Botanical museum specimen

Preparation of museum specimens

Museum specimens of fresh materials

Dried plants specimens are preserved on a herbarium sheet and maintained in a herbarium according to their families. However, large and 3D materials (e.g. lichens, higher fungi, cones, fruits, cactus, etc.) cannot be pressed between the sheets of paper. Rather, they are preserved as such in the glass jar/box as museum specimen.

Dry and wet preservation of museum specimens

For preparation of museum specimen of fleshy materials like large algae, fruiting body of fungi, thalli of bryophytes, strobilus of pteridophytes, cactus, angiospermic fruits, diseased plant etc., whole plant or part thereof are well fixed in FAA (Formalin Aceto-Alcohol) and preserved in 70 % alcohol in an air tight specimen jar.

Recipe of FAA

Constituents	Quantity
Foramldehyde (formalin)	10 ml
Acetic acid	10 ml
Ethyl alcohol (70 %)	80 ml
Total	100 ml

The volume, concentration of all the three constituents and time for fixation should be adjusted according the nature of material to be fixed. Formaldehyde kill the cell. The volume of formaldehyde may be increased or decreased according the time taken for fixation. Acetic acid provides penetration power. The volume may be increased or decreased according to the volume and hardness of the specimen. For fixation of soft specimens few hours are enough, whereas, it requires 24 to 48 hours and even more for the fixation of large and hard material.
Likewise, concentration of alcohol may be decreased for the soft materials like algae and leafy bryophytes, or increased for the large and woody materials of gymnosperms and angiosperms.

Museum specimens of dried materials

For preparation of museum specimen of dry materials like, lichens, gymnospermous cones, etc., they are dried in microwave oven and kept in air tight glass jar. Spray of 2 % mercuric chloride (HgCl₂) on dried specimen before packing into jar protect the specimen from pests’ attack.