L. Lőkös szerk.: Studia Botanica Hungarica 24. 1993 (Budapest, 1993)

Stollmayer-Boncz, Emilia: The flora of Réti-dűlő near Csömör

STUDIA BOTANICA HUNGARICA (Antea: Fragmenta Botanica) XXIV. 1993 pp. 27-44 The flora of Réti-dűlő near Csömör By E. Stollmayer-Boncz (Received November 20, 1992) Abstract: The Réti-dűlő occupies the major part of the Csömöri-legelő nature reserve designated as a county park in 1977. The drying swamp meadows provide asylum for Molinion coeruleae, whereas the reeds is a refuge for seven other protected or endangered species (Carex appropinquata, Dactylorhiza incarnata, Epipactis palustris, Eriophorwn latifolium, Iris pseudacorus, Orchis laxiflora subsp. palustris, and Parnassia palustris). This review provides the first set of botanical data of the area, serving as a basis for further studies. INTRODUCTION The Csömöri-legelő (pasture) is a nature reserve protected by the Pest County. It is near the village of Csömör, in the valley of Forrás brook (also called Csömör brook). The area has been botanically unexplored until 1977. It lies on the Pesti Plain which forms the northern part of Dunamenti Plain which in turn is divided by fan terraces resulting in significant relief. The Forrás brook is a low discharge Tertiary tributary on the left bank of the Danube. It flows into the Mogyoródi brook, which in turn is a right tributary of the Szilas brook. The Forrás brook has its source on the side of the flood-free Terrace V of the Danube and flows through the village of Csömör lying east of the study area. The valley is located on the Middle Pleistocene Terrace III of the Danube, north of the flood-free Terrace IV, 34 m above the 0 level of Danube (Map 1). The Réti-dűlő study area slopes towards the Danube dropping in elevation from 150 m to 140 m above sea level (with reference to the Baltic Sea) (Map 2). Hay fields, reeds, creekside and meadow willow groves are found in the brook valley what is covered by meadow and swamp soils. The meadow is bordered on the left by intermittent locust groves along the road, cultivated fields lie further on. Also on the left, in the middle of the area lies the Csömör pool. Results of the botanical study of this area have already been published (STOLLMAYER-BONCZ 1982, 1988,1993). The northwestern part of the study area is occupied by a sandy knoll (elevation 160 m) with a cultivated field on the top and locust forests on the side. Other parts of the valley beyond the protected area are also cultivated. A strip of the right bank is separated by a road from the wheat fields of Káposztások Knoll (167 m). On most areas towards the village there are high sedgy, reedy, and willowy patches. An artificial fishing lake has been developed in the major part of this area. Regarding the geology of the area, it has no adverse effects on the local water supply. From phytogeographical point of view, the study area forms part of the Praematricum subregion of Eupannonicum region of Pannonian floral province (Pannonicum). The nature reserve is botanically unexplored, except for the area around the Csömör pool. Although botanical data on the flora of the Rákos and Szilas brook valley have been published by several authors (the first record by BORBÁS dates back to 1879), the plant assemblages of 27