Nieuwe vondsten van zeldzame planten in 1997, 1998 en 1999

In the 20th century ca. 50 species disappeared; ca. 80 species became fully naturalized, 20% of which without any form of human interference. The greatest losses are among weeds and among species from nutrient poor, weakly acid habitats. Woodland species clearly increased, and the explosive urbanisation led to new niches for a number of species, even so that we now distinguish an “urban district” for plants. The present list contains a nice number of new records of very rare plants: Anacamptis pyramidalis, Apium repens, Blackstonia perfoliata s.s., Carex laevigata, Centaurea calcitrapa, Circaea alpina, Crepis foetida, Equisetum telmateia, Equisetum variegatum, Filago vulgaris, Huperzia selago, Hypericum canadense, Moneses uniflora. Totally new is Marsilea quadrifolia. Some species, thought to be extinct, were found on new localities: Callitriche palustris, Elatine hydropiper, Eleocharis ovata, Lathraea squamaria, Oenanthe pimpinelloides and Oenanthe silaifolia. """"Nature development"""" projects sometimes showed recovery of interesting and rare plants: Anagallis tenella, Hypericum montanum, Juncus capitatus, Juncus pygmaeus, Juncus tenageia, Lycopodiella inundata, Ophrys apifera, Pinguicula vulgaris, Samolus valerandi and Viola persicifolia. Peculiar is the record of Artemisia biennis as a halophyte. Possibly new is the observation of Artemisia campestris subsp. maritima as the host of Cuscuta epithymum.