Did Plant Patents Create the American Rose? by Petra Moser and Paul W. Rhode p. 418 (in The Rate and Direction of Inventive Activity Revisited (2012) By Josh Lerner, Scott Stern)

Patent examiners were especially lenient in granting patents for nursery stock that Luther Burbank had developed with financing from Stark Brothers and that was owned by Stark Nurseries after his death (Allyn 1944, 54). In 1933 alone, the USPTO granted nine patents to Burbank's estate, including two for roses (PP65 and 66, Burbank's Apple Blossom and Burbanks 'Golden Sunset), four for plums, two for peaches (PP12, 13, 14, 15, 16, and 18), and one for a new variety of cherry (PP41). As late as 1937 and 1938, the USPTO granted PP235 for Burbank's Golden Comet (in 1937) and PP266, PP267, and PP269 for Burbank's Copper Climber, Burbank's Snow White Climber, and Burbank's Dawn Glow (in 1938). None of these posthumously patented roses became commercially important (Terry 1966).