160 THE AZALEAS OF NORTH AMERICA 



which belongs to var. glaucum and a specimen from Fayetteville, North Carolina, 

 Biltmore Herb. (Nat. Herb. No. 969,586) which belongs to var. nitidum. Several 

 forms and varieties have been distinguished but on account of their mostly in- 

 sufficient description and in the absence of type specimens it is not always pos- 

 sible to recognize them with certainty and the numerous intermediate forms make 

 their distinction still more difficult. 



Rhododendron viscosum was apparently first observed by John Banister, an 

 English missionary who sent a drawing of it to Dr. Compton, Bishop of London. 

 Dr. Compton communicated it to Plukenet, who published it in 1691 in his Phyto- 

 graphia. The plant was introduced into England apparently in the first half of the 

 18th century by John Bartram, who sent seeds or plants to Peter Collinson, 1 but 

 the exact date is not known. According to Aiton it was introduced in 1734, but 

 Catesby in 1731 speaks of this shrub in the text to the figure of his Cistus vir- 

 giniana, which is R. canescens, as "having for some years past produced its beau- 

 tiful and fragrant blossoms at Mr. Bacon's at Horton and at Mr. Collinson's at 

 Peckham." I suppose Catesby confused several species, as appears from the fact 

 that he applied Plukenet's name belonging to R. viscosum to his figure which repre- 

 sents R. canescens. His reference to fragrant blossoms seems to indicate that the 

 shrub in cultivation was R. viscosum. In any case this species must have been 

 well known about 1789 when Aiton enumerated five different varieties in cultiva- 

 tion. Wangenheim in 1787 published the first detailed description and char- 

 acteristic figure; he mentions three varieties observed by him in the state of New 

 York. 



From the type (R. viscosum a. odoratum Sweet, Hort. Brit. ed. 2, 344 [1830]. — 

 Azalea viscosa a. odorata Aiton, Hort. Kew. I. 203 [1789]. — Azalea viscosa a. viretu 

 Michaux, Fl. Bor.-Am. 1. 151 [1803]), which has green leaves and the flowers white 

 or sometimes striped pink outside along the middle of the lobes (Azalea viscosa 0. 

 vittata Aiton, Hort. Kew. 203 [1789]. — Rhododendron viscosum p. vittatum Sweet, 

 Hort. Brit. ed. 2, 344 [1830]), the following varieties and forms may be distinguished: 



Rhododendron viscosum f. rhodanthum Rehder, forma nova. 

 A typo recedit floribus intense roseis. 



Maryland. Prince Georges County: opposite Hyattsville, 

 eastward, May 31, 1915, E. S. Steele (Nat. Herb. No. 835,633). 



District of Columbia. North of Washington, June 15, 1909, 

 Professor Cook (Nat. Herb. No. 615,776). 



This is a form of the typical variety with bright pink flowers very glandular 

 outside. In the type specimen, which is from a low stoloniferous shrub, the very 

 young winter-buds are glabrous outside; in Professor Cook's specimen they are 

 silky-pubescent. This bright pink form occurs occasionally with the type, but 

 seems to be less common than the pink form of var. glaucum. 



Rhododendron viscosum var. glaucum Torrey, Fl. U. S. I. 425 

 (1824). — Gray, Syn. Fl. II. 1, 41 (1878). — J. Robinson, Fl. Essex 

 Co. Mass. 73 (1880). —Dame & Collins, Fl. Middlesex Co. Mass. 62 

 (1888). — Britton, Cat. PI. N. Jersey, 162 (1889). — Coulter & Wat- 

 son, Gray's Man. ed. 6, 320 (1890). —Dudley & Thurston, Cat. PI. 



1 See R. nudiflorum on page 136. 



