The collection is growing and growing

4 March 2013

The herbarium at Johannes Gutenberg University Mainz (JGU) is hardly known – although it includes a number of rare plants and fungi, some of which are still awaiting proper classification. In addition to the extensive array of fungi and plants native to the Rhineland-Palatinate region and gathered from the Mainz Sand Dunes nature reserve, there are also exotic specimens from Costa Rica and Rwanda. Dr. Gudrun Kadereit shows what the herbarium has in store.

It just looks like a normal envelope, nothing special. Dr. Gudrun Kadereit carefully unfolds the piece of paper. What emerges is a piece of dried, pressed moss, a mass of tiny gray-brown stems and offshoots. The label identifies the plant as Brachythecium albicans and states that it was found in the "Mainz Sand Dunes Nature Reserve, at the edge of the copse". In 1978, Dr. Ulrich Hecker brought this moss from the nature reserve to the Herbarium Hortus Botanicus Universitatis Moguntinae, otherwise known as the herbarium of Johannes Gutenberg University Mainz.

"Ulrich Hecker founded the herbarium in 1964," Kadereit explains. For Hecker, at that time curator of the JGU Botanic Garden, it represented a new institution that would primarily serve as a comparative collection for the garden. Since then it has grown into much more.

New space for taller plants

The ceiling is quite low in the attic space of the Institute of Special Botany at Mainz University. Gray folders, so-called fascicles, are spread out on several tables that have been pushed together. Kadereit is pleased that it was possible to relocate most of the collection here in December 2012. The move was timed to take advantage of the relocation of the seed cleaning facility, now housed in a small new building on the Botanical Garden site. Kadereit, who in 2007 assumed responsibility for the university’s herbarium along with her research assignment, was quick to seize on the opportunity.

"This collection unfortunately lacks a full-time curator," she states. For years the herbarium has slumbered down in the basement. Now the botanist is drawing on support from the technical staff of the JGU Institute of Special Botany and several volunteers to tend to the roughly 45,000 specimens of plants and fungi from places like Colombia, Ecuador, Italy, and, of course, the Mainz Sand Dunes.

A water lily from Rwanda

New material is being incorporated all the time. "Last year that included 7,000 samples from the Gargano region of Italy alone." One of the institute's former research associates, Dr. Wolfgang Licht, spent a great deal of time with students in southern Italy – and whenever the institute undertakes a research project, whenever a doctoral candidate investigates plants or fungi, the herbarium is where the specimens end up. "It's not enough for us to just keep a photo here."

One focal point for the Mainz botanists is research into molecular-genetic relatedness. This field demands real specimens to provide precise clarification where the results are in doubt. Illustrations are simply not sufficient. The plants themselves have to be available, even if they are decades old.

Kadereit flips open one of the gray fascicles. "We give this one here extra special attention," she explains. Unlike most of the other folders, there is an additional layer of red pasteboard. Inside rests a water lily from Rwanda, Nymphaea thermarum. It came to Mainz University in 1987, which became the first institution in the world to identify it as a separate species. The plant is attached to a sheet of paper by means of narrow strips of cardboard. An offprint of the article by botanist Dr. Eberhard Fischer presenting the findings to the research community is also included.

This type of specimen is called a 'holotype' – the original type specimen – and there can only ever be one of these of this tiny water lily. It seems that the plant is now extinct in the wild, and even if other herbaria are continuing to cultivate Nymphaea thermarum, the species was first discovered by Fischer from Mainz, and so this is where the holotype is housed in its red envelope.

Switchover to the digital world

There are roughly 3,600 herbaria worldwide. The Mainz collection is rather small. In Berlin and London the number of specimens ranges into the millions. "Our collection is nice to work with because it's so manageable," Kadereit says.

The effect would be even more pronounced if the inventory for the collection was digitized. Kadereit and her helpers are working on precisely that. They have affiliated themselves with the database of the herbarium in Vienna in Austria, where the Mainz herbarium operates under the abbreviation MJG, short for Mainz Johannes Gutenberg. Some 10,000 specimens from the Mainz collection are already online, including a large collection of flora from Rhineland-Palatinate.

The greatest threat to the herbarium

Kadereit next heads from the attic down to the cellar. Not all of the Mainz collection has been relocated yet. The fungi for example are still in the basement. We pass a humming refrigerator. "The biggest threat to the herbarium is the herbarium beetle," she explains. These little insects love nothing more than eating the dried plants. To combat them, each fascicle is sent for a round of shock freezing at minus 25 degrees Celsius once per year.

Arriving in the cellar, the botanist points out a small plastic bucket. A few insects are swimming around in liquid collected in its bottom. "We do this to determine the extent of the infestation." Right now it is within the normal expected levels. But there have in fact been outbreaks that necessitated draining the oxygen out of the entire institute to rid it of the pests. "That's a very expensive procedure." And money is tight for the herbarium. "We're funded from the regular resources of the Institute of Special Botany."

The cabinets down in the basement are filled with stacks of bins containing dried mushrooms. Some of them are familiar looking, with the stereotypical mushroom cap. Others look like creatures from another world. "Few people realize that we have such an extensive collection of fungi from Rhineland-Palatinate," Kadereit says, before bending down to fish a couple of gray fascicles from a shelf.

Unidentified from Costa Rica

The files contain plant samples from Costa Rica, typical páramo or high mountain biome vegetation. These particular ones are Podostemaceae from the rivers and springs of Central America. "They look like algae, but they are in fact flowering plants." The label identifies the collector as Meinhard Grubert. His research trip was back in 1972. Yet the names of the individual plant species of many of the specimens are missing, indicating that more research is needed here.

In recent years there has been some movement in the JGU herbarium: the new space, the ongoing digitization of the collection ... "I wish I had more time for it," Kadereit claims. She is working on a herbarium website and there is already a new logo for the herbarium. And right now she and her helpers are collecting specimens from the Ober-Olm forest. "The area boasts a strong diversity of species, but hasn't been documented anywhere."

One thing is certain: the JGU herbarium will continue to grow with the help of Dr. Gudrun Kadereit and her assistants.