Efforts in recent years to digitize herbarium collections (i.e., image, capture label data, and georeference) have allowed for easier access to plant specimen data, facilitating study of the dynamic nature of our world's flora (Hedrick et al. 2020). In the United States, such studies are increasingly important in light of urbanization and associated habitat destruction, changes in land use, introduction of nonnative species, and climate change. Changes in the flora have economic as well as ecological effects, since habitat loss can affect water quality, wildlife populations, and other landscape attributes important in recreation and tourism (e.g., hiking, fishing). Documenting the flora provides an important tool for understanding historic trends, and those historic “snapshots” of the flora over time can be used in future projects such as habitat mitigation and species restoration. New, well-prepared herbarium specimens, along with thorough collection data, will be valuable additions in the future, providing modern records of distribution and phenology, as well as verifiable records of rare and nonnative species.
Traditionally, herbarium specimens have been used in systematics research as well as studies of floristic diversity and biogeography. Specimen data have also been used in making historical comparisons related to ecological succession and human effects such as habitat destruction and climate change (Lang et al. 2018). Assessing changes in phenology, diversity, and distribution over time, tracking introduced and invasive species, and monitoring the decline of rare or sensitive species are common themes in studies making use of herbarium specimens today (Dolan et al. 2011; Everill et al. 2014; Loarie et al. 2008; Primack and Miller-Rushing 2012; Willis et al. 2017). More recently, herbaria have been used to track correlations among taxonomic groups, such as pollinator networks (Mathiasson and Rehan 2020) and mycorrhizal associations (Heberling and Burke 2019). As well, floristics is increasingly being merged into species distribution modeling as a way to use data to identify potential habitat and predict future distributions (Loarie et al. 2008; Wershow and DeChaine 2018), and into spatial phylogenetics, an evolutionary approach to the assessment of biodiversity and endemism (Mishler et al. 2020; Thornhill et al. 2016). Digitization advancements have also paved the way for new initiatives such as the Extended Specimen Network (Lendemer et al. 2020). This concept recognizes that herbarium specimens may be analyzed in multiple ways, creating a suite of interconnected resources and information from a molecular level to the ecosphere. Thinking of herbaria in this way enhances the research potential of specimens and highlights the importance of new, quality collections.
Of course, these types of studies are subject to the inherent biases of plant collecting, but digitized collections allow for a better understanding of the geographic and temporal collection patterns of plant specimens. Daru et al. (2018) showed that there are strong biases for collecting certain taxonomic groups as well as for collecting in the spring and summer months, near roads, near herbaria, and in habitats of ecological interest. An understanding of historic trends in collection practices and of how specimens can be used for research and identification allows for more targeted efforts in the future such as collecting in underrepresented regions and habitats, and including less-familiar life stages in herbarium collections.
Even in well-collected floras, new records are not uncommon (Martine and Ward 2013). A scan through recent issues of Rhodora, for example, reveals many reports of species newly discovered in New England (e.g., Anderson and Moorehead 2020; Mickley and Taylor 2019; Nichols et al. 2020; Palermo and Curtin 2019). Other research journals from across the United States (Journal of the Torrey Botanical Society, Journal of the Botanical Research Institute of Texas, Madroño, and Aliso, among others) contain similar articles. The Rhodora examples represent, among other topics, range extensions from adjacent states and Canadian provinces, taxa that have escaped from cultivation or become established as a result of habitat mitigation projects, and previously unknown hybrids.
Even those with extensive knowledge of a region's flora will consult herbaria to confirm the identification of unusual specimens or difficult taxa. Because of this, the importance of good specimen preparation and data collection cannot be underestimated. For a variety of reasons, it is not uncommon to find misidentified specimens in herbaria (Goodwin et al. 2015). Incorrectly identified collections may be the result of a change in nomenclature following new research, a new introduction to the flora, cryptic or difficult-to-identify taxa, events such as hybridization, or the recognition of newly described taxa. Well-prepared specimens allow for confident confirmation or correction of specimen identifications. This is particularly important when documenting rare or nonnative species.
Regional consortia of herbaria in the United States share the goal of providing specimen data as a means of facilitating herbarium-based biodiversity research for the purposes of conservation, management, and education (for some examples see Consortium of California Herbaria 2020; Consortium of Northeastern Herbaria 2020; Southwest Environmental Information Network 2020; SouthEast Regional Network of Expertise and Collections 2020). These data portals give virtual access to participating herbaria, making it possible to view specimen images and their collection information. In addition to aiding basic research, virtual access can be helpful in identifying unknowns and correcting misidentifications. It also allows users to identify new introductions and gaps in species distributions.
