168 THE AZALEAS OF NORTH AMERICA 



Rhododendron arborescens is most nearly related to R. viscosum, but is easily 

 distinguished from this and other Azaleas by the glabrous branchlets, glabrous 

 leaves glaucous beneath and the large white or pinkish flowers. It shows little 

 variation except in the length and shape of the sepals, in the amount of pubescence 

 on the outside of the corolla, in the pubescence of the pedicels occasionally quite 

 or nearly glabrous, in the pubescence of the style, which is glabrous or sometimes 

 more or less pubescent below. 



Rhododendron arborescens was probably discovered by John or William Bartram 

 and appeared, according to Pursh, in Bartram' s catalogue as Azalea arborea, while 

 in the catalogue issued by Robert Carr in 1814 it appears as A. vertidllata; also 

 "Azalea caroliniana, Sweet Honeysuckle," in an undated "Catalogue of American 

 trees and shrubs ... in John Bartram's Garden" may possibly be the same 

 species. Also Humphrey Marshall seems to have known it, for his Azalea viscosa 

 (Arbust. Am. 15 [1785]), which he describes as a shrub five or six feet high growing 

 in rich rocky places near streams of water, is probably R. arborescens, while his 

 A. viscosa palustris is the true R. viscosum. 



Michaux observed it in May, 1795 (see his Jour. ed. Sargent, 116), on the Blue 

 Ridge in North Carolina, but there seems to be no specimen of it in his herbarium. 

 Loddiges, who published an excellent colored plate of this species under the name 

 Azalea vertidllata, states that it was received "many years since from our old 

 friend Bartram under this name," which tends to show that it was introduced 

 before the plant was known as A. arborescens and before 1818, the date given by 

 Sweet in his Hortus Britanicus under A . arborescens as the date of its introduction 

 to England, but neither Sweet nor Loudon say who introduced it at that date; 

 probably it was John Lyon, who was an active collector in North America up 

 to that time. It was first described in 1814 as a new species by Pursh, who dis- 

 covered it on the Blue Mountains of Pennsylvania, and also saw it cultivated in 

 John Bartram's garden at Philadelphia; he called it the finest ornamental shrub 

 he knew. It certainly is a very handsome shrub and it seems strange that it is 

 still so little known in cultivation; the dry leaves have a very pleasing smell of 

 coumarin, like Melilotus and Anthoxanthum, and retain it for many years in her- 

 barium specimens. 



Rhododendron arborescens var. Richardsonii Rehder, var. nov. 



A typo praecipue recedit statu humiliore plerumque 0.60-1.5, rarius ad 2.5 m. 

 altum, foliis paulo minoribus et magis glaucescentibus, corolla densius villosa et 

 magis glanduloso-hirsuta, sepalis plerisque brevibus ovatis vel semiorbicularibus 

 extus villosis, stylo plerumque in triente inferiore dense villoso. 



NORTH CAROLINA. Macon County: on Wayoh Bald, alt. 5200 

 feet, June 7, 1919, T. G. Harbison (No. 170, type, compact shrub, 

 4 feet tall, growing in dense patches), alt. 4800 feet (No. 176); High- 

 lands, on mountain side in moist soil, alt. 4400 or 4500 feet, June 23, 

 1918, T. G. Harbison (Nos. G 34, D 42); alt. 4000 feet, July 9, 1918, 

 T. G. Harbison (No. 62) ; without precise locality, alt. 3800 feet, July 2, 

 1911 (No. 655); high mountains, Sept. 2 and 6, 1910 (Nos. 114, 132), 



two different species, one being R. arborescens. If the locality, which is not clearly 

 written, is Pointclear, Baldwin County, the range of R. arborescens would extend 

 to the coast of Alabama, but until the occurrence of the species there is confirmed 

 by other collections I consider it doubtful. 



