June 10, 1911 



HORTICULTURE 



860 



RHODODENDRONS AT THE AR- 

 NOLD ARBORETUM. 



Frcirn Bulletin No. 6. 

 Many of the rhododendrons in the 

 collection at the base of Hemlock Hill 

 are now in flower and can be most 

 easily reached from the South street 

 entrance. Owing to the heat and 

 drought of May the flowers are small- 

 er than in more favorable seasons and 

 they will probably not last long in 

 good condition. 



The variety of these plants which 

 can be successfully grown In this 

 climate is not large, and they are 

 mostly derived from a few species. 

 The most important of these species 

 are three rhododendrons of the east- 

 ern United States — ^Rhododendron ca- 

 tawbiense. Rhododendron punctatum 

 and Rhododendron maximum. The 

 first grows only on the high summits 

 of the southern Alleghany mountains 

 where it sometimes covers enormous 

 areas, but is rarely found much below 

 an altitude of five thousand feet. 

 This plant is very hardy and in cul- 

 tivation forms a broad, low bush; it 

 grows slowly, however, and the flow- 

 ers are of a rather disagreeable pur- 

 plish rose color. ' It is most interest- 

 ing for the part which it has played in 

 the production of the principal race of 

 garden rhododendrons. Several plants 

 are now in flower along the drive not 

 far from the South street entrance. 

 The second species. Rhododendron 

 punctatum, is also a native of the 

 southern Appalachian region where it 

 grows at much lower altitudes than 

 Rhododendron catawbiense. It forms 

 a dense low bush with small leaves 

 thickly covered on their lower surface 

 with dark dots, and small, reddish 

 purple flowers in small compact clus- 

 ters which are a good deal hidden by 

 the young branches which, growing 

 before the flowers open, overtop them. 

 This plant, of which there are good 

 specimens in the collection, will not 

 be in bloom for several days. There 

 are two hybrids of this species known 

 in gardens as Rhododendron Wilsoni 

 or arbutifolium, and Rhododendron 

 myrtifolium. The former is a cross 

 with' the alpine Rhododendron ferrug- 

 ineum and the latter with the alpine 

 Rhododendron hirsutum. In habits 

 and foliage they are handsomer plants 

 than their American parent, and are 

 useful for small gardens and for the 

 margins of beds of larger plants; they 

 will not be in bloom for several days. 

 Rhododendron maximum, the third of 

 the American species, is found occa- 

 sionally in New England swamps and 

 is very common along the borders of 

 streams in mountain valleys south of 

 New York,' often gi-owing to the size 

 of a small tree and sometimes form- 

 ing impenetrable thickets of large ex- 

 tent. This is the latest of the rhodo- 



dendrons to' flower here and will not 

 be in bloom for several weeks. The 

 flowers and the flower-clusters are 

 much smaller than those of Rhododen- 

 dron catawbiense and, like those or 

 Rhododendron punctatum. they are 

 hidden by the branchlets of the year 

 which surround and rise above them. 

 A hybrid of Rhododendron maximum 

 and Rhododendron catawbiense, raised 

 in England and known as Rhododen- 

 dron delicatissimum, is in this climate 

 one of the most beautiful and desir- 

 able of garden rhododendrons. It has 

 white flowers tinged with pink, which 

 appear after those of most of the 

 other catawbiense hybrids have 

 passed. Another English hybrid of 

 the same parentage. Rhododendron 

 Wellesleyanum, is less hardy here 

 than either of its parents; and among 

 a large number of seedling plants of 

 Rhododendron maximum crossed the 

 some of the red-flowered catawbiense 

 hybrids, raised near Boston, only a 

 few have been able to bear the cold 

 of the New England winters. Other 

 species in the collection are the Eu- 

 ropean Rhododendron ferrugineum and 

 Rhododendron hirsutum, the Japanese 

 Rhododendron brachycarpum and Rho- 

 dodendron Metternichii, the first with 

 yellow and the other with rose-colored 

 flowers. Several plants of a hybrid of 

 this last crossed with garden hybrids 

 of Rhododendron catawbiense have 

 proved hardy in the Arboretum and 

 promise to be valuable additions in 

 the collection. Rhododendron ponti- 

 cum of southern Europe and Asia 

 Minor is hardy only in sheltered posi- 

 tions and is not a desirable plant for 

 this climate. In England it is the 

 common rhododendron of parks and 

 game preserves. Rhododendron cau- 

 casicum is an early-flowering species 

 from the Caucasus, with compact clus- 

 ters of yellowish white flowers. There 

 are several hybrids and varieties of 

 this handsome plant in cultivation 

 which have proved hardy in the Ar- 

 boretum and deserve to be better 

 known here than they are at present. 

