848 



HORTICULTURE 



June 26, 1916 



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A FEW SHOP-WORN 

 LAMPS AT A BARGAIN 



RHODODENDRONS IN THE AR- 

 NOLD ARBORETUM. 

 In the lliilletin issued .\pril 28th 

 attention was called to the damage 

 which the rhododendrons in the Ar- 

 boretum had suffered during the win- 

 ter, and It was suggested that It was 

 caused by the severe drought of the 

 autumn, followed by the unprecedent- 

 ed drought of March and early April, 

 and not by cold which had not been 

 exceptional. The Arboretum rhodo- 

 dendrons certainly suffered from 

 drought, but dryness alone will hardly 

 account for such a destruction, for in 

 other places near Boston plants, in 

 much drier and more exposed posi- 

 tions than those in the Arboretum are 

 reported to have come through the 

 winter uninjured. Some of the plants 

 which were killed here have been 

 twenty-five or thirty years in the coun- 

 try. These plants were grafted on 

 lihoilodendron pontivum. a plant 

 which is not hardy here and is there- 

 fore not suitable slock for Catawbiense 

 hybrid rhododendrons to be grown in 

 this climate. It is well known that 

 these old grafted plants often lose 

 large branches from what gardeners 

 call "canker," and it is not impossible 

 that the old plants killed in tlic Ar- 

 boretum have been gradually failing 

 for several years from the influence 

 of the stock on which they had been 

 grafted, and were therefore susceptible 

 to extreme climate conditions. This 

 view is borne out by the fact that 

 when plants of a particular kind were 

 killed and others of the same kind 

 were not killed it was always the old- 

 est and largest plants of the variety 

 that suffered. It has generally been 

 siipposed that it was the cross with 

 I{. inbonum and other Indian species 

 which has made so many of the vari- 

 eties of li. ratnubiense tender in this 

 climate, but some of the varieties 

 which show in their bright red flowers 

 this influence, like Atrosanguineum. 

 Charles Dickens, and H. \V. Sargent 

 are uninjured, while many of the pale- 

 flowered kinds like Lady Grey Eger- 

 ton, Mrs. H. S. Hunnewell and Deli- 

 catissimum have been killed. The last 

 is a hybrid between li. latawbiense 

 and R. maj:imum. and for the last 

 thirty years has been considered one 

 of the hardiest and most desirable of 

 the rhododendrons which have been 



planted in New Kngland. Plants of 

 the following catawbiense varieties 

 have been killed in the Arboretum, 

 but of the varieties marked with a 

 star one or more, but not all the in- 

 dividuals in the collection, have been 

 killed. On many plants which have 

 not otherwise suffered the buds have 

 been killed or injured. 'Adolf, Alaricli, 

 Albin, .-Mfred, •Atrorubnim, 'Bis- 

 marck, Bluebell, 'Butlerianum. Cine, 

 Daniel, •Delicatissimum, *Uiana, 

 Duchess of Connaught, Earl of Shan- 

 non, Egge, FJlysium, Fee, *F. L. Ames. 

 •F. B. Hayes, *Hanna Felix, Herkules, 

 Jay Gould, *King of the Purples, 

 •Lady Grey Egerton. Madame Wagner, 

 •Marquis of Waterl'ord, Mum, 'Mrs. 

 Harry Ingersoll, .Mrs. H. S. Hunnewell. 

 Mnemoisyne, *Prometheus, *R. S. 

 Field, Saimoneum roseum, Sir H. Hav- 

 erlock. 



On the whole the different forms of 

 li. caucasUum have come through the 

 winter in comparatively good condi- 

 tion. The plants of the varieties Cleo 

 and Ochroleucrum have been killed, 

 and the flower-buds of a few others 

 have suffered. The following varieties 

 however, are uninjured, or have suf- 

 fered only slightly: Boule de N'eige, 

 Coriaceum, Jacksonii and .Mont Blanc. 

 In some years, when conditions are 

 comparatively favorable, rhododen- 

 drons flourish in this climate; in other 

 years when conditions are less favor- 

 able they suffer. Compared with these 

 plants as they grow in England and 

 Scotland, rhododendrons are never 

 really successful here. This is not a 

 climate for rhododendrons, that is for 

 the sort of rhododendrons European 

 nurserymen usually propagate and 

 send to this country. It is true some 

 of them can be kept alive here for a 

 great many years but they require 

 special care. The soil in which they 

 grow best has to be specially pre- 

 pared for them; they require shelter 

 from the sun of early spring, and a 

 great deal of moisture. Of late years 

 they have suffered terribly from the 

 attacks of the lace-wing fly which 

 turns the leaves brown and makes 

 them fall prematurely, thus weaken- 

 ing the plant. Rhododendrons. like 

 many other plants of the Heath fam- 

 ily, cannot grow in soil impregnated 

 with lime; they are not hardy very 

 far north of Boston, and south of Phil- 

 adelphia, except in the elevated re- 

 gions of the interior, it is too hot for 

 them in summer, so that the region in 

 the eastern states where these plants 



can be grown at all is not a large one. 

 Here in eastern Massachusetts there 

 are only four species of broad-leaved 

 evergreen rhododendrons which are 

 perfectly hardy; these are the native 

 R. maximum, R. catawbiense from the 

 high slopes of the southern Appala- 

 chian Mountains, R. carolinianum from 

 the same region, and R. Sniirnowll 

 from the Caucasus, and If we can hope 

 for a race of hybrid rhododendrons 

 better suited to the conditions of the 

 New England climate than any we 

 now possess, it will be obtained by 

 mingling the blood of these four 

 si)ecies and by excluding entirely the 

 blood of the Himalayan species to 

 which the garden rhododendrons of 

 Europe owe a large part of the bril- 

 liancy of their flowers. 



Rhododendron Smirnowli. 



This is a plant from which a good 

 deal may be expected. It has been 

 growing in the Arboretum for several 

 years and has not suffered from cold 

 or drought. When, however, the plant 

 is fully exposed to the sun the leaves 

 often droop and their edges infold, 

 and it does better in partial shade. 

 The leaves are pale grayish green 

 above and below are thickly covered 

 with i)ale felt which successfully pro- 

 tects them from the attacks of the 

 lace-wing fly. The flowers are of good 

 size and of pleasant shades of pink or 

 rosy pink, and are borne in large 

 clusters. As compared with the dark 

 green leaves of R. catawbiense those 

 of this plant are less attractive, but 

 the flowers are much more beautiful 

 in color and are equally large. Several 

 hybrids of R. Smirnowli with varieties 

 of R. catawbiense have been raised 

 in Europe, and there are a few of 

 these in the Arboretum collection. 

 They have proved to be good garden 

 plants here, flowering earlier than R. 

 Smirnowli and producing larger pink 

 flowers; they have never been injured 

 in the Arboretum, but as there is only 

 a trace of the felt left on their leaves 

 they will probabl.v suffer from the 

 lace-wing fly. Rhododendron carolin- 

 ianum is said to have suffered last 

 winter in a few places near Boston, 

 but it was uninjured in the Arboretum 

 and in several other Massachusetts 

 gardens. It is the most beautiful of 

 the dwarf small-flowered rhododen- 

 drons which can be grown in this 

 climate and may prove valuable to 

 cross with other species. 

 Arnold Arbonttim BuUelin .June X. 