One of the New England Botanical Club's strategic goals for 2020–2025 is to “serve as a significant force in efforts to document the changing flora of New England … and by spearheading the generation of new collections and botanical data to support researchers in their efforts to understand floristic changes transpiring in the current era” (goal #5; New England Botanical Club 2020). Unfortunately, recent trends indicate a decrease in plant collecting for systematic and floristic research (Prather et al. 2004a, 2004b). Students majoring in biology or ecology today have fewer chances to learn about the importance of herbaria and the voucher collections they house, in large part because botany programs and course offerings in United States colleges and universities are in decline (Cook et al. 2014; Gropp 2003; Hiller et al. 2017; National Academies of Sciences, Engineering, and Medicine 2020; Powers et al. 2014; Tewksbury et al. 2014). As a result, we find there are fewer opportunities for learning proper collecting techniques and best practices for specimen preparation and data recording. To fill that gap, we provide here some guidelines and suggestions that should result in high quality herbarium specimens, maximizing value for future study. We also include a checklist of reminders that can be taken into the field.
This paper is intended for an audience of inexperienced or less-experienced plant collectors who are likely to be working with a local flora. We expect those working on more specialized collections, such as for graduate thesis work in systematics or for a project outside of the United States, will work with a mentor or colleagues to learn techniques that work best for their particular plant family or country to be visited. This can be particularly important for permitting requirements, which we discuss briefly under Collecting Permits. Also, we recommend that anyone working in the field observe basic outdoor safety (at a minimum that includes carrying a first-aid kit, whistle, map and compass or tracking device, and water), dress for the weather, and be aware of local hazards (e.g., poisonous snakes).
The continued documentation of the flora, as well-prepared specimens with thorough collection data, deposited in an herbarium, will be an invaluable contribution to the future. Classes and workshops in floristics and plant systematics should include teaching about the importance of herbaria, as well providing experience in good specimen collecting techniques and data collection. Collecting in underrepresented regions and habitats, as well as including less-familiar life stages, is encouraged.
NOTES ON SPECIMEN PREPARATION AND DATA COLLECTION
Basic Supplies and Equipment
Plant press (with cardboard ventilators and blotters) and straps
Field press (or vasculum, or plastic bags)
Newspaper (trimmed to fit within press; important for later storage and mounting)
Trowel or digging tool, such as a hori hori knife
Clippers or knife for collecting branches
Pencil, pen, and/or marker for field notes (including notes on newspaper)
Field notebook or digital recorder for collection notes
Hand lens (10× is sufficient for most specimens)
Manila coin envelopes or folded paper packets (for seeds and any extra leaves)
Global positioning system (GPS) unit, maps, compass
Tape measure or small ruler
Camera
Field guide(s) or plant identification manual
Specialized Equipment
Tongs or gloves for plants with prickles, spines, or irritating hairs or oils
Waxed paper for aquatic species
Tissue paper for delicate flowers or dissected tubular flowers
Tray or plastic tub and turkey baster for finely dissected aquatic species
Hatchet or small saw if collecting bark
Foam sheets or extra padding if collecting specimens with bulky structures attached, such as acorns, nuts, or cones
Small vials or jars of isopropyl alcohol or fixative if collecting flowers or fruit that will be used for anatomical research
What to Collect and How Much
A good specimen should include adequate sampling of all the plant parts available, and if possible, all stages of development. Specimens should be representative of the population but should include the range of variation of the plants, not those that best fit the press. It is important to collect fertile specimens and, if possible, include both flowering and fruiting stages for angiosperms, which will aid in plant identification. However, it is frequently the case that only one of these stages is available at the time of collection. Refer to your field guide or manual to be sure you have the features and stages of maturity necessary for identification; many plants cannot be fully identified from vegetative specimens. When preparing to make a specimen, it is a good idea to first look around and become familiar with the habitat and the population. Quite often you will find plants in varying stages of development. Note that specimens with insect or fungal damage should not be avoided. Such damage could provide useful information and may aid in future research on pathogens or pests.
