In 1855 Richard Deakin published a study of the wild flowers growing in and on the Colosseum in Rome. It is available online. There was an earlier study and there has also been done a recent study and what it allows for is a study of place through the study of plants. Deakin's book contains a list of plants with descriptions. In the preface he writes:
The object of the present little volume is to call the attention of the lover of the works of creation to those flocal productions which flourish, in triumph, upon the ruins of a single building. Flowers are perhaps the most graceful and most lovely objects of the creation but are not at any time, more delightful than when associated with what recalls to the memory time and place, and especially that of generations long passed away. They form a link in the memory, and teach us hopeful and soothing lessons, amid the sadness of by- gone ages : and cold indeed must be the heart that does not respond to their silent appeal ; for, though without speech, they tell of that regenerating power which reanimates the dust of mouldering greatness, and clothes their sad and fallen grandeur with graceful forms and curiously constructed leaves and flowers, resplendent with their gay and various colours, and perfume the air with their exquisite odours. The plants which we have found growing upon the Colosseum, and have here described, amount to no less a number than 420 species ; in this number there are examples of 258 Genera, and illustrations of 66 of the Natural Orders of plants, a number which seems almost incredible. There are 56 species of Grasses, 47 of the order Compositea or Syngenesious plants — and 41 of the Leguminous or Pea tribe.
The collection of the plants and the species noted has been made some years ; but, since that time, many of the plants have been destroyed, from the alterations and restorations that have been made in the ruins ; a circumstance that cannot but be lamented. To pre- serve a further falling of any portion is most desirable ; but to carry the restorations, and the brushing and cleaning, to the extent to which it has been subjected, instead of leaving it in its wild and solemn grandeur, is to destroy the impression and solitary lesson which so magnificent a ruin is calculated to make upon the mind.