Webern published little of his early work in particular; like Brahms, though perhaps for not entirely the same reasons, Webern was characteristically meticulous and revised extensively. Many juvenilia remained unknown until the work and findings of the Moldenhauers in the 1960s, effectively obscuring and undermining formative facets of Webern's musical identity, highly significant even more so in the case of an innovator whose music was crucially marked by rapid stylistic shifts. Thus when Boulez first oversaw a project to record "all" of Webern's music, not including the juvenilia, the results fit on three rather than six CDs.  Webern's earliest works consist primarily of lieder, the genre that most belies his roots in Romanticism, specifically German Romanticism; one in which the music yields brief but explicit, potent, and spoken meaning manifested only latently or programmatically in purely instrumental genres; one marked by significant intimacy and lyricism; and one which often associates nature, especially landscapes, with themes of homesickness, solace, wistful yearning, distance, utopia, and belonging. Robert Schumann's "Mondnacht" is an iconic example; Eichendorff, whose lyric poetry inspired it, is not far removed from the poets (e.g., Richard Dehmel, Gustav Falke, Theodor Storm) whose work inspired Webern and his contemporaries Alban Berg, Max Reger, Arnold Schoenberg, Richard Strauss, Hugo Wolf, and Alexander Zemlinsky. Wolf's Morike-Lieder were especially influential on Webern's efforts from this period. But well beyond these lieder alone, all of Webern's music may be said to possess such concerns and qualities, as is evident from his sketches, albeit in an increasingly symbolic, abstract, spare, introverted, and idealized manner.  Other works include the orchestral tone poem Im Sommerwind (1904) and the Langsamer Satz (1905) for string quartet.  Webern's first piece after completing his studies with Schoenberg was the Passacaglia for orchestra (1908). Harmonically, it is a step forward into a more advanced language, and the orchestration is somewhat more distinctive than his earlier orchestral work. However, it bears little relation to the fully mature works he is best known for today. One element that is typical is the form itself: the passacaglia is a form which dates back to the 17th century, and a distinguishing feature of Webern's later work was to be the use of traditional compositional techniques (especially canons) and forms (the Symphony, the Concerto, the String Trio, and String Quartet, and the piano and orchestral Variations) in a modern harmonic and melodic language.

Answer this question "how was he rooted in Romanticism?" by extracting the answer from the text above.
one in which the music yields brief but explicit, potent, and spoken meaning manifested only latently or programmatically in purely instrumental genres;