Sufficient material should be collected to reasonably fill an herbarium sheet (approximately 11 × 16 inches), leaving room for a label in the lower right-hand corner and a fragment packet. If possible, collect additional leaves, flowers, or seeds that could be used for research. Curators are increasingly receiving requests for destructive sampling (removal of leaf material for molecular phylogenetic analysis, pollen and seeds for scanning electron microscopy), which can affect the integrity of a specimen. Extra material placed in a fragment packet can be helpful to researchers, especially if the specimen has only a few leaves, flowers, or fruits.
Key Points to Consider When Making a Collection
For woody or large herbaceous specimens, the supporting branch should be cut (do not tear!) so that the attached petioles, axillary buds, and any stipules are retained. Always try to keep compound leaves intact.
For woody or large herbaceous specimens, the branching pattern should be evident in the collection if possible. Distinctive patterns or lack of branching should be described on the label.
A bark sample is often desirable when collecting woody plants. If that is not feasible, make sure to describe it on the label.
For herbaceous plants, it is important to collect roots and rhizomes. If thick or bulky, they can be cut longitudinally. Below-ground structures should be cleaned of soil (wash, shake, brush, or carefully remove as much as possible). Although cleaning roots and rhizomes removes a component of the rhizosphere (possibly limiting future study), doing so minimizes transport of soil pathogens and allows for the plant's belowground morphology to be seen.
Heterophylly (different shaped leaves) should be reflected in the specimen. This includes foliage that is different when juvenile or underwater, or on the upper vs. lower portions of a plant. Describe the kind of leaves collected on the specimen label. Check for juvenile plants in the area and collect multiple specimens if needed.
Monoecy or dioecy (flowers with only male or female parts) should be reflected in the specimen. Some species have both bisexual and unisexual flowers. Try to collect all flower types. If dioecious, collect male and female plants under separate collection numbers, or if plants are small, collect both sexes to include on one herbarium sheet.
Heterostyly (plants with long-styled and short-styled forms) should be reflected in the specimen. Collect each form under a separate collection number, or if plants are small, collect both forms to include on one herbarium sheet. Note that some species have three style lengths (e.g., Lythrum salicaria L.).
Take special care that each collection number consists of only one taxon.
Large plants may be trimmed to fill an herbarium sheet as long as the specimen reflects the whole plant. Alternatively, a large plant may fill up more than one sheet (using a single collection number). That information must be recorded on the specimen label (e.g., as sheet 1 of 2, sheet 2 of 2). Do not be tempted to collect the smallest plants or leaves just because they fit the sheet.
If plants are small, collect a sufficient amount of material to fill the sheet, leaving enough room for the specimen label, fragment packet, and herbarium stamp and barcode (see notes in What to Collect and How Much).
If plant populations are small (only a few individuals observed) or a species is known to be rare, conservation must be kept in mind. A photograph in place of collecting the specimen may be adequate for specimen collection. Refer to Bridson and Forman (1989) and Gómez-Bellver et al. (2019) for guidelines or contact the herbarium where your specimens will be deposited.
Arranging and Preparing Specimens for Pressing
For many plants, arrangement of specimens in a press is best done when the plants are a bit wilted. Some plants can be unruly and spring back into a three-dimensional configuration when first collected. On the other hand, some leaves can be difficult to separate or unfold once they have wilted too much. Unfortunately, that optimal timing varies from taxon to taxon and is learned only through trial and error.
It is important to learn a technique that works best for you and then get comfortable with it. The care given to a specimen in pressing will largely determine its future value. Poor pressing can be compensated for by careful preparation before mounting on an herbarium sheet, but only to a limited extent. Many collectors place their specimens into plastic bags initially and then transfer their specimens into a full press later. Others prefer a “field press,” stacking their plants in folds of newspaper with only an occasional separator, and without successive layers of blotters and ventilators, until they are moved into a full press. Modifications or adjustments can then be made upon transfer, when the plants are more amenable.
When pressing, the plants should be arranged so that the maximum information in the specimen is displayed. In well-pressed specimens, it will be obvious which side should be mounted up (except in the case of grasses and sedges). The following points should be considered when arranging the specimen for pressing:
Leaves should be spread to avoid as much overlap as possible. This will provide a good idea of shape, margins, and size, which may be important in identification.
At least one leaf should be turned to expose the lower surface, in case color, hairs, glands, or other characters limited to one side are needed for identification.
Fold and/or trim leaves to fit sheet.
For specimens with crowded leaves, some of the leaves can be removed, but petioles (or petioles and leaf bases) should be kept to show the position of the leaves on the stem.
