CONTRIBUTION TO THE FLORA OF ZURICH .2. M ONOCOTS

''Flora of the city of Zurich'' includes 350 monocot species. 28 of th ese are frequent ergasiophytes and ephemerophytes which scarcely sprea d within the area. Only about half of the remaining 322 species are no t endangered, 45 (14%) are extinct (Ex), 69 (21%) endangered (E), and 48 (15%) vulnerable (V). Five systematic groups may be distinguished i n respect to their dynamics: A) families with predominantly water and fen plants; B) Cyperaceae and Juncaceae; C) Gramineae (Poaceae); D) Li liaceae, Amaryllidaceae, Iridaceae, Dioscoreaceae; E) Orchidaceae. The group D is characterized by the highest percentage of neophytes (37%) , the highest percentage of species increasing in frequency (50%), the lowest percentage of endangered as well as vulnerable and extinct spe cies (18% and 10%, respectively), and the highest degree of urbanity. On the other hand, neither neophytes nor species increasing in frequen cy are represented in group E. However, 22% of the species of this gro up are extinct and 52% vulnerable or endangered. The degree of urbanit y of the species is very low. It is important to the conservation and promotion of the endangered plants to protect the few remaining areas with a high species diversity (Uetliberg, Katzensee, Wehrenbachtobel). On the other hand, many smaller less spectacular areas containing rar e species should also be preserved. Open sites, e.g., gravel places, n ot-sealed parking lots and industrial areas, road sides, stone walls, railway escarpments are, too, favourable compensatory sites for weeds and pioneer plants.