 The flowers of many of these have 

 already faded, but a plant called cori- 

 aceum at the front of the group, just 

 beyond the turn from the Valley Road 

 into Hemlock Hill Road, gives a good 

 idea of the plants of this parentage. 



The large plants in the collection 

 are all hybrids of Rhododendron ca- 

 tawbiense and it is these hybrids 

 which are generally planted in Ameri- 

 can gardens. They are of different 

 parentage and have been obtained by 

 crossing Rhododendron catawbiense 

 with Rhododendron maximum. Rhodo- 

 dendron ponticum, and with Rhodo- 

 dendron arboreum, and other species 

 with highly colored flowers from the 

 Himalayas. A large number of these 

 hybrids are cultivated in Europe, but 

 only a few of them in which the blood 

 of Rhododendron catawbiense predom- 

 inates are really hardy in New Eng- 

 land. 



The Arboretum is often asked for a 

 list of the varieties which can be 

 grown here. The following which can 

 be seen in the collection either as 

 large cr small plants have been the 

 most successful in the neighborhood 

 of Boston: album elegans. album 

 grandiflorum, atrosanguineimi, bi-col- 

 or, Charles Bagley, Charles Dickens, 

 delicatissimum, Edward S. Rand, Ev- 

 erestianum, F. L. Ames, H. W. Sar- 

 gent, Hannibal, Kettledrum, King of 



the Purples, Henrietta Sargent, Lady 

 Armstrong, Mrs. Millner, Mrs. Charles 

 Sargent, Mrs. Harry Ingersoll, purpur- 

 eum elegans, purpureum grandiflorum, 

 roseum elegans, Sefton. 



Like most plants of the Heath Fam- 

 ily to which the rhododendrons be- 

 long, it is impossible to cultivate them 

 in soil impregnated with lime. The 

 area in the eastern states, therefore, 

 where they can be successfully grown 

 is comparatively small. 



The Laurels (Kalmia latifolia) will 

 be in bloom before the end of an- 

 other week. They are planted beyond 

 the rhododendrons at the northern 

 base of Hemlock Hill and furnish the 

 last and one of the most beautiful of 

 the yearly flower shows of the Arbor- 

 etum. 



Large plants of the Golden Chain, 

 Laburnum vulgare, are occasionally 

 seen in the neighborhood of Boston 

 where this handsome European tree 

 has long been planted. It is not very 

 hardy, however, and succeeds only in 

 sheltered positions. A better plant 

 for this region is the so-called Scotch 

 Laburnum, Laburnum alpinum of the 

 mountain region of central Europe. 

 This is a large shrub or small tree 

 blooming about two weeks later than 

 Laburnum vulgare, and the bright yel- 

 low flowers are produced in longer 

 clusters than those of the other spe- 

 cies. It grows rapidly and is perfectly 

 hardy. A large plant now in full 

 bloom can be seen close to the Shrub 

 Collection on the Forest Hills Road. 

 This is perhaps the most desirable 

 yellow-flowered shrub or small tree 

 which is hardy in this climate, and 

 it is unfortunate that a plant of this 

 character, which is so generally culti- 

 vated in Europe, should be so little 

 known in American collections. 



NEWS NOTES. 



Los Angeles, Cal. — Jack D'Ortenac 

 of the Redondo Floral Co. has sold his 

 share to Albert Knopf. 



Traverse City, Mich. — The Wolver- 

 ine Nursery Co. of Paw Paw, contem- 

 plate opening a branch office here. 



Paducah, Ky. — Fire damaged the 

 seed warehouse of Gardiner & Co. to 

 the extent of several thousand dollars, 

 on May 26. 



St. Ausgar, la. — The Gilbertson Nur- 

 sery Co. are building a 40x100 onion 

 storage house. A side track is being 

 laid to the building. 



Waterloo, Wis. — Thirty acres of 

 land in the southwest part of the 

 town have been purchased by the Mc- 

 Kay Bros. Nursery Co. 



Rockford, III. — A barn belonging to 

 R. H. Shumway. seedsman, was par- 

 tially destroyed by Are on May 25. 

 Damage about $500 with no insurance. 



Fulton, N. Y. — G. W. Perkins has 

 purchased the flower store of C. B. 

 Wetherby. Mr. Wetherby will here- 

 after devote himself to the growing 

 end of the business. 



Scranton, Pa. — A 30x100 brick build- 

 ing, four stories high, will be erected 

 by the Scranton Florist Supply Co., 

 beside their present building. It will 

 be used for making designs for flor- 

 ists use. 