Cut stems and small branches obliquely to show the internal structure. For some taxa, a hollow stem or features of the pith may be diagnostic. Cut, do not tear, stems or branches from the main plant.
Large leaves can be trimmed along one side of the midrib and folded or cut into sections.
Both aspects of the flowers should be displayed (adaxial and abaxial surfaces), and characters important for identification should be visible and/or recorded. Flower color may fade on drying. The orientation, size, or attachment of some parts may be difficult to discern after pressing. Consult with a manual while pressing to determine what features are needed for confident identification. A photo or collection in isopropyl alcohol can be helpful in these situations. Some collectors hold flowers in place with small wet scraps of newspaper.
Plants too large to fit the 11 × 16 inch fold of paper may be bent into a “V,” “N,” or “M” figure to fit the sheet. If a bent stem tends to spring apart, it may be restrained by inserting it into a slit in a separate piece of paper (Figure 1), and then the specimen pressed within the newspaper.
Specimens should not protrude from the fold of newspaper. Anything that is sticking out from the edges of the press will not be pressed flat and will not fit on the herbarium sheet. Those parts will have to be removed when specimens are mounted anyway.
If extra flowers are collected, they can be spread out and dried in folds of tissue paper. For tubular flowers, one or more corollas should be cut lengthwise and opened to reveal the inner part of the corolla tube.
Special Techniques
Some types of plants require extra care or special techniques when pressing, such as cacti, aquatics, and palms. We have given some basic descriptions here, but there are also instructions for preparing specific families or types of plants in the literature (e.g., see citations in Judd et al. 2016 or other plant systematics textbooks). The herbarium where your specimens will be deposited should be able to help with references and provide a tutorial. Remember that your technique will improve with experience.
Excessively bulky and fleshy stems and fruits could be pressed separately to get a well-pressed specimen. Most gymnosperm cones cannot be pressed flat without distorting their shape and so should be kept separate. They can be dried in small paper bags and should be labeled so that they can be reunited with the rest of the specimen during mounting or stored separately in the herbarium.
If pressing specimens with thick or lumpy parts, folds of newspaper (or foam) can be added for support or as padding to the thinner and more delicate structures of the specimen. This will aid in distributing the pressure when the plant is pressed. Otherwise, plant parts without pressing pressure may dry wrinkled.
Very large fruits or extras should be cut (some longitudinally and some transversely to show placentation) or sliced into sections and dried separately.
Succulent or fleshy plants should be cut longitudinally and/or transversely. In some cases, it may be necessary to scoop out inner tissue.
Floating or submerged aquatics can be successfully collected by “floating out” the specimens onto an herbarium sheet. To do this, submerge the herbarium paper under the specimen and slowly draw it out of the water. This can be done in the water body at or near the collection site, or in a water-filled tray or tub. A turkey baster works well for spreading out finely dissected leaves. Cover the herbarium sheet and its plant with a sheet of wax paper, and place that in a fold of newspaper. Because these specimens will be very wet, the newspaper, blotters, and ventilators should be exchanged for dry ones after 24 hours.
For cushion or tufted plants, it is often impossible to press the entire plant. Segments of a suitable size may be more appropriate to press, but care must be taken to not fragment the plant with disregard. Whole cushions can be dried in a padded press.
For very large leaves or stems, divide the plant material into separate sheets, and sequentially label all of the parts. Usually the base, middle, and apex are adequate. In these cases, it would be helpful to have measurements and/or sketches and photographs to accompany the specimen. For trees and trunks, a bark sample or photograph should be collected.
Many short-lived flowers are very delicate and will disintegrate unless collected early in the day and immediately pressed. The corollas of several types of flowers (e.g., Iris L., Calochortus Pursh) will stick to the pressing newspaper and easily become damaged. Detach some of the flowers; spread the corolla and press in a separate fold of wax paper, tissue, or non-absorbent tissue paper. Do not try to open the newspaper until the specimen is fully dried.
Bulbs or corms should be included with a specimen. Dig up underground parts carefully and remove soil. Small bulbs or corms can be cut in half lengthwise; larger ones should be sliced. Cut bulbs or corms can be pressed in a padded press to preserve their shape.
Conifer specimens often lose their needles as they dry. Some collectors freeze specimens or treat them with an ethanol solution. See Bridson and Forman (1989) or contact the herbarium where your specimens will be deposited for specific preparation techniques.
