June 27, 1908 



HORTICULTURE 



845 



Notes from the Arnold Arboretum 



Uiie ol' the liiiest ul lliu uauve Aii'uu-ruot^ is Vibur- 

 num venosum which forms a broad round shrub from 

 six to twelve feet in height now covered with numerous 

 showy white flower clusters. Still handsomer is its 

 variety V. venosum var. Canbyi which has darker green 

 and larger leaves and somewhat larger flower clusters; 

 it flowers somewhat later and is a native of Pennsyl- 

 vania, while the true V. venosum grows along the coast 

 from Massachusetts to New Jersey. Both these Arrow- 

 roots were passing formerly together with a southern 

 species, V. scahrellum, under the name V. molle men- 

 tioned in the last issue as. a shrub but recently intro- 

 duced into cultivation and still little known. In habit 

 and general appearance V. venosum and its variety are 

 much like V. pubescens and V. dentatum and like those 

 very desirable shrubs particularly for borders of shrub- 

 beries with their compact habit, clean foliage not liable 

 to injury by insects and fungi and assuming a hand- 

 some fall coloring and with their showy flowers followed 

 in autumn by attractive bluish black fruits. Though 

 almost alike in their ornamental qualities these Arrow- 

 roots differ in the time of flowering and therefore are 

 all equally desirable; the first is V. pubescens, about 

 two weeks after it V. dentatum begins to bloom and a 

 week later V. venosum. closely followed by its variety 

 Canbyi. 



Another shrub now made attractive by its white 

 flower cluster similar to those of the Arrow-roots is 

 Co7-nus obliqua (C. Purpusi) formerly confounded with 

 F. Amomum from which it differs in its looser habit 

 and narrower and smaller leaves wMtish beneath ; it 

 flowers a little in advance and more profusely. An 

 interesting and handsome hybrid of C. obliqua and the 

 graceful C. paniculnta is C. Arnoldiana in habit much 

 like C. paniculata , but forming a larger and more com- 

 pact shrub and therefore of more tlian botanical inter- 

 est; it originated at the Arboretum. 



A common native shrub but nevertheless of much 

 ornamental value in suitable places partictilarly on the 

 Irorders of ponds and water courses is the Sweet Elder, 

 Snmbucus canadensis, which is a very effective shrub 

 when covered with its large clusters of white flowers 

 followed later bj' purplish black berries. A variety of 

 this species with finely dissected leaves, S. canadensis 

 var. acutiloba, is highly ornamental on account of its 

 light and airy appearance and is to be counted as one 

 •of the best cut-leaved shrubs; it is certainly handsomer 

 than 8. nigi-a var. laciniata. It has been but recently 

 introduced into cultivation and is still little known. 



The latest of the Hawthorns to bloom is the Wash- 

 ington Thorn, Crataegus cordata or C. Phacnopyrum, 

 which must be classed as one of the most ornamental of 

 the whole genus. It is a small tree with handsome lus- 

 trous foliage changing in autumn to brilliant colