808 



HORTICULTURE 



June 13. 1914 



HARDY EVERGREEN RHODODEN- 

 DRONS. 



I From Bulletin No. 57 of the Arnold 

 Arboretum.) 

 The number of species of Rhododen- 

 drons with evergreen leaves which can 

 be successfully cultivated in this cli 

 mate is not large. The four species ol 

 eastern North Americft, Rhododendron 

 maximum. R. Cataicbiense. R. caroli- 

 nianum. and R. minus are all perfectly 

 hardy, as are R. Sminwuii and R. 

 raiicasicum- from the Caucasus, R. 

 - brachycarpum from Japan and R. 

 micrarithum from China. The flower- 

 buds of the last, however, have been 

 destroyed by the cold of the past 

 winter. The two European species, 

 R. ferrugineuin and R. hirsutum. are 

 not very satisfactory plants for thi.s 

 climate, and unless exceptionally 

 favorable positions can be found for 

 them they are not long-lived here. In 

 recent years R. maximum has been 

 largely planted in this part of th.= 

 country, but the common Rhododen- 

 dron of American gardens belongs tn 

 a race of hybrids which originated in 

 England many years ago and are 

 known as Catawbiense hybrids be- 

 cause they have been produced by 

 crossing R. Oataivbiense of the high 

 summits of tlie southern Appalachian 

 Mountains with R. ponticum of the 

 Caucasus, and with 7?. aibonum and 

 other Himalayan species. These hy- 

 brids are valuable in this country in 

 proportion to the influence on them of 

 R. Gataicbit'iise. and it is found that 

 varieties with broad leaves like those 

 of the American plant are always 

 hardier than the narrow-leaved varie- 

 ties which show a greater influence of 

 R. ponticum. and the Indian species. 

 The number of these hybrids, however, 

 which are really hardy in this climate 

 is not large; among them Atrosan- 

 guineum (very early), Cliarles Dick- 

 ens and H. W. Sargent (late) of red- 

 flowerej varieties are good plants; 

 among the pink-flowered varieties 

 none have proved so satisfactory as 

 Mrs. Charles Sargent and Henrietta 

 Sargent, similar in general appear- 

 ance, but the latter with smaller and 

 more compact flower-clusters and flow- 

 ers of not quite such a perfect pink. 

 Among the varieties with rose-colored 

 flowers, Roseum elegans and Lady 

 Armstrong are hardy and satisfactory; 

 and among the varieties with dark 

 purple flowers Purpureum grandiflo- 

 rum, Purpureum elegans and King of 

 the Purples are all hardy. Of the 

 varieties with light purple flowers 

 Everestianum is the best and one of 

 the hardiest and most satisfactory of 

 all these hybrids. Among the white- 

 flowered varieties Catawbiense album 

 (very early), Album elegans and Al- 

 bum grandiilorum can be safely used. 

 Most of the hybrid Rhododendrons in 

 American gardens are of English ori- 

 gin, but a few years ago the Arbore- 

 tum obtained in Germany a number of 

 these hybrids raised in that country. 

 These have proved very hardy and 



MOUNTAIN LAUREL. 



K.4.LMIA AND White Pines 

 Kalmia time is now with us and the 

 dainty flowers of this loveliest of 

 American broad-leaved evergreens are 

 seen in the wholesale markets in great 

 quantities. It is pleasing to see natural 

 growths of kalmia protected against 

 the cutting and slashing which is rap- 

 idly exterminating the plant in many 



localities. The accompanying picture 

 shows a bit of the extensive natural 

 woodland of white pines with under- 

 growth of kalmia, on the estate of 

 P. S. Moseley at Newburyport, Mass. 

 It is beautiful to contemplate at any 

 season of the year, but when in bud 

 and bloom it makes a picture never to 

 be forgotten. 



some of them promise to be valuable 

 additions to the Rhododendrons which 

 can be successfully cultivated here. 

 The most distinct, perhaps, are Viola, 

 with white flowers, Albert, with pale 

 pink flowers, and Bismarck, with 

 white flowers- with small brown dots 

 on the inner face of the cororia. The 

 last has flowered profusely now every 

 season for the last three years; the 

 foliage and habit are good, and as it 

 flowers early this variety is particu- 

 larly valuable, for there are not many 

 early white-flowered Catawbiense hy- 

 brids. Among the hybrid Rhododen- 

 drons which have been raised between 

 R. vataubiensc and R. maximum, the 

 best known is Delicatissimum. This 

 blooms later than the Catawbiense hy- 

 brids; it is a large plant, of good 

 habit, with long lustrous leaves and 

 pale pink and white flowers, and one 

 of the best Rhododendrons which can 

 be grown in this climate. 



The experience of another year con- 

 firms the good opinion which the Cau- 

 casian Rhododendron Smirnowii has 

 made for itself here. It is a large 

 plant with pale green leaves covered 

 below with a thick mat of nearly 

 white wool and large clusters of bright 



I More Red Devil Cutters Used Annually Than All Others Combined 



I SMITH & HErMENWAY CO., 



Send 6e. f*r lample N«. Oti 

 and Booklet 40 stylM, and 

 un<lerstand why. 

 SEND FOB BOOKLET ANY- 

 HOW. 



1«1 CHAMBSK8 ST.. MEW YOKK 



pink flowers. It grows best in partial 

 shade as the hot sun of our summer 

 causes the leaves to curl. A number 

 of hybrids have been obtained in 

 Europe by crossing this species with 

 some of the Catawbiense hybrids. 

 Some of these hybrids are established 

 in the Arboretum and have flowered 

 for several years, but the cold of the 

 past winter has destroyed their flower- 

 buds. Rhododendron caurasicum and 

 its hybrids or varieties should be more 

 often found in our gardens, in which 

 the form of this species known as 

 Boule de Neige is the only one usually 

 seen. Like the other forms of R. cati- 

 vasicum it is a small compact plant 

 which covers itself with clusters of 

 large white flowers which open earlier 

 than those of most of the Catawbiense 

 hybrids. This earliness, its good habit, 

 and its handsome pure white flowers 

 make this a desirable garden plant in 

 this climate. Another plant of this 

 race with pale yellow flowers, known 

 as R. coriaceum. is now in flower and 

 is also a hardy and desirable plant. 

 A smaller plant of this race, Mont 

 Blanc, is interesting as the flowers, 

 which are bright pink when they open, 

 become at the end of a day or two 

 pure white. On some of the dwarf 

 forms of R. caurasicum the flower- 

 buds have been injured this year for 

 the first time, but in spite of this 

 these plants can be recommended for 

 New England gardens. 



Rosn Hugonis has been in flower in 

 the Shrub Collection for the first time 

 in (he Arboretum. It is a native of 

 western China, with clear yellow 

 single flowers and neat pale foliage. 



