The sedge family, with about 5,500 species and 90 genera worldwide, is the third largest family of monocots. The unique combination of morphological and karyotypic features contributes to rapid evolution and diversification, as well as high levels of endemism in some groups.
Morphological features and characteristics of the family
Sedge looks like grass. More and more evidence is known that the closest relatives of sedges are rushes. Both families have chromosomes with a very peculiar structure. Centromeres, the points of attachment of spindle fibers during meiosis, are not localized in one place near the middle, but are distributed diffusely along the length of the chromosomes. Both sedges and rushes have pollen that disperses in the form of tetrads. Both families also have the same number of leaves per row.
Sedge stems are often triangular, mostly solid, while grass stems are never triangular - they are usually hollow. Most sedgehave a morphological appearance of herbaceous perennial plants with fibrous roots, triangular stems and three-row leaves. Many species have rhizomes of different lengths; in a number of them, rhizomes are important organs for storing nutrients. Sedges range in size from tiny plants less than 1 centimeter tall to giant papyri that can reach up to five meters.
Classification of sedge
Modern classification systems divide the sedge family into 2-4 subfamilies. The division of the family into two subfamilies would result in the subfamily Sytaceae (usually with hermaphroditic flowers) and the subfamily Sedge (with unisexual flowers). However, many botanists consider this division rather abstract.
Scientists divide sedge into four subfamilies in this way:
- Sytye. This is the largest subfamily, containing about 70 genera and 2400 species. Representatives usually have ideal flowers in simple spikes with often numerous spirally arranged or two-row scales.
- Sedge subfamily Caricoideae. The next largest subfamily has 2100 species, scattered among only 5 genera, and is characterized by unisexual flowers in spikelets enclosed in shoots.
- The subfamily Sclerioideae contains about 14 genera and 300 species; its flowers are also unisexual, but the fruit is not covered by a similar shoot.
- Subfamily Mapanioideae. There are about 170 species in 14 genera. The strongly reduced unisexual flowers are densely grouped in such a way as to mimic a single flower, the so-calledpseudonthium.
Distribution and diversity
Sedge contains about 5000 species and, depending on the classification used, from 70 to 115 genera. Plants are distributed over all continents except Antarctica. While a large number of species exist in arctic, temperate, and tropical regions, the diversity of genera is much greater in tropical regions. Many sedge species found in northern latitudes have a circumpolar distribution. Species found in tropical or warm temperate regions, other than those that are widespread agricultural weeds, are generally restricted to one continent.
The ecological diversity of sedge is huge: species are found in almost all habitats, except for extreme deserts, marine and deep-sea ecosystems. Most species of the sedge family, however, are plants of sunny or moist habitats (fresh and s alt marshes, pond and lake shores, grasslands, wet prairies and savannahs, and wet tundra). Species that prefer sunny areas can also be found in artificially created habitats such as ditches and canal banks. Many varieties of sedge are found in the undergrowth of various types of forests (both temperate and tropical). Some are adapted to specialized habitats, including sand dunes, freshwater lakes and streams, and rocks.
Below are some representatives of the sedge family, most of which grow everywhere in Russia:
- bulrush;
- cobresia;
- common sword grass;
- sedge;
- cotton grass;
- schenoplexus;
- full;
- fimbristilis;
- cyperus.
Family Ecology
The ecological importance of sedge is unusually high. They are often the dominant components of many biomes. Thus, they are critical to primary productivity and many aspects of the continuous circulation of water in the atmosphere, i.e. evaporation, transpiration, condensation, precipitation, and runoff. Fruits, and sometimes shoots, as well as tubers of sedges are an important food for many aquatic and amphibious animals. Large stands of sedges are also critical as hiding places for many mammals.
Sedges are not only important components of sustainable swampy soil communities, but also play an important role in their succession. Many species of annual and perennial sedges are the first colonizers on the lifeless soil of newly created biomes. In mature swampy soils, these species are replaced by perennial representatives. Sedge seeds can be introduced to new habitats by dispersal, usually by birds. However, many species, especially those that undergo cyclic periods of desiccation, have "dormant" viable seeds that persist in the soil as a seed bank. The vegetation of such soils is rejuvenated from the seed bank toappropriate conditions, rather than relying entirely on resettlement.
Economic importance
The sedge family cannot boast of a large number of types of useful crops. Of these, by far the most important are the Chinese water chestnut and chufas or tiger nuts, varieties of yellow walnut sedge grown predominantly in Africa. In both species, the edible parts are underground tubers. In boreal and mountainous regions, sedge species are often important grazing plants and may even be cultivated, such as the meadows of some sedge species in Iceland.
Worldwide, many sedge species are of regional importance in basket weaving, screen making, and even sandals because of their tough, fibrous stems and leaves. Such plants are cultivated in India. Indigenous peoples on Lake Titicaca in the Andes use sedge to build small boats called balms. Some large, fast-growing wetland sedges are grown in ponds and domestic wastewater treatment tanks for their ability to absorb excess nutrients, particularly phosphorus and nitrogen.
