MBS Program Information

MBS survey procedures



Procedures - Rare plant surveys

The Minnesota Biological Survey (MBS) conducts rare plant surveys primarily for vascular plants and has provided funding for limited moss and liverwort surveys.

MBS botanist Karen Myhre searches for aquatic rare plants

MBS botanist Karen Myhre searches for aquatic rare plants. Photo by Carmen Converse

MBS plant surveys are conducted to:

1. Review of existing information

Prior to conducting field surveys for rare plants in a particular county or region, information is reviewed about the landscape and the plants that may be present. Some of the sources consulted are:

2. Selection of targeted plants and survey sites

Based on review of existing information, the rare plants likely to be present in the county or ecological unit are identified.

Sites and other habitats likely to contain areas of preferred habitat for the targeted plants are identified and a seasonal work plan is developed to optimize locating the targeted plants.

3. Field survey techniques

Botanists conduct field surveys for targeted plants mostly between late April and mid-September. Timing of searches for specific rare plants is determined primarily by the life history of the species (when does it flower or fruit?), with attention paid to variations in seasonal weather patterns.

Plant collections are made using standard herbarium procedures. A complete collection typically includes either flowers or fruit and underground portions of the plant. Certain groups of plants have more specific collection guidelines (such as sedges and woody plants). When a rare plant population appears to be secure, a collection is made of all or part of the plant. For conservation purposes, the roots of rare species are often not collected and only the portion of the plant required to make positive identification is collected. Occasionally only a photographic record is made of a rare species if it is adequate for positive identification.

MBS botanist Karen Myhre searches for aquatic rare plants

MBS Botanist Karen Myhre presses plant specimens in the field.

The freshly collected specimen is placed within a sheet of folded newspaper with the leaves, flowers, etc, arranged in a natural position but clearly showing the diagnostic features. The sheet is placed between blotters and ventilators, then put in a press and compressed by tightening straps around the press. The press typically accommodates many plants. It is placed in a warm and dry environment soon after collections are pressed to ensure proper drying and preservation. After several days of drying, the plants are removed from the press and stored in a dry place until identification can be verified.

4. Information management

Data collected during plant surveys are recorded on field forms, in electronic data files, and as museum voucher specimens. After field surveys are completed:


a pressed herbarium specimen

Herbarium specimen of water-hyssop (Bacopa rotundifolia), a species of special concern in Minnesota.