The Missouri Botanical Garden recognizes that an integral part of herbarium management is the responsible stewardship of the specimens in its possession to insure their utility for future generations of researchers. Since the removal of material from specimens to extract DNA for molecular studies results in destructive sampling, Garden botanists have begun to regularly collect samples of material in silica gel specifically to support molecular phylogenetic studies. While the Missouri Botanical Garden encourages the use of its collections to further scientific research, it must ensure that its collections serve the needs of both contemporary and future researchers. It is hoped that this material, collected specifically for molecular analysis, will promote phylogenetic research while easing the demand on herbarium specimens.

Garden botanists have begun collecting small samples of plant material, usually young leaves, in plastic, zip-lock bags with silica gel as a dessicant. Voucher specimens for these samples are deposited at the Missouri Botanical Garden and at least one institution in the country from which they originated. Upon arrival at the Garden, a specimen label is prepared for each sample and they are stored in a cabinet in a walk-in freezer maintained at 0° F (-20° C).

Methods for Sampling and Drying Plant Material 

As methods for extraction, purification and amplification of DNA improve, we actually need very little plant material in order to adequately supply molecular labs. In general, we recommend collecting about 3-5 square inches of fresh, young plant material, normally 3-5 leaves or cut parts of larger leaves. If in doubt, err on the side of generosity. It is preferable to remove the midrib from leaf material before putting it into silica gel. Use scissors or secateurs to cut plant material. Tearing the material will bruise the leaves, releasing enzymes that will breakdown DNA. The most important protocol to follow when collecting material for DNA is getting the plant material to dry quickly and this is accomplished by increasing the surface area (cutting the leaves into smaller pieces) and using an excess of silica gel. The material is then placed in a resealable plastic bag with enough silica gel to ensure drying of the material in a couple of hours. Once the material is dry, most of the silica gel can be removed from the sample and dehydrated for future use. Indicator silica gel should be used to help determine the overall "dryness" of the sample. Check the sample for signs of mold and add fresh silica gel if necessary. Once dry the sample can be stored at room temperature without degradation of DNA, although it is preferable to store samples at -20° Celsius.

Goals of Collection

The material held in the Garden's DNA Bank has been collected to support studies of plant relationships. Thus the goal driving assembly of the collection has been maximum taxonomic diversity. The collection represents diverse geographic regions as well. In particular collectors have attempted to give special attention to seldom encountered and locally endemic taxa. This goal blends well with the goals of other Garden programs and is a service which is provided to support botanical research in general. Thus, the collection does not include the large numbers of samples from a single taxon that would be required to answer questions about the genetic structure of a single species or similar questions in population genetics.

The collections included in the DNA Bank have been made by Garden staff, but the Garden is willing to accept collections made by other individuals or institutions if they conform to certain standards. All collections must be accompanied by an appropriate voucher specimen deposited at the Missouri Botanical Garden. This will insure that identifications can be confirmed by all researchers using the DNA Bank. In addition, collections accepted by the DNA Bank must conform to the Garden's goals. Thus large numbers of samples of a single species, as are typical of population genetics studies, would not be appropriate and the Garden cannot accept curatorial responsibility for such assemblages.

Organization of Collection

The collection is organized in five major taxonomic groups: Bryophytes, Vascular Cryptogams, Gymnosperms, Monocotyledons, and Dicotyledons. Within each of these groups, collections are filed alphabetically by family and then by taxon.

DNA Bank Database

The collection of desiccated leaves available for DNA extraction at the Missouri Botanical Garden is a new project that is under development. The database that contains information for processed and curated samples has been dramatically changed. As you use this new information file and browse the database, please send comments and suggestions to Monica Carlsen:

The database is organized alphabetically by plant family, genus, and species and individual taxa can be selected to display information on samples in the collection. Information for each sample is directly linked to the TROPICOS record for the associated voucher specimen.

Available Taxa in the DNA Bank

Requisition Guidelines

Requests for material from the silica gel dried collection of samples should be addressed to the DNA Bank/Att: Monica Carlsen, 4344 Shaw Boulevard, St. Louis, MO 63110or can be sent by email to

Please include for each specimen requested the following data:

  1. Tropicos specimen ID number
  2. Collector and collection number
  3. Family and scientific name
  4. Country

Each request should outline the intended use of the material, including:

  1. a brief outline of the research proposed;
  2. a specific description of what material is required, in what form it is expected to be provided, and the anticipated length of its research use;
  3. the personnel who will be involved in the research and their credentials.

Requests for material must conform to all of the restrictions outlined below, including payment for samples or approval of an appropriate waiver request and a signed material transfer agreement.

The Missouri Botanical Garden maintains ownership of all plant material and releases samples only under specific conditions to support appropriate research projects. Samples in the Garden's DNA Bank have been collected solely for the purpose of supporting molecular phylogenetics and will be released only for the study of relationships of plants or for studies aimed at improving our understanding of evolutionary mechanisms. Samples will not be made available for bioprospecting endeavors, screening for genes of interest in agricultural research, or any other commercial application.

In order to defray a portion of the costs of maintaining, expanding and distributing the special collection, a contribution of $25.00 per sample supplied is requested. For students and those individuals without adequate funding, a request for a complete or partial waiver should be addressed to the DNA Bank/Att: Monica Carlsen, 4344 Shaw Boulevard, St. Louis, MO 63110.

As a condition of release for any samples specified on the attached list, each applicant agrees to abide by the restrictions stated above and also agrees to:

  1. all requests to pass either material provided by the Garden or extracted DNA to third parties must be approved, via a material transfer agreement, by the Curator of the Herbarium;
  2. acknowledge both the Missouri Botanical Garden and each individual collector of material provided in each publication in which data is used;
  3. provide the Garden with reprints from all resultant publications;
  4. publish jointly with Garden staff members or their foreign collaborators whenever appropriate;
  5. register GenBank/EMBL accession numbers.