If possible, multiple heads should be collected of Asteraceae specimens. Different heads should be pressed so that both the involucre and flowers are visible, and another sliced longitudinally so that the receptacle and chaff can be seen.
Arranging the Press
Working flat on the ground or table, place each specimen in a single fold of newspaper. The newspaper should then be placed between two cardboard ventilators. One or more blotter sheets may also be included. Blotters are especially important for absorbing the extra moisture in aquatic or succulent specimens and for preventing delicate and/or fleshy leaves from bearing the imprint of the corrugated cardboard. The stack sequence within the press should be as follows: ventilator, blotter, specimen in a fold of newsprint, blotter, ventilator, etc. The wooden frame of the press itself is placed at the top and bottom of the stack, with two straps cinched around the stack near the narrow ends of the press.
As specimens are added to the press, every effort should be made to keep the press level for eventual even distribution of pressure. This will mean the use of alternate corners for roots or other bulky parts. Extra padding, such as thick folds of newsprint, is very useful when placed over or around bulky portions of specimens.
If possible, a full plant press should not be more than 18–20 inches thick (usually about 20–30 specimens). If additional presses are not available, then extra care must be taken to ensure that the press is cinched as tightly as possible. Ideally, one person should stand on the press, one foot on either side of a strap, while a second person cinches the strap as tightly as possible. The tighter the press, the better the specimen. Wrinkled specimens are likely to crumble over time. Once the press is as tight as possible, it can be oriented upright on its long side for drying.
Drying Field Collections
Once the press is closed and straps are tightened, the plants should be dried as quickly as possible. Faster drying means less difficulty with mold and loss of color. The press should be oriented upright on its longest edge such that any rising warm air flows through the corrugated ventilators separating the plants.
If you have access to a plant dryer, consider yourself lucky! If not, you can construct one using a box with an open top and an electric heater, preferably also with a fan. The press should be seated across the top edges of the box above the heating element. A collapsible drying frame (either a wooden box or metal frame with canvas skirt) may be used in the field and a camp stove or lantern used as a heat source. Detailed instructions for an inexpensive drier can be found in Blanco et al. (2006). A makeshift dryer can be a fire hazard, so should be monitored closely. Never attempt to dry specimens inside an oven! Easy and safe mechanisms for drying plants are car-top luggage carriers, paved walks or driveways, or an air vent or radiator in your home. Whatever your solution, keep in mind that the air should be flowing up through the ventilator corrugations, and plant should be dried as quickly as possible.
After plants have been in the press for 12–24 hours, the press should be opened for examination and any last arrangement of the specimens. For best results, especially with aquatic or succulent specimens, blotters should be changed at least three times during the first 48 hours. In many areas, blotters may be dried in the sun (usually one hour is sufficient). If specimens are to be dried without artificial heat, blotters should be changed daily until specimens are dry.
Recording Collection Data
Collection information should be recorded in three phases: (1) the date, location, collector's name, and collection number should be written on the newspaper while in the field; (2) the date, location (including GPS coordinates), collection number, tentative identification, and observations should be recorded in a notebook or other device while in the field; (3) more detailed information can be added later. As many details as possible should be added on the day of collection as time allows while the experience is still fresh, although complete identification and geography may not be added until later when more resources are available. Notes should be clear and legible, in the event that someone other than the collector transcribes them onto herbarium labels. It can be surprising how often the best of intentions (to complete identifications or create labels) go by the wayside, details disappear from memory, and collection notes become misplaced. Specimens without good label data are simply compost!
