Survey of Extremely Endangered Taxons in the Flora of Serbia Which Live in the SNR Zasavica
During the research of aquatic macrophites in the Reserve 45 taxons have been found so far. Among the macrophites in the Reserve cosmopolitan species highly dominate the area – they make over 90% of the macrophites. From the complete diversity of the Reserve the presence of rare and extremely endangered taxons is considerable.

For the previous period of research in the area of the Reserve some extremely endangered species of flora of Serbia have been recorded:
Hippuris vulgaris. L.
Hippuris vulgaris L. (fam.Hippuridacrae) is aquatic perennial plant, half immersed into the water. It is connected to the bottom with its rhizome which can be 190cm long. The stem is straight, firm, cylindrical and up to 45cm tall (very rarely to120cm). The leaves are linear and linear-lancet shaped put in a vertebrate order. Lower, submersed leaves are dark and directed to the bottom, middle leaves are thinner, horizontal and upper leaves are light green directed to the surface. The flowers are small, placed under the armpit of a leaf and the fruit is green, egg-shaped nut.

The habitat of this plant is in stagnant and slow-flow waters, small lakes, swamps, sandy and clay river banks and reed beds. Area of this species includes arctic, boreal and temperate areas of Europe (as far as Island and North Norway), Greenland, western Asia, North America, a Antarctica part of South America and Australia.

Its spreading on the Balkan Peninsula is very limited. Taxon and fitographic importance of the species is that it is the only representative of oligotypic and circumholoarctic genus of Hippuris in Europe which includes two more species H.montana and H.tetraphylla. It is the relic of hydrophilic flora. In Serbia they can be found on the south edge of Europe . The species has been extinct from half (of 8 known) localities in Serbia in the last 50 years. In Zasavica region the first data about this species were published by Jurisic Z. (1911) and and its presence was confirmed in Banovo Polje in 1997/98 by the Institute for Protection of Nature in Serbia . This species, according to IUCN category for Serbia region, has the status of extremely endangered one (CR-Srb,B/2c) and for Yugoslav region, according to the same categorization, it has the status of endangered species (EN-Yu,B/2c).
Hottonia palustris - aquatic primrose, frog lily
Hottonia palustris (Fam. Primulaceae) is perennial aquatic plant with creeping root. The stem is up to 90cm long. It hangs in the water and it is cylindrical and shaped like a vertebra. There are a lot of long, white roots coming out of vertebras covered with curly, red hairs and comb-like leaves. Leaves are soft and spirally placed. The slices are linear, submersed and floating. Cluster of flowers is terminal, grapes-shaped with 3-9 blossoming vertebras above the water surface. The flowers are white, rarely pink, placed in the arm of bracteias of the same length as the stem. Calyx is of the same length as the tube of the crown. The fruit is multi-seed shell shorter than calyx and the seed is dark .

It lives in the slow-flow or stagnant waters (canals, ponds and swamps) where it creates monotypic community Hottonietum palustris or joins the community of Lemma. It is the part of swampy vegetation in the forests of Alnetea glutinosae class. It demands shady, wet or muddy habitats. It is an indicator for mezotrophic waters.

The living area of this species is middle Europe from the Atlantic coast in France and the British Isles to Ural and Kavkaz. The northern edge of this area goes to Scandinavia and Finland and the southern one goes to the Apennine and the Balkan Peninsula . The furthest edge in the south is the north-west part of Asia.
It is scattered in the western part ( Slovenia and Croatia ), central ( Serbia ) and eastern part of the Balkan Peninsula . It has been estimated that there are about 1000 specimens capable of reproduction in Serbia . Newly recorded habitats of this species do not point to its spreading but more to its disappearing. For the Zasavica region on Sumar bridge locality there are up to 100 specimens capable of reproduction.Taxonomic and fitographic importance of Hottonia palustris is its state of belonging to oligotype genus of Hottonia which includes North American species of H. inflate. These distant philogenetic relationships indicate the relic of the species. Its status for Serbia region is one of an extremely endangered taxon (CR-Srb,B/2ac) as well as for Yugoslavia (CR-Yu,B/2ac).
Ranunculus lingua L. - tongue-leaved crowfoot
Ranunculus lingua L. (Fam. Ranunculaceae) is a perennial plant with thick, porous rhizome and haired root. Its tendrils can be up to 80cm long. The stem is 50-150cm long, firm, straight, porous and branchy in the upper part with rare hairs. All leaves are narrow linear shaped with short stem 10-12cm long, pointed and grey-green. The flower is golden-yellow, 3-4cm wide. The fruit is egg-shaped, flattened on the sides. The beak of the fruit is wide, curved, smooth or, rarely, hairy. It grows on wet places: the edges of ponds and swamps. It lives in peripheral parts of Scirpo-Phragmitetum community where water is up to 50cm deep and usually dries up during the summer.

The living area is almost all Europe with the exception of the furthest South and North. The western edge of this area is the Atlantic part of Europe ( Ireland , England , France ), the northern edge is the Scandinavian Peninsula and west Siberia, the southern one is Sicily and the eastern one is western Mongolia.

Taxonomic and fitographic importance in the flora of Serbia is its state of belonging to Flammula section and Lingua series which includes only one more species of R. amurensis spread in the Far East. It can be easily distinguished from the other representatives of Flammula section and Ranunculus genus for its long lancet-shaped leaves and big flowers up to 4cm in the diameter. It is rather isolated in the system of Ranunculus genus by its philogenetic connections with its vicar relative in eastern Asia which indicates its relic, i.e. the state of belonging to the elements of Arctoterciar hydrophytes flora.
All habitats in Serbia are on the southern edge of the European living area. The localities in Serbia are mostly connected to Vojvodina and only a few of them to the south-east of Serbia . In the Zasavica region the first data about this species were published by Jurisic Z. (1911) and its presence was confirmed in 1996 by the Institute for Nature Protection in Serbia . Subpopulation in Zasavica is small. It lives on 100m2 and the number of specimens is restricted to 530 the half of which is in the phase of blossoming. This species, according to IUCN category for the Serbian region has the status of extremely endangered taxon (CR-Srb,B/2ac+3ab) and for the Yugoslav region, according to the same categorization, it has the status of endangered taxon (EN-Yu,B/2ac+3abE).
Centaurea sadleriana Janka - Pannonian knapweed
Centaurea sadleriana Janka (Fam.Asteraceae) is a perennial greenish plant up to 2m tall. Flowers are purple to pink red. It blossoms from June to October.

It is a Pannonian sub-endemic plant spread mostly in the Pannonian Plain. It grows on dry lowlands and hilly habitats covered with grass in the continental part. It is rather spread species in Vojvodina. Most of them are on Fruska Gora. It is very rare in SCG, but complete world population is so small that, although it has not been endangered yet, it may soon become one (R-Rare). According to the International Protection of Species it has been included into the European Red List of Endangered Plants, while in SCG it is not protected by law.