150 JOURNAL OF THE ARNOLD ARBORETUM [vol. ii 



is of hybrid origin, sliould he referred as a synonym to P. nivalis Jacques, 

 which I take to represent a hybrid between P. pubescens and P. coro- 

 nanus and wliich then would be the vahd binomial for tliis hybrid. 



AZALEA OR LOISELEURIA 



Alfred Rehder 



Even if Azalea in tlie sense of Desvaux and modern authors is not con- 



sidered a distinct genus, the correct application of the generic name Azalea 

 of Linnaeus is a question to be decided, if the name of a subgenus or sec- 

 tion of Rhododendron is to be based upon it. It was therefore necessary 

 for me, when preparing an account of the American species of Rhodo- 

 dendron with deciduous leaves, to arrive at a definite conclusion as to 

 the species which should be considered the type of the genus Azalea, If 

 we follow up the history of the genus we find no change of the Linnaean 

 conception of 1753 of Azalea until 179C, when Salisbury recognized the 

 close affinity of most of the Linnaean species of Azalea with Rhododen- 

 dron, restricted the genus Azalea to A, prociiinhens and referred the 

 other species as far as he had to deal with them, including Rhodora' to 

 the genus Rhododendron, thus using the genus Rhododendron in the 

 same conception as proposed later apparently independently by D, Don 

 and accepted by Torrey, G. Don, Maximowicz and others. In 1813, 

 however, Desvaux had made another attenii>t to split up the genus Aza- 

 lea by removing A. procumbcns and making it the tyi)e of his new genus 

 Loiscleuria. In doing this he paid no attention to Linnaeus' original 

 description of the genus (Gen., 53 (1737), cd. 5, 75 (1754)) which api)lics 



exactly to A. procumhcns except the description of the capsule, which 



Linnaeus apparently had not seen, as he did not describe or figure it in 

 his Flora Laj)ponica, where he gives a description and figure of A, pro- 

 cumhei^s and also of A. Japponica, He took the description of the cap- 

 sule i)robably from the figure of Tournefort's Chamaerhododendron (Inst, 

 t. 373), which is cited as a synonym of Azalea in the first edition of Genera 

 plantarum, but omitted in the second and which rea])pears in the fifth 

 edition as a synonym of Rhododendron. He apparently had found when 

 working out the species for his Species plantarum that RJwdodendron 

 ferrugineum had 10 stamens and not 5, as seems to be tlie case in Tourne- 

 fort's figure. As the genus originally was based on A. procumhcns and 

 A. lapponica which were at that time the only species Linnaeus was well 

 acquainted with, it is clear that one of them must be the type of the 

 genus, and as the generic description in Genera plantarum fits A, pro- 

 cvmhcns, but not A. lapponica, the former must be considered the type 

 of Azalea. The fruit was first correctly described and figured witli three 

 cells by Gaertner in 1788, but the erroneous impression that the fruit was 



^ This geuus hu<I heen united already five years before with Rho.h)i!endron by F. S. Gmeliii 

 in t!ie thirteenth edition of the Systema naturae (u. pt. 1, G94). 



