54 MASS. EXPERIMENT STATION BULLETIN 345 



open after the leaves in June along with those of R. calendulaceum. Rated as 

 the best of the native white Azaleas. 



Rhododendrom arbutifolium — See Rhododendron, Alpine Rose Hybrids 



RHODODENDRON CALENDULACEUM (Azalea calendulacea) 



Flame Azalea 

 A native decidous shrub with a possible height and spread of ten feet. In 

 the wild its flowers, which are generally thought of as orange and about two 

 inches across, come about one to two weeks after those of R. roseum. Wild 

 plants of this species show individual flower-color variation from yellow to 

 scarlet as well as variations in size and form of flower. It is one of the parents 

 of the Ghent Hybrid Azaleas which despite larger flowers could, for the Ameri- 

 can garden, be dropped in favor of selected clons of this wild parent plant. 



Rhododendron canadense (Rhodora canadensis) RhODORA 



A low (one to three feet), somewhat gaunt inhabitant of moist woods 

 or swamps which, though lacking the garden value of many other species, 

 has a definite place in wild, informal planting because of bud hardiness of its 

 May flowers, and sentimental association. 



RHODODENDRON CAROLINIANUM Carolina Rhododendron 



As seen in cultivation, this evergreen species is a broad, compact shrub some 

 four or five feet in height. Foliage is relatively small and of reddish cast in 

 winter. The flowers, usually pink, appear in late May. With white flowers 

 and of somewhat less vigor, var. ALBUM is rated by some as having greater 

 garden value than the type. Both forms are satisfactory for forcing. 



RHODODENDRON CATAWBIENSE Catawba Rhododendron 



A handsome, hardy, large-leaved, evergreen species growing ultimately to 

 some six to ten feet in spread and height. Its only unsatisfactory property 

 is the purplish flower color which limits its use in garden groupings. Its better 

 features of habit and foliage have been transmitted to numerous, often less 

 hardy, hybrids of more pleasing and usable floral color. Of slow growth and 

 compact habit, var. COMPACTUM is a distinct natural strain discovered by Mr. 

 Harlan P. Kelsey. 



RHODODENDRON, EVERGREEN HYBRIDS 



The following list gives the combined opinion of many New England ob- 

 servers as to the more dependable and pleasing of the numerous garden hy- 

 brids: "album elegans", late white flowers; "ATROSANGUINEUM", 

 early red; "BOULE DE NEIGE", early white; "CATAWBIENSE 

 ALBUM", white; "Charles dickens", red; "DELICAtissimum", rose- 

 tinged white; "EVERESTIANUM", lilac; "LADY ARMSTRONG", 

 rose; "MRS. CHARLES SARGENT", deep rose; "PURPUREUM 

 GRANDIFLORUM", purple. 



X Rhododendron gandavense GHENT HYBRID AzALEAS 



This group includes a host of neat-growing garden varieties, most of which, 

 because of lack of hardiness, have not come into garden use in New England. 

 Apparently, success with their outdoor culture is dependent more on ample 

 moisture supply during the normally dry periods of summer than on degree 

 of winter cold. Own-root plants are considered to be superior to grafts. Mr. 

 P. M. Koster, writing in House and Garden Magazine, suggested the following 

 list for trial ; "Daviesii", large single white flowers; "Duicinee", single salmon- 

 red with yellow blotch; "Pallas", single red; "Unique", single, deep, bright 



