Testing flora as bioindicator of buried structures in the archaeological area of Maxentius's villa (Rome, Italy)

► Buried masonries create discontinuities in ground influencing flora that grows above. ► The bioindication of this phenomenon occurs on a floristic scale in several ways. ► Presence/absence of some species, decrease in number of individuals and plant cover. ► Phenological irregularities in single specimens with reductions in height and vigour. ► Spontaneous flora can be utilized as bioindicator in archaeological prospection.