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Lecture/Workshop: Protocols in the Preparation of Plants and Voucher ID

Introduction to Plant Studies

A plant obtained from the field or from other sources such as local herb market may trigger one’s

interest in the biological potential of the plant. Possibly some traditional knowledge on the plant such as its

ethno-botanical, ethno-pharmacological, ethno-pharmaceutical and /or ethno-medical information may

develop this interest.

While it is useful to know as much of the traditional knowledge about the plant, it is essential to first

determine the correct botanical identity and to keep a permanent documentation of the plant. Such

documentation is referred o as herbarium/voucher specimen. This specimen provides a helpful means for the

botanist to identify the plant.

1. Plant Samples needed for Botanical Identification

Plant samples used for obtaining the correct botanical identity as well as for the herbarium specimen

ideally include the vegetative and the reproductive parts of the plant, such as the roots, stems, leaves, flowers,

fruits, and seeds. For trees and shrubs, the flowering and fruiting branches are sufficient. Specimens are

essentially collected/ obtained in duplicates, at best in sets of four to five samples.

The plant samples can be sent to a local botanist or to the local herbarium for identification. If fresh

samples cannot be identified immediately, then the pressed dried specimen is needed.

What useful information should accompany this specimen? If the plant sample is to be used for

scientific study, it is best to record all relevant obtainable data from the field such as where, when and who

collected the plant. Other information available, such as the ethno-botanical, ethno-pharmaceutical, ethno-

pharmacological, and ethno-medical information on the plant should also be recorded including the sources of

this information.

If a number of plants have been collected, it is best to assign a field number/code for each plant

collected. This code is written on a tag tied securely around the stem of the specimen. Other useful

information on the code tag could include with the plant number, the initials of the collector, the location and

the date of collection.

All information on the plants collected and gathered in the field about the plants should be recorded

immediately in a field notebook. This includes the field number/code and all the relevant information tagged

on the plant.

Coding Plant Specimen

A field number/code may look like this: 023 ADC Plwn 12/07/01

for plant number 23, collected by Anna D. Cruz in Palawan on 12 July 2001.

Sample entry in the field notebook

Date: 12 July 2001

Collected in Coron, Palawan; specimen 023, a small shrub along the roadside

Locals use the fresh leaves as poultice for sores.

- Source of information: Mang A. Bala, long time resident of the place;

- Conducted by Anna. Cruz, Biology student Class ‘03

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2. Preparation for Field Collection

Botanical field trips are exciting experiences allowing one to be close to nature. One can get lost in his

thoughts standing in awe, admiring the beauty and wonders of nature. So it is important to keep one’s

focus on the objectives and expectations from the field trip.

2.1. Objectives and Expectation from the Trip

The objectives must be clear and specific at the start of the planning session.

2.2. Preparations needed for the Botanical Collection

Determine the place of collection, the contact person(s), if any, and the possible duration of

the collection;

Get a map of the location and secure local permits (IMPORTANT);

Study the weather bureau climate report for the duration of the projected trips;

List the plants/specimens to collect;

Prepare the field notes to record;

Pack the botanical equipment and supplies to bring along.

Determine the techniques/methods to use in the collection;

If working with a team, meet the team members and orient them with the plans on the field

trip;

Remind the team about the ethical standards to observe in the field collection.

2.3 Equipment and Supplies

2.3.1 Aids to the plant collection

Garden tools such as pruning scissors, scalpel, trowel, bolo, and dissecting needle

(figure B1).

B. Road maps and compass to guide the collectors.

2.3.2. Preparation for the herbarium specimen

Plant press, consisting of a pair of wood/bamboo or steel frames;

Corrugated boards, aluminium ventilators and blotters for driers;

Specimen tags of cardboard or cartolina, about an inch long, with short cotton strings to

attach to the specimen;

Transparent plastic bags, big enough to store the collected, unpressed plants, which

have been properly tagged and wrapped with moist newspaper.

Paper/ plastic bags/ jars to hold seeds, fruits, flowers, cones, bark pieces and other plant

materials which cannot be included with the pressed plant;

Jute/ rice stacks to contain all the plastic bag collections;

Waxed paper or cheese cloth to cover succulent plant parts to prevent them from

sticking to the newspaper.

Stacks of old newspaper to sandwich and to dry the collected specimen and to wrap

unmounted plant materials;

Forceps for picking up tiny specimen;

Dissecting needles to help arrange minute parts of the specimen when pressing;

Tissue paper or clean soft cloth to wipe off dirt or drew from the specimens to be

pressed;

Alcohol (70%) and formalin to preserve wet collected specimen;

Plastic tapes to seal containers.

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2.3.3. Aids in the documentation of the plants collected

A. Field notebook and field labels where the field numbers and all pertinent data on the plants

are recorded;

B. Pencil (Mongol #1) and indelible black pen;

C. Field lens

D. Camera to record data not evident in the specimen such as plant habitat, color of flowers

etc.

