herbarium’s primary focus is the flora of Alabama, Clark said. Secondary foci are plants of the Southeast and aquatic plants. It’s estimated that some 95 percent of the vascular plant species that occur naturally in the state are represented in the collection as are an estimated 99 percent of all the state’s naturally occurring moss species.

The 5,000-square-foot room which stores the specimens is typically maintained at 61 degrees Fahrenheit and 50 percent humidity to reduce the risk of an insect infestation. Before any specimen enters the collection, or if it’s being returned, it’s frozen for three days, at approximately -10 degrees Fahrenheit, to kill any pests which could damage, or destroy, the collection.

Regular visitors to the collection would include representatives of the U.S. Fish and Wildlife Service, major conservancies, and other research institutions. The herbarium has a strong teaching component, and UA students benefit from, and contribute to, the collection, Clark said.

Steve Ginzbarg, collections manager of the UA Herbarium, developed and oversees an online database linked to the collection. Data from the collection is accessible over the Internet to the Global Biodiversity Information Facility data portal, allowing botanists worldwide online access to the collection.

“One thing I’m really interested in doing is utilizing collections that are in the herbarium with molecular data to try and understand how plants are related to each other,” Clark said. “Whenever I’m in the field and collect something, I take a tissue sample.”

From those and other samples, UA students and researchers in the herbarium’s accompanying lab perform DNA extractions, and, subsequently, gene sequencing. Comparing and contrasting gene sequences of various species enables the researchers to build “evolutionary trees,” Clark says.

The point is to try and determine whether flowers, for an example, with similar morphology, or appearance, are related. “What you want to know is, is the similarity that you observe with your eyes – is that a result of recent common ancestry, or is it a result of independent origin?

“That’s one of the exciting things,” Clark says, while standing inside the sequencing lab. “I want to know, how many times did hummingbird pollination evolve, how many times did red flowers evolve, how many times did red flowers evolve from blue flowers. All these questions, we can address with an evolutionary hypothesis. And, we do that by a combination of collections-based and molecular-based techniques carried out in this building.”

While high-tech molecular studies and DNA sequencing have, in the last 15 years or so, revolutionized UA’s efforts to define phylogeny – the genetic relationships between organisms and how they are believed to have evolved through history – Clark says this doesn’t diminish the importance of the traditional collection.

“Without the collection in the other part of the building, these,” Clark says, motioning toward tissue samples, “would be worthless. They have to be referenced.”

The UA plant collection, developed in collaboration with UA’s Alabama Museum of Natural History, was built to archive, promote and distribute information on Alabama’s plant biodiversity.