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

II. LIFE FORMS OF AQUATIC MACROPHYTES AND THEIR CLASSIFICATION

Environmental factors significantly influence the MORPHOLOGICAL Structure OF aquatic plants, as well as the patterns of their seasonal and age-stage development.

Investigating these features is essential for the phytodiagnosis of processes occurring in waterlogged substrates under METABOLISM/18.html">The Influence of natural and anthropogenic factors. Studying the life forms of aquatic macrophytes and their adaptive modifications is of profound importance. A significant number of studies have been devoted to the life forms and developmental forms of aquatic and wetland plants [134, 137, 140]

The Classification of aquatic macrophyte life forms is based on The Diversity of Organs that have evolved under environmental pressures.

This manual examines the classification of life forms of aquatic and wetland macrophytes in temperate latitudes, as proposed by D.V. Dubyna (1993).

When developing classifications for biomorph groups of aquatic and wetland plants, it is necessary to take into account habitat conditions, the morphological features of aquatic and wetland plants, and the ecological-biological and eco-Morphological Characteristics of species during ontogenetic development within lake and river systems of large complexes with minor or major Water fluctuations in natural temperate water bodies, as well as in water bodies with artificially regulated water levels (ponds).

Considering the Functions of ecophases, ecoperiods, and ecocycles in The Development of aquatic and wetland plants, along with Ellenberg's methodological approaches [122], aquatic macrophyte biomorph groups are categorized into the following types:

Hydromorphic

Euhidatophytes

Aerohidatophytes

Pleustophytes

Hydrogelomorphs

Teaganophytes

Pleustogelophytes

Hydroochtophytes

Ochtohydrophytes

Gelomorphic

Evochtophytes

Uliginosophytes

Hygromorphic

Trichohygrophytes

Hygromezomorphic

Pelohtophytes

Pelohtoterophytes

Euhydatophytes. These plants complete their entire life cycle in an aquatic environment encompassing the limnophase and coastal ecophase. Only their Generative organs may rise above the water surface for a brief period during flowering and pollination. They are capable of active metabolism directly with the water medium. Roots and rhizomes are typically embedded in the submersed layer up to 20 cm deep. In the mire ecophase, terrestrial forms are not developed. They exhibit a high reproductive capacity. This biomorph group plays a vital role in forming the primary organic mass of quagmires and floating mats in ponds and lakes.

Euhydatophytes act as dominant species (edifiers) within associations of the alliances Potamion lucentis (excluding Myriophyllo-Potametum) and Potamion pusilli. They less frequently form synusiae in other plant communities.

Representatives include genera such as Najas, Zannichellia, Ruppia, Zostera, alongside Potamogeton pectinatus, P. lucens, and P. perfoliatus.

Aerohydatophytes (hydatoaerophytes). Their life cycle unfolds across the limnophase and coastal ecophase. When the mimetic ecophase sets in, terrestrial forms develop that can sustain vegetation throughout the transitional period. Generative reproduction often culminates in the mire ecophase. Generative organs are positioned 5–10 cm above the water surface, though in certain species, they exceed 20 cm (e.g., Nymphaea alba, Nelumbo). They propagate both vegetatively (via rhizomes) and by seeds (hydrochory), with Vegetative Reproduction typically prevailing. Aerohydatophytes stand out in plant stands by their distinct habit and frequently produce terrestrial forms. Their rhizomes are robust and extensively branched. The ROOT System penetrates deeply into the substrate, while a substantial phytomass on and partially above the water surface enables aerohydatophytes to thrive even within the erosion zone. The Water Chestnut (Trapa natans s.l.), owing to its annual life cycle, is classified among hydrotherophytes.

Community functions: aerohydatophytes function as edifiers, dominants, or co-dominants in communities of the alliance Nymphaeion albae. They may also occur in synusiae along the margins of reed beds, as well as within communities belonging to the alliances Batrachion aquatilis and Batrachion fluitantis.

Representatives: Nymphaea, Nymphoides, Polygonum amphibium, Potamogeton natans, P. gramineus, and others.

Pleustophytes. Their life cycle is tied to the limnophase, coastal ecophase, and mire ecophase. During the terrestrial ecophase, individual plants die off. The root system of these surface-dwelling aquatic plants is either underdeveloped or weakly developed, absorbing mineral nutrients directly from the water Column. They drift across the water surface driven by wind and wave action. Their capacity for vegetative reproduction (via clone fragmentation) is remarkably high.

