A pupil of Pier Andrea Saccardo, Alessandro Trotter (1874-1967) is among the major figures in the discipline of ‘cecidology’, which studies the formation of galls. Donated to the University of Padua in 1954, the cecidological herbarium compiled by Trotter is organized alphabetically by host plants in 43 cardboard folders. Dried specimens are preserved mainly in paper envelopes. Mounted on each sheet are several specimens of the same species, with information on their provenance, the date of collection and the gall agent.

Assembled between late 1890 and 1940, the collection reflects the breadth of the cecidologist community, thanks not least to contributions from both Italian and foreign correspondents. Some notable names appear among the scholars who sent in specimens: A. Fiori, G. Cecconi, A. Forti, the van Leeuwen couple, E. Mameli Calvino, O. Jaap and Hieronymus et Pax. Three additional files include specimens of mycocecids, gall fungi and ‘double galls’. The donation also included various types of cecidological herbaria, designed for sale or exchange between research institutes, like the Cecidotheca italica, prepared by Trotter himself between 1900 and 1918, with the help of G. Cecconi; the Cecidotheca Fennica by T.J. Hintikka; two Romanian collections, Cecidotheca Dacica and Cecidotheca Romanica; the Sammlung Nied. Ost-Indischer Gallen by W.M. Docters van Leeuwen, and the collection Zoocecidia et Cecidozoa, by A.Y. Grevillius and J. Niessen.