At a minimum, information for any specimen collected should include the following:
Collector's name and a collection number (some collectors use a lifetime sequential numbering system; others use sequential numbers with a prefix to indicate a year or project, such as 2021-1 or CW-1 for the first specimen of a College Woods project); the use of some sort of numbering system is encouraged
Date of collection (abbreviate or write out the month to avoid confusion between date recording conventions, and give the four-digit year)
Location (distinct from higher-level geography, such as College Woods or Mt. Major)
Geography, including municipality, county or equivalent, state or equivalent, and country
Habitat
Elevation
Description of plant(s), including color of flowers and/or fruits, height
More complete collection data should also include the following:
Locality: given as precisely as possible, such as distance from intersection or other landmarks, and including latitude and longitude coordinates or other grid references, such as Universal Transverse Mercator or GPS coordinate system and datum used
Detailed information about habitat and ecology, such as aspect, slope, soil characteristics, vegetation type, associations with other plants, exposure, relative abundance (how many, how common)
Habit: characteristics of the plant itself, such as growth form (e.g., tree, shrub, vine, herb), root type or other below-ground features (e.g., tap root, fibrous, tubers, corms), size measurements or estimates (e.g., height, diameter at breast height, diameter of cushion or mound-forming species), distinctive growth or branching patterns
Additional noteworthy characteristics of the plant, such as deciduous or evergreen; presence and color of latex; leaf texture or color; flower color and/or scent; fruit color, texture, odor; and any behavior (e.g., blooming in morning only or touch-sensitive leaves), or any feature that is not likely to be preserved well in a dried specimen
Local or common name and any uses if collecting with an ethnographic focus
Preparing a Specimen Label
A look through any herbarium will reveal a diversity of herbarium specimen labels and the information they include. Some older labels are quite brief, especially if they were for specimens that were part of a personal herbarium. Handwritten labels can be difficult to decipher. At a minimum, the label should include scientific name and author, collector's name and collection number, date, location, and full geography as described under Recording Collection Data. More detailed labels will provide the most value to researchers in the future, and so we provide categories for additional types of information, as well. Examples of good labels are given in Figures 2–3. Labels should be printed on acid-free rag paper and formatted with economy of size in mind (the herbarium sheet needs to accommodate the specimen, label, fragment packet, and herbarium barcode, without overlap).
Figure. 2–3.
Examples of specimen labels. 2. Label with minimum collection information, including collector name and collection number, collection date, location, geography, habitat, elevation, and description of the plant. 3. Label with more complete information including the minimum collection information and precise locality, detailed information about habitat and ecology, and characteristics of the plant.
Collecting Permits
A critical component to any anticipated fieldwork is obtaining the necessary permits or permissions required for the collection of specimens on public or private lands. State and national government agencies such as the National Forest Service, National Park Service, United States Fish and Wildlife Service, and the Bureau of Land Management have permit applications available on their websites. Permit applications usually require information such as primary collector and any associated collectors, purpose of the collection activity, location of the study site, methods of collection and data analysis, date range when fieldwork will be conducted, timeline of the work to be completed, herbaria where voucher specimens will be deposited, and submission date(s) for annual or final reports. Make sure that you are informed of any ongoing management practices, especially habitat mitigation, prescribed fires, and animal removal. Permits should be obtained well in advance of making the collections, as processing time may take up to several months. Any permits should always be carried while conducting fieldwork. For areas that do not require an official permit, contact the property owner for permission.
Permission to bring plant specimens into the United States from other countries should be obtained well in advance of any collecting trip. Import and phytosanitary permits may be required in addition to local and national permits, and some of these can take months for approval. The United States Department of Agriculture Animal and Plant Health Inspection Service (USDAAPHIS) website should be consulted, as well as botanists in the countries to be visited, to learn about applicable laws and permits.
Sensitive Species
Special concerns need to be considered regarding the collection of sensitive species (rare, threatened, endangered). Unless specific research is being conducted or a new occurrence is being documented, sensitive species should not be collected. State- and federally listed species cannot be collected without a permit. Before making any collections in an area, know which species are locally and nationally rare, and those that are likely to be found on the site. If collecting sensitive species, collect discriminately, even in large populations. Avoid collecting from small populations. Collect the minimum amount of material necessary for documentation. When feasible, use photography or other methods of documentation (field notes, drawings, GPS coordinates) rather than collecting. Collect only a single specimen when it is essential to verify a possible new record for an area or to obtain a scientific voucher. For voucher specimens, collect only a small part if that would be adequate for unambiguous identification. Collecting whole plants is discouraged when plant parts are sufficient. Do not collect samples in so large a quantity as to adversely affect the population's survival or reproductive output for the year, and never collect the only plant at a site. Minimize any negative or long-term effects on the site such as trampling or transporting potential competitors, predators, invasive species, genes from other populations, or transmitting diseases among plants. Determine the extent to which available collections will suit the needs of the research. Before collecting multiple specimens to send to herbaria, make sure there is a clear need at those institutions for the number of specimens you wish to collect. Be sure the plant is abundant enough to withstand the collection of multiple specimens. Take special care of the specimens that are collected and do not let any material go to waste. Provide full documentation of the species and the site and take time to make other relevant observations, such as pollinators, herbivores, nonnative or invasive species in the area, and any damage or disturbance to the site.
Specimens of sensitive species should be deposited in an appropriate, recognized, and publicly accessible herbarium within an appropriate timeframe after they have been collected. Include all collecting permit information on specimen labels. Additional information and resources regarding the collection of sensitive species can be found through the United States Forest Service (2020).
SUBMITTING YOUR SPECIMENS TO AN HERBARIUM
As explained earlier, herbarium specimens represent a valuable record of the flora in a specific place and time. If your specimens are not labeled and deposited in an herbarium, that important information is lost to future researchers. Well-prepared specimens will allow future researchers to determine if the specimens were properly identified, which can be especially important in cases of nonnative introductions, as-yet-unknown hybridization events, cryptic species, and the recognition of new taxa.
It is a good idea to check with the curator or collections manager before submitting specimens to maximize their value to the herbarium and to facilitate their inclusion into the collection. Most curators will want the specimens unmounted, with labels printed on acid-free rag paper. If mounted specimens are accepted, there may be specific instructions to follow, such as the type of paper used or preferred space left empty for a barcode and fragment packet. The curator may also want a Microsoft Excel, comma-separated value (.csv), or tab-delimited text file or similar spreadsheet with the label data (check ahead of submitting), which then can be quickly uploaded into an online portal or herbarium database. Some herbaria do not accept photos either as part of or in lieu of specimens, but if they are accessioned, there may be specific instructions for how to submit them (contact the herbarium ahead of time or see Gómez-Bellver et al. 2019 for guidelines). The curator will also want a copy of any permits that were necessary for collecting on state, national, or some private land. If the specimens were collected as part of a research project, the curator will also want literature references, GenBank numbers, and other associated documentation.
ACKNOWLEDGMENTS
We thank Alice and Melanie Schori for suggesting this topic. Thanks also to three anonymous reviewers whose comments and suggestions helped us improve the manuscript.
LITERATURE CITED
Appendices
CHECKLIST REMINDERS FOR FIELD COLLECTING
Collect
Choose specimens representative of the population.
Collect enough material to fill an herbarium sheet or note if a specimen will fill multiple sheets.
If only a few individuals are present or a species is known to be rare, consider a partial sample or a photograph unless you have a permit or a compelling reason to collect.
Make sure each collection number includes a single taxon.
Large or woody specimens should exhibit branching pattern and axillary buds.
For woody plants, include a bark sample, photo, or description.
Always try to keep compound leaves intact.
Heterophylly (different shaped leaves on one plant) should be included.
Include flowers and/or fruits, especially as necessary for identification.
Describe colors, shapes, and scent in field notes and take photos that will help with 3D features that may be obscured in pressing.
Collect all flower morphs. If flowers are unisexual, note monoecy or dioecy.
Press
12. Check manual to make sure all structures necessary for ID are collected and visible.
13. Press specimen so that both upper and lower leaf surfaces are visible.
14. Press specimen so that the shape, margins, and size of leaves are evident.
15. If the plant has tubular corollas, include one or more that have been cut lengthwise and spread open.
16. Press specimen so that adaxial and abaxial surfaces of the flowers are displayed, and characters important for identification are visible. Take photos if possible and consider whether collection in alcohol would be of value.
17. When pressing, make sure specimen does not protrude from the fold of newspaper. Tall plants may be bent into a “V,” “N,” or “M” figure.
18. Press bulky and fleshy stems and fruits separately and label so that they can be reunited with the rest of the specimen later. Consider if these should be cut to reduce bulk.
Record
19. Label the newsprint with minimal information that will connect to your detailed field notebook.
20. Record in notebook or digital recording device:
Collector's name and a collection number
Date of collection (month written out and 4-digit year)
Location (e.g., College Woods, Mt. Major)
Geography, including municipality, county, state, and country
Locality, including distance from intersections or landmarks, and latitude and longitude coordinates or other grid references, such as UTMs
Elevation
Information about habitat and ecology, such as aspect, slope, soil characteristics, vegetation type, associations with other plants, exposure, disturbance, relative abundance
Noteworthy characteristics of the plant itself, such as growth form, below-ground features, plant height, diameter at breast height, diameter of cushion or mound-forming species, leaf texture or color, flower and/or fruit color, distinctive textures or odors of flowers, fruits, or foliage
21. Consider photographs that may help with anything you forgot to record!