Optimal developmental conditions are found within the accumulation zone of water bodies. Both topical (statistical) and dynamic forms are distinguished [135]. Topical forms include pelagic, sublittoral, euhalitorial (eulittoral), terrestrial, and backwater forms; dynamic forms include diffuse (plants spread in scattered colonies across the entire water body), explosive (rapidly proliferating upon the onset of favorable conditions to form continuous mats on the water surface), and pulsating (plants colonize areas under favorable conditions and vanish during unfavorable ones, such as cold snaps and strong winds).

Community functions: characteristic species of the alliances Lemnion minoris, Utricularia vulgaris, and Hydrocharition morsus-ranae; they act as edifiers and dominants in independent associations and synusiae of other coenotic ranks.

Representatives: genera such as Salvinia and Azolla, along with Lemna minor and Spirodela polyrrhiza.

Theganophytes. The greater part of their life cycle, including generative reproduction, takes place within the coastal and mire ecophases. Generative reproduction is less prevalent than vegetative. Although plants spend a relatively brief time in the limnophase and terrestrial ecophase, significant morphological changes occur during these intervals. In the limnophase, plant size increases; driven by hydrostatic pressure and a weakly anchored root system, individuals detach and become temporarily free-floating. They can continue to vegetate for extended periods provided they anchor themselves within coastal floating mats (e.g., Eleocharis acicularis).

Pleistogeophytes. Most of their life cycle unfolds within the mire and coastal ecophases. In the terrestrial ecophase, they are capable of active vegetation for only a short duration.

These are medium-sized perennials featuring a robust fibrous root system and plagiotropic rhizomes. Their stems and leaves contain air cavities that provide buoyancy and structural stability in water over unanchored bottom sediments. Throughout the greater part of the growing season, the root system resides within the superficial layers of bottom sediments or suspended in the water column. Occasionally, plants detach from the substrate and drift as pleustophytes. Most species reproduce vegetatively via shoots, whereas Carex pseudocyperus and Cicuta virosa produce abundant seeds.

Community functions: species associated with plant communities of the alliances Cicution virosae and Alnion glutinosae.

Representatives: Cicuta virosa, Calla palustris, Menyanthes trifoliata, and Carex pseudocyperus.

Hydroochthophytes. Species capable of growing in the mire and terrestrial ecophases during their first year of vegetation, and in the land-coastal ecophase with full generative reproduction during the second. By the third year, they can inhabit the littoral-mire ecoperiod, which concludes with the gradual senescence and dieback of vegetative organs. The presence of this species group serves as an indicator of a critical ecoperiod and alternating ecocycles.

Species in this group are morphologically less vulnerable than the preceding ones. Their root system is weakly developed, reaching depths of 25–30 cm. Most of these species are biennial or triennial. Their life cycle typically initiates during the coastal-terrestrial period. Generative reproduction predominates (e.g., species of the genus Alisma, Oenanthe aquatica, Glyceria fluitans), though vegetative propagation is also quite frequent (e.g., Scirpus radicans, Bolboschoenus maritimus). Hydroochthophytes contribute to the accumulation process by participating in The formation of bottom sediments.

Community functions: these species form plant communities belonging to the alliances Oenanthion aquaticae and Sparganio-Glycerion fluitantis.

Representatives: Oenanthe aquatica, Scirpus radicans, Bolboschoenus maritimus, and Glyceria fluitans.

Ochthohydrophytes. For the vast majority of the growing season, these species are associated with the coastal, mire, and terrestrial ecophases, and spend only a brief time in the limnophase. They possess an extended life cycle.

This is a large group primarily originating from reed communities, characterized by large, robust above-ground organs and a well-developed root system. They stand out from other groups due to their size and physiognomy. With their deep-seated root systems, this group of species performs a bank-strengthening function and AIDS in the overgrowth and shallowing of water bodies as water levels drop. Their ecological role remains consistent across both accumulation and erosion zones. Reproduction is primarily vegetative and only occasionally generative (via anemochory or hydrochory).

Community functions: the physiognomic habit of these species dictates their littoral positioning as edifiers of communities belonging to the alliances Phragmition communis, Sparganio-Glycerion fluitantis, and partly Phalaridion arundinaceae.

