614 



GARDENERS' CHRONICLE 



Notes From Arnold Arboretum Bulletins 



Conius floridcf. which adds so much to the woodland beauty of 

 eastern North America from southern New England to Texas, 

 was covered here last Autumn with inflorescence-buds which ap- 

 pear during the Summer on short stems at the end of the branch- 

 lets between the upper pair of leaves, and consist of a cluster of 

 minute flower-buds enclosed in four scales which are brown and 

 more or less hairy during the Winter ; in Spring the stalk of in- 

 florescence lengthens from a quarter of an inch to an inch and a 

 half, and the scales which have protected the flower-buds open 

 and expand, turn pure white and form a flat corolla-like cup from 

 three to four inches in diameter. The enlarged pure white scales 

 which surround the flower-clusters are the conspicuous part of 

 the inflorescence, for the flower themselves are minute and 

 yellow-green. On many of the trees this Spring in the neighbor- 

 hood of Boston the white scales are discolored by dirty red-brown 

 streaks which make the trees seen from a short distance appear 

 pink. The cause of this discoloration is not evident, although it 

 may have been caused by the cold of Easter Monday following 

 several days of unseasonably hot weather. At that time, how- 

 ever, the inflorescence-buds of Conms Horida had scarcely begun 

 to swell. Whatever the -cause of the injury its occurence this 

 year, when there is an unusual bloom, is doubly unfortunate, for 

 the Flowering Dogwood often loses its flower-buds entirely in 

 New England as we are close to the northern limit of the range 

 of distribution of this tree, which further south flowers more 

 profusely and develops larger bud-scales. Forms of this tree 

 with the scales which surround the flower-clusters varying in 

 color from light to dark red (var. rubra) occasionally occur in 

 southern woods, and some of these forms have been propagated 

 by nurserymen and are popular garden plants, especially in the 

 neighborhood of Philadelphia, where there are many specimens 

 of the "Red-flowered Dogwood." Several plants of this variety 

 are now blooming by the shores of Jamaica Pond in Boston where 

 they are flowering more abundantly than usual, for the flower- 

 buds of this variety appear to be less hardy than those of the 

 typical form. This is unfortunate, for when the red and white- 

 flowered trees are planted together in masses thev produce when 

 in flower a brilliant effect. There is a form of Cornus florida 

 with pendulous branches, and another on which the flowers are 

 called double from the presence of an inner row of white inflor- 

 escence-scales. These abnormal forms, ho.wever, have little to 

 recommend them to the lovers of handsome trees. Cornus ftorida 

 is as handsome in the Autumn as it is in the Spring, for the upper 

 surface of the leaves turns bright red, the lower surface retaining 

 its pale Summer tint, and the abundant clusters of scarlet lustrous 

 fruits are -conspicuous and beautiful. Not less beautiful in .\ntuiTin 

 are two trees with bright yellow fruit which have recently been 

 found, one near Oyster Bay, Long Island, and the other in North 

 Carolina. 



AsaJcas. — The large orange red flowers of Rhododendron 

 (.hnlca) ia[>oniiuni are fast opening, and althou,£;h the plants 

 on the lower side of Azalea Path are not as full of flowers this 

 Spring as usual there are flowers enough to show their beauty. 

 Rhododendron japonicum is a common shrub on grass-covered 

 foothills of the mountains of central Japan where it is a vigorous 

 shrub froin three to six feet high with stout erect stems and clus- 

 tered flowers froiTi an inch and a half to two inches in diameter 

 which open as tlie leaves unfold. More beautiful is the hybrid 

 .•\zalea Louisa Hunnewell {Rhododendron koslerinnunt var. 

 Louisa Hunne-a'el!) which was raised at Wellesley by crossing 

 A', japonieuni with 7?. molle (the R. sinense of many authors), 

 and is the handsomest of the hylirid .\zak'as. A number of plants 

 of this hylirid arc now in flower on ihe lower side of Oak Path 

 near its junction with .\zalea Path, and opposite a group of plants 

 of Rhododendron japouieum. On the lower side of Oak Path, 

 near the junction with Azalea Path, plants of a hybrid between 

 Rhododendron ohiusum amoenum (the well known Acalea amoena 

 of gardens) and R. obtusum kcrmpferi (Azalea keempferi) are 

 now in bloom. This hybrid was raised at the Arboretum several 

 years ago by Jackson E)awson and has been naiued Rhododendron 

 arnoldiannm. The plants are dwarf in habit and the flowers on 

 the different plants vary in color between that of the flowers of 

 the two parents. A few of the plants in this group are worth 

 propagating for the edges of beds and for the rock garden. 



T-c^'o Anieriean Acaleas. — Plants of Rhododendron niididonim 

 and A', roseuni are in bloom on the lower side of Azalea Path, 

 and the grouns of these plants which are now side by side afford 

 opportuin'ty for the studv of these two New Ensland Azaleas. 

