Radó Dezső: Parks and Forests - Our Budapest (Budapest, 1992)

ly deteriorating slopes always have certain places, microclimatic niches, where plants other than those adapted to the actual climate grow and where relics from past climatic eras survive. At times of climatic change a short migration of several metres enables a plant species to make its way from a northern slope to a southern one or vice versa. Some relic species can be best preserved on dolomite, which is a rock with special characteristics. Species survived periods of adverse climatic conditions on the hillsides and spread to the plains only at times of favourable climatic changes.

The bedrock of the area, the refuge of ancient plant species, is the easily crumbling dolomite. The bulk of this was produced by the accumulation of masses of calcareous algae. The most characteristic fossil is Di- plopora annulata, a calcareous alga which at some places occurs frequently in the rock. On the dolomite of the Szénás Range a varied topography with dissected relief developed which permitted the formation of different microclimates within a relatively small area.

Most of the Kisszénás nature reserve is occupied by loosely closed rocky grasses and more tightly closed steppe meadows. On the northern slopes species characteristic of high mountains are found. The most valuable herbaceous species of the area is Pilis flax or dolomite flax. This tiny perennial plant which blossoms in May is widespread on the Szénás Range. Additional rare plants known from Kisszénás are spurge-flax daphne, bitter milkwort, button rampion, heath sedge, and the small moonwort growing.in the wet spots.

The sister of Kisszénás is the smaller (22 hectares) but higher Nagyszénás. The elevation of Kisszénás is 431 m, while that of Nagyszénás is 551 m.

The two cliffy, steep ridges and two larger valleys of the north side of Nagyszénás are protected. Their valuable flora includes the purple fescue grass, a relic from the Ice Age which is rare elsewhere but abundant here. Its nearest occurrences are in the Eastern Alps and in the lower alpine belt of the Northern Carpathians. Further curiosities are the variegated bent-grass, the grey thistle, which is common in the Tatras but is an Ice Age relic here, and the thermophilous Hungarian meadow saxifrage.

Below the cliffs of the northern ridges white oak, flowering ash, and mixed beech forest grows. The endemic species of the Buda Hills, the mountain ash of Buda also occurs here.

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