The purpose of this critical study is to examine the young Hugo von Hofmannsthal’s theory of form departing from the characterization that Kurt Breysig provides of his poetry as Treibhauskunst, that is, greenhouse art. It aims also to illustrate how Hofmannsthal finds in the theoretical developments of Gottfried Semper the most precise expression of his own concept of form. The main point of the paper is to show that, at the turn of the twentieth century, the metaphorization and the (...) figuration of the greenhouse derives from its architectural features both formal means and aesthetic attributes closely linked to moral values. (shrink)