I just received the book “The Encyclopedia of Herbs” by Arthur Tucker and Thomas Debaggio. Great book with lots of interesting information.
According to the authors and in agreement with Millers (see previous entry) writings:
The true P. graveolens is similar to P. radens but it is not now in general cultivation. They state that the plant sold as P. graveolens is actually ‘Graveolens’. A member of the ‘Graveolens’ hybrids (P. capitatum x P. radens or P. graveolens. The older name that was once used is Pelagronium x asperum Willd. but close examination of Willdenow’s type specimen in Berlin reveals that the latter is a hybrid involving P. quercifolium or maybe P. panduriforme Eckl. & Zeyh.
Pelgonium ‘Graveolens’ have commonly be called ‘Old Fashioned Rose’, ‘Rose’. This ‘Graveolens’ is what is raised commercially on the island of Reunion.
The general chemistry of the essential oil from P. ‘Graveolens’ include:
8-51% citronellol, 1-28% citronellyl formate, trace to 23% geraniol, trace to 18 percent b-caryophyllene, 0-6% linalol and 1-10% geranyl butyrate. This agrees with research reports from Lawrence, 1989 and 1982, Jeon et al 2008 and Fayed S 2009.
So, I am feeling a bit more confident that I can assume when individuals are selling Pelargonium graveolens or Pelargonium x asperum they both are Pelargonium ‘Graveolens’ cultivars that offer a leafy-rosy-sweet-like aroma.
Thank you Tucker and Debaggio! Whew.