BOTANY WITH THE BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

XIV. TOOLS AND METHODS FOR STUDYING AQUATIC VEGETATION

Specifics of preparing herbarium specimens of aquatic plants.

Collecting and properly drying plants during botanical research conducted in aquatic environments is a crucial part of the work. Often, insufficient attention is paid to it, resulting in specimens that look unattractive and cannot be identified.

The collection and drying of aquatic plants differ from terrestrial ones and have their own distinct features. Plants are dried in the same way as terrestrial ones, placed between sheets of newspaper in botanical presses. Herbarium preparation Methods are described in dedicated manuals [80, 107]. Useful advice on collecting and drying aquatic plants can be found in the book by V. M. Katanska [36].

To obtain optimal herbarium specimens of aquatic plants, the initial arrangement and drying in presses must be carried out meticulously. Whenever possible, the herbarium should include all PARTS OF THE plant: The ROOT System, stems and their modifications, leaves, inflorescences and flowers, as well as fruits and seeds.

Submerged plants and species with floating leaves that have thin rhizomes or lack roots are harvested using small aquatic rakes, dredges in deep waters, and bottom grab samplers from the bottom sediment. Plants are taken out with their root systems only from soft, muddy bottom deposits. Plants with thick rhizomes are cut using a sickle-shaped knife.

Afterwards, the plants are washed free of mud (in a bucket or from the side of a boat) and, before being placed in herbarium folders, they are either put into plastic bags (several bags of various sizes should be on hand) or wrapped in damp gauze pads (measuring 30 x 30 cm) and then placed in plastic bags. The bags containing the plants are tightly packed into a bag, where they remain until returning to the dormitory or home.

Placing most aquatic plants directly into an excursion folder, as is done with terrestrial plants, is undesirable; plants in such folders tend to dry out prematurely, causing their leaves and flowers to deform. Plants wrapped in gauze pads (especially species with dissected leaves) shed excess surface Water and can remain fresh for several days, decaying much more easily compared to those kept in plastic bags.

Plants with aerial stems and leaves that rise above the water, typically growing in shallow depths (such as arrowhead, bur-reed, flowering rush, etc.), are dug up using knives, spades, digging tools, or pulled out by hand. It is more difficult to excavate tall plants (reed, cattail, bulrush) that feature thick, resilient, and long rhizomes embedded deep in the substrate. Therefore, such plants are placed in herbarium folders without their subterranean parts, though strictly with Generative Organs included.

Broad-leaved pondweeds, hornworts, bladderworts, watermilfoils, and other plants with finely dissected or small divided leaves dry without major complications. If the specimens are dense and large, they are interleaved with layers of newspaper sheets. Damp newspaper must be replaced twice a day. To do this, a dry open folder is placed on top of the open folder containing the plant; then, holding both the top and bottom folders firmly with your palms, they are flipped over, and the wet folder is removed.

Plants with delicately dissected leaves (bladderwort, hornwort, watermilfoil) and other submerged species whose stems and leaves are covered with Algae must be transferred to fresh drying paper upon the first change of interleaves, while the plants are still damp, otherwise these plants will become permanently stuck to the paper. This process must be monitored closely and performed on time.

Particularly delicate and tender plants are first floated and spread out in a basin of water, after which a sheet of paper is slid underneath them. Carefully—so as not to wash the plant away—the paper is lifted out of the water together with the specimen, and they are dried directly on these sheets inside folders within a press using the standard method.

Large plants with thick, fleshy rhizomes and large, rigid leaves (sometimes exceeding the width of a herbarium sheet), such as water lilies, cannot be placed in the herbarium whole. Instead, several leaves with petioles, flowers, fruits, and the basal rosette of leaves along with a portion of the rhizome are taken. The rhizome and leaf rosette are cut lengthwise in half, unfolded, and placed into folders in this state. The fleshy interior is carved out of the rhizome. If the leaf rosette is very large, only one half of it is used.

Floating leaves, flowers, and rosettes with delicate submersed leaves are placed into separate paper sheets ("folders") accompanied by a label indicating the plant they belong to. Thick floating leaves usually become heavily deformed and lose their shape during the drying process. To maintain an accurate reference of the leaf's true shape and size, we recommend tracing its outline on white paper and inserting this outline into the folder alongside the leaf to be stored with the herbarium specimen. When pressing rosettes of tender submersed leaves, they should be interleaved with parchment or tracing paper; on top of the leaves, flush with the thick part of the rosette base and rhizome, a layer of folded paper sheets is applied and periodically replaced during drying. The interleaves placed between individual submersed leaves should not be removed until drying is complete; they do not need to be transferred to fresh paper. It is advisable to leave herbarium presses containing such plants under pressure for several hours to minimize the deformation of fleshy floating leaves.

A researcher collecting plants for a herbarium must be aware that many species of aquatic plants are listed in the Red Data Book of Ukraine and are legally protected. Before beginning fieldwork, one should review the lists of protected species in the regions where research is being conducted. For the Forest-Steppe zone and Ukraine as a whole, protected species are listed in this manual (see Chapter 9, Appendices A and B).