The Colosseumʹs use and state of abandonment as analysed through its flora

Over the past four centuries, different lists of the flora of the Colosseum have been published (Jatrologismi sive medicae observationes quibus additus est in fine Plantarum Amphitheatralium Catalogus. Typis Dominici Marciani, Rome, p. 15; Enumeratio plantarum sponte nascentium in ruderibus Amphitheatri Flavii. Typis Pauli Salviucci et filii, Rome, p. 80; Flora of the Colosseum of Rome. London. p. 230; Florula del Colosseo. Atti Accademia Pontificia Nuovi Lincei 28, 20,7; 29, 33; 30, 8; 31, 13; Ann. Bot. (Roma) XXIII (fasc. 3) (1951) 393; Webbia 56(2) (2001) 321). The rich plant colonization (684 species, as the sum of the various lists) appears to be due to the great variety of habitats in the monument and to its state of abandonment. The comparison among the different floras allows a quantitative estimate of the following general changes to be determined: a gradual yet notable decrease of typical elements of mature dynamic stages; a constant decrease in species related to grazing and animal droppings, as well as in weeds from cultivated fields; and a constant increase of widely distributed and alien species, indicators of a different but ever stronger impact of man on the area.