Plant press

The plant press may be made from two flat frames of wood or bamboo 14”x20”. Each frame is made up of

vertical strips of 5 wooden strips measuring 3/4” wide, 1/4'’ thick and 14” long. The 4 horizontal wooden strips

measure 3/4”wide, 1/4" wide and 20” long. The strips are equidistantly spaced and nailed as in a lattice as shown in

Figure b2a. These frames are fastened together by abaca twine or nylon cord.

A pair of rectangular metal frames with wire mesh of a similar size as above may also be used. See figure

B2b. End hooks are provided in the metal frames to fasten these together with short chains.

The simples and cheapest kind of press may be made from two sheets of 1/4” plywood. The frames are held

together by two belt straps with buckles as shown in figure B.2c

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3. The Field Collection

Ideally, to collect plant is sets of 4 to 5 samples; avoid indiscriminate collection and

depletion of plant specimen. Collect only HEALTHY plants or portions of plants.

- For herbs (non-woody plants), collect complete with roots, stems, leaves, flowers, fruits,

and seeds;

- For underground parts such as bulbs, tubers, rhizomes, and fleshy roots, excavate carefully

and remove dirt thoroughly;

- For large fruits, cut cross-sectional in about 1” thickness;

- For woody and bigger plants, include small branches or twigs with reproductive structures,

healthy leaves, stipules when present; and other features of the plant; also the bark and

wood samples;

- For inflorescences and infructescences borne on the trunk, carve out these parts from the

plant including a piece of the bark.

Immediately, tag all collected materials with their corresponding number/ codes and

record on the-spot all relevant data in the field labels and notebook.

Use dark lead pencil (Mongol #1) on all label and notations to ensure that the writings

are not washed out or smeared when plants are wet or when the specimen is treated

with alcohol or formalin;

Press all collected specimens as soon as possible.

If immediate pressing is not possible tie together with plastic twine, all collected plant

specimen with their tags and field labels and place in individual plastic bags for alcohol

treatment as soon as possible.

Important precautions

Collections from the same plant are given the same number. Specimen tags and field label should

accompany each specimen and entered in the field notebook. NEVER trust on your memory.

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4. Preliminary Preparations of the Plant Specimen in the Field

Plant specimens are best pressed in the field and preliminary drying done when time and

favourable conditions permit. If not, then pressed plant specimens are preserved in transparent plastic

bags.

4.1. Pressing the Plant Specimen

A. Wipe off any dirt and dew from the plant specimen. Use tissue paper or clean soft cloth;

B. Arrange the plant specimen including their tags, with all the parts collected, in between sheets

of old newspapers in their natural position as possible. Position some leaves face up and others

face down; thin off the overlapping leaves in the specimen;

C. Partially cut the petioles or leaf stalk to show their origin and leaf phyllotaxy, that is, the

arrangement of the leaves of the leaves in the stem.

D. Straighten or discard any crumpled, diseased or insect-bitten leaves;

E. Fit the plant specimen within the folds of the newspaper and the size of the plant press;

F. Place more newspaper, to serve as dryers, between the stack of newspaper holding the

specimen and blotters;

G. Press the whole bundle of sandwiched specimen and dryers between two plant presses and tie

the bundle tightly.

4.2. Drying the Pressed Plant Specimen in the Field

Dry the pressed specimens in the plant directly under the sun or near a bonfire to speed up

drying.

4.3. Preserving the Pressed Plant Specimen not dried in the Field

Place the pressed specimen in transparent plastic bags. Pour a solution of 70%

denatured alcohol through the sides of the pressed newspapers;

Make sure that all the specimens within the newspapers are liberally moistened with

alcohol.

Seal the plastic bag well with twine or plastic tape.

Important: Keep only one plant species between the folds of each newspaper sheet.

Treatment with 70% denatured alcohol

Treatment with alcohol causes fixation of tissues by arresting the activity of

abscissic acid thus preventing the leaves and other parts of the plant from falling off. This

treatment will preserve the specimens for three to four months.

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5. Final Preparation of the Herbarium/ Voucher Specimen in the Laboratory

Change the newspapers and blotter dryers in the pressed specimens; improve the arrangement

of the plants and its parts before pressing;

If plants are too large, bent the plants into a “V, N, M, W” shape; thick stems are slit to avoid

breaking;

Spread the flowers to show different views and arrange the leaves in such a way as to avoid

overlapping;

For bulky or fleshy stems and fruits, split the stems into two and include both parts in the press;

For large compound leaves, cut along the length of the leaf at the rachis, the structure to which

the leaflets are attached, and include only one half of the leaf in the press;

For very thick specimen, eliminate some of the water content by “salting out”;

Place small detached parts of the plant in paper packets and dry with the corresponding plant

specimen;

Arrange the specimen with their tags intact in newspaper folds, one after the other; separate

alternately by corrugated boards or ventilators on one side and blotters or newspapers on the

other side;

Place bundles of twenty to twenty-five plant specimens between two plant presses and tie

securely with nylon cord or abaca.