 Tlic flowers of R. nudiftorum, which are pale pink and open a 

 few days earlier than those of R. roseuni. have not the fragrance 



wliicli adds so much to the value of the rose-colored flowers of 

 R. ruscnni. The fact that this plant can grow in soil strongly 

 impregnated with lime will make its cultivation possible, it is 

 hoped, in parts of the country where, on account of lime in the 

 soil, no other Rhododendron can be kept alive. 



Rhododendrons with evergreen leaves are widely scattered over 

 temperate regions of the northern hemisphere and extend into the 

 tropics in southern and southeastern Asia. Several hundred 

 species are now recognized, the largest nuinber on the eastern 

 Himalayas and on the moun.tains of southwestern and western 

 China where botanical explorers have recently found innumerable 

 new and often handsome species. One or two species grow in 

 northern China, two in central Japan, one in the Pacific states, 

 and five in the Atlantic states of North America; two species 

 grow on the mountains of central Europe and four in the Cau- 

 casus. The number of species which can be successfully grown 

 in the Arboretum is only nine ; four from eastern North America, 

 one from Japan, one from China, one from the Caucasus and two 

 from Europe. Of these several are rare in American gardens, in 

 which hybrids are generally cultivated. Eastern North America 

 is not a Rliododendron country. A few of them grow better on 

 Long Island than they do in New England; they might grow 

 more successfully in Pennsylvania and Delaware where they 

 have not been very largely planted, or in some favored valley of 

 the Piedmont region of Virginia or North Carolina ; further south 

 the Summer sun is too hot for many of the species. On the north- 

 west coast of this continent in western Oregon, Washington and 

 southern British Coluiribia the soil, moisture and temperate cli- 

 mate are favorable to broad-leaved evergreens, and it is in that 

 region that it seems possible to establish a collection of Rhodo- 

 dendrons which might equal and perhaps surpass the great collec- 

 tions of southwestern England, in the best of which several hun- 

 dred species now flower every year. In the United States 

 Rhododendrons have been more largely planted and better cared 

 for in the neighborhood of Boston than in other parts of the 

 country; and judging by the best collection in America, at least, 

 of the so-called Catawbiense hybrids on which incessant care, in- 

 telligence and money have been expended continuously for sev- 

 enty years the results which can be obtained from the cultivation 

 of these plants in New England are not great in comparison with 

 the residts olitained in regions better suited to their requireinents. 



Rhododendrons usually grow on mountain slopes where, 

 although the atmosphere is saturated with moisture, their roots 

 are in well drained soil, and where they are often protected in 

 Winter by snow. Here in New England they grow best when 

 planted on the north side of evergreen trees, protected from the 

 stimulating effect of the hot sun of March which excites growth 

 and increases the danger from late frosts. Planted in such a 

 position at the base of Hemlock Hill in the .Arboretum there are 

 good plants of Catawbiense hybrids. F;hododendrons are not 

 particular about soil provided it is well drained and is free of 

 lime. A few of the new Chinese species grow naturally in lime- 

 stone soil, but none of them are hardy in the eastern states. For 

 the Rhododendrons which can be grown here lime is fatal, and 

 persons wlio go on year after year trying to overcome this pe- 

 culiarity of nearly all plants of the Heath Faiuily are throwing 

 away their labor and money. Rhododendrons suffer from in- 

 suflicient moisture at the roots and cannot be safely planted with- 

 in reacli of the roots of vigorous trees which deprive them of it. 



The species of Rhododendrons whicli liave proved hardy here 

 are the eastern American R. maximum. R. eatatcbiense. R. minus 

 and R. earolinianum, the European 7?. ferrugineum and R. hirsu- 

 tnm. the Caucasian R. smirnoii'ii. the Chinese R. mieranthum and 

 the Japanese R. braehyearpum. The four .American species are 

 perfectly hardy and can be grown without difficulty. R. maximum 

 is tlie largest of these, becoiuing sometimes a small tree in the 

 sheltered valleys of the southern Appalachian mountains. It has 

 beautiful, dark green, lustrous leaves pale on the lower surface, 

 and clusters of pink and white flowers whicli do not open here 

 until July and are a good deal hidden liy the branches of the vear 

 which have nearly finished their .growth before the flowers appear. 

 R. ealaivbiense is a round-topped shrub with beautiful folia.ge and 

 lilac purple flowers of a distinctly disagreeable color. It grows 

 on the southern Appalachian Mountains, sometimes covering neai 

 the summits of the hiuhest peaks, at altitudes of between five 

 or si.x thousand feet, thousands of acres with impenetrable thick- 

 ets ; It occurs, too, sparingly in the Piedmont region of North 

 Carohna and on the mountanis of northern .\labama. R. earolin- 

 ninum and R. minus are southern Appalachian species; the former 

 IS a dwarf compact shrub with leaves covered below more or less 

 thickly with rusty brown scales, and coinpact clusters of small 

 (Continued on page 616) 