Representatives: Typha angustifolia, Typha latifolia, Phragmites australis, Scirpus lacustris, Acorus calamus, and others.

Evochthophytes. Their life cycle is linked to the coastal and mire ecophases, during which the full development of rhizomatous shoots takes place. The hydrophase and terrestrial ecophase comprise only a brief window within the annual developmental cycle. Representatives of this group include large coastal sedges—both caespitose and rhizomatous—equipped with a well-developed, deep-seated root system. They occupy habitats in the coastal zone immediately succeeding reed communities (e.g., euhalitorial or eulittoral positioning). They exhibit a high capacity for both generative and vegetative (rhizome sprouts) reproduction.

Community functions: edifiers and dominants within littoral plant communities of the alliances Salicion albae and Alnion glutinosae.

Representatives: slender tufted sedge (Carex acuta), bladder sedge (C. vesicaria), greater pond sedge (C. riparia), etc.

Uliginosophytes. Species briefly associated with the littoral ecophase and for a prolonged period with the wetland and terrestrial ones. Plants of wetland habitats—medium-height herbaceous species with a branching root system. Perennials predominate. They are important Components of the accumulation process, yet do not play a leading role in sediment formation. A significant part of their life cycle takes place in the littoral, wetland, and terrestrial ecophases. Uliginosophyte species act as fillers in plant communities and determine their species richness. They feature diverse vegetative organs, with vegetative reproduction prevailing.

Role in communities: typically found as companion species in communities ranging from reed beds to floodplain forests and alder swamps; they exhibit a wide ecological amplitude across the classes Phragmiti-Magnocaricetea, Scheuchzerio-Caricetea fuscae, Salicetea purpurea, Alnetea glutinosae, and the order Agrostietalia stoloniferae.

Representatives: marsh spurge (Euphorbia palustris), greater water-parsnip (Sium latifolium), yellow loosestrife (Lysimachia vulgaris), purple loosestrife (Lythrum salicaria).

Trichohygrophytes. The greater part of the growing season is spent in the wetland and terrestrial ecophases. Following the desiccation of the topsoil layer, intensive root system development occurs and stolons are formed. Capable of developing under conditions of short-term flooding and complete ecotope drying. These are small perennial species, mostly with stolon-like shoots and a branching root system. They feature high reproductive capacity driven by SHOOT growth, whereas seed production capability is weak.

Role in communities: dominants and edifiers primarily of the alliance Agropyro-Rumicion crispi.

Representatives: silverweed (Potentilla anserina), creeping buttercup (Ranunculus repens), giant bentgrass (Agrostis gigantea).

Pelohtophytes. They grow in the wetland ecophase, where they complete their full developmental cycle. In the terrestrial ecophase, they typically develop in areas with exposed soils associated with a drop in the groundwater table. During the hydrophase, plants remain in a state of dormancy (as seeds). They tolerate the littoral ecophase for a short time. The full development of these species is linked to the critical ecoperiod characterized by the transition from the littoral to the terrestrial ecophase. After seed germination on unvegetated soils, they serve as indicators of the accumulation zone and as co-dominants or synusiae within plant communities. Their development is brief, usually lasting 3–4 months from late spring to late summer. In terms of development, they resemble therophytes. Generative reproduction predominates, and seed productivity is high.

Role in communities: species act as dominants and co-dominants in communities of the classes Isoeto-Nanojuncetea and Crypsietea aculeatae.

Representatives: least spikerush (Eleocharis ovata), Bohemian sedge (Carex bohemica), Coleanthus subtilis.

Pelohtotherophytes. Their life cycle takes place mainly in the wetland and terrestrial ecophases, with the bulk of the development period falling within the terrestrial ecophase. This is due to the root system being located at a considerable depth (30–40 cm or more). They can grow for some time under littoral ecophase conditions, which distinguishes them from pelohtophytes. These species are large (50–100 cm) and produce a significant number of flowers and seeds. In terms of their exo-aerenchyma structure and the presence of a robust adventitious root system, they resemble uliginosophytes.

Role in communities: act as dominants or co-dominants in communities of the Class Bidentea tripartitae, which includes many synanthropes found in communities of the class Oryzetea (rice paddies).

Representatives: nodding bur-marigold (Bidens tripartita), radiant beggarticks (B. radiata), pale persicaria (Polygonum lapathifolium), sea dock (Rumex maritimus)