What is “Salting Out”?

“Salting out” is treating the thick parts of the plant with salt. After several hours, the

exuded water and excess salt are wiped off with tissue paper. Salt aids in the removal of

water and discourages the growth of fungi and molds.

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6. Final Preservation of the Plant Specimens

6.1. Drying

Plants may be dried by two ways:

a. Natural drying

Drying under the sun. Drying may take a few days or full a week or even more. Change

the dryers/blotters and newspaper in between specimen two or more times a day. Take

care to prevent loss of parts of the specimen during the changing process.

b. Artificial Drying

Drying with the use of heaters. Stoves and electric bulbs are placed in a cabinet dryer

holding the pressed plant specimen. This is a very convenient process.

Inspect the specimens every three or more hours to check the progress of drying

and to change wet/blotters and newspaper. Length of drying depends on the

moisture content of the material and the care in the drying process.

A Cabinet Dryer

A wooden cabinet with an open top may be prepared so that the plant presses are

filed in an upright position one after the other. The heaters, at moderate heat are placed

below. Avoid too high heat as this may “cook” the succulent specimens making the

materials black and brittle.

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6.2. Mounting

Mount the dried specimen in standard sized mounting sheets, 11 1/2 X 16 ½ inches, white

mounting sheets or thick cartolina of sufficient thickness.

Mount the specimen generally in an upright position at the same time allowing ample space

for the herbarium label.

Place inside suitable packets any detached plant part such as seeds, flowers, leaves tiny

fruits.

Paste the packet at a convenient place on the mounting sheets.

Methods of Mounting Specimens

There are four common ways of mounting specimens:

1. Adhesives. Specimens are glued with a colorless glue, such as Elmer’s glue. Weigh down the specimen until the glue

dries up. A cloth bag. Smaller than the mounting sheet containing very fine sand, will make an excellent weight since

all parts of the specimen will be equally weighed down.

2. Tapes. Strapping the specimen with filament tapes. These tapes come in different widths. The tape width will depend

on the thickness of the specimen. Care should be exercised so that important features of the specimen are not

covered by the tape.

Cellulose, scotch, adhesive or plastic tapes are never used. These tapes deteriorate with age becoming either soft or

brittle, discoloured or turn brown, leaving dark marks on the sheets, making the mounting unsightly.

3. Thread. Specimens may be sewn with heavy linen thread to the mounting sheet. A small hard board may be placed at

the back of the sheet where several loops are made on the stem or fruit. A knot is made on the reverse side of the

mounting sheet. This method serves to anchor bulky parts more secure than glue or filament tape.

4. Combination. A combination of the above three methods may be used depending upon the specimen.

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6.3. Labelling

Glue to the mounting sheets the labels of the corresponding specimen.

Place the field label, generally, on the upper left-hand corner and the smaller herbarium

label, on the lower right-hand corner of the sheet.

6.4. Labelling

Glue to the mounting sheets the labels of the corresponding specimen.

Place the field label, generally, on the upper left-hand corner and the smaller herbarium

label, on the lower right-hand corner of the sheet.

The Field Label

The field label contains the entire collector’s data done in the field.

The Herbarium Label

The herbarium label contains some collector’s data done in the field including the identification of the

specimen and verified by a taxonomist or specialist. The scientific name of the plants, its family and other pertinent

data are included in the label.

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6.5. Accessioning

The Accession Notebook is a record or directory of all the botanical specimens in the collections. The notebook is usually 1 or 2 inches thick, 8 ½” x 14” in size with numbered pages. Each specimen is given a definite accession number and numbering is made consecutively as plants are collected and filled.

Record in the notebook:

a. The herbarium number

b. The scientific name

c. The local name including the dialect name

d. The date of collection

e. The name of the collector and field number given by the collector;

f. The place where collected.

6.5 Filing

File flat the shelves of herbarium cases, the specimen properly identified and contained in

the species folders and genus covers,

Arrange the file in such a way that facility of locating specimen is a priority;

Use either of two methods of arrangement; the alphabetical arrangement or the phylogenetic

arrangement.

6.6 Storing Bulky Plant Materials

Succulent materials such as fruits and flowers may be preserved in jars immersed in a 5%

aqueous solution of formaldehyde with a 50-70% alcohol.

Not too fleshy plants, flowers, and fruits, cones and seeds can be dried by;

The improvised sand bath method then transferred to boxes for keeping.

Reference:

A Guidebook to Plant Screening: Phytochemical and Biological (Revised Edition).University of Santo Tomas.

2005.

Improvised Sand Bath Method

Use a box or can with a depth of 6-8 inches. Pour in a layer of previously washed and sterilized/roasted fine

sand. Arrange the specimen for drying on the surface of the sand. Pour more sterilized sand evenly over the

specimen. Wait for 15-20 days for the specimen to dry out thoroughly. This method preserves the color and

even the fragrance indefinitely.