Raoul was related to, and probably studied with, the well known American still life artist Paul de Longpré.   It is interesting to note that the works of these two artists are often confused and their familial ties remained uncertain for many years.  William Gerdts and Russel Burke, in their catalog of American Still Life Paintings (London: Praeger Publishers), refer to Paul and cite:

His (Paul’s) work had depth of space and richness of color as does that of his son Raoul de Longpre, and his daughters, all of whom followed their father in the field of flower painting.

James J. White, in his article Raoul M. de Longpre fils, elusive painter of lilacs and roses, indicates the confusion surrounding the relationship between Paul and Raoul when he states:

Paul was born in Lyons in 1855, the son of Victor and Therese de Longpré.  His father, two brothers and an uncle (could this have been Raoul, who may have encouraged Paul’s journey to America) were also painters.

On several occasions paintings that bear Raoul’s signature have been ascribed, by experts, to Paul.  It is the opinion of several art scholars that the greatest truth about their relationship lies in the likeness of their superb floral watercolors – evincing a high degree of scientific knowledge and decorative ability.

Today it is widely believed that Raoul was Paul’s older brother, sons of Jean-Antoine-Marie-Victor and Marie-Therese Pinchaud de Longpré, and that the two were living in Paris during the late 1870s.  Paul moved to the United States in 1890 and it appears that Raoul continued to live in France.

Raoul’s painting Roses, in the collection of the National Museum of Art, Smithsonian Institution, Washington D.C., displays his very successful formula which James J. White as a … bouquet of lilacs and/or roses floating in space or surmounting a plinth, rendered in delicate watercolor with an inchoate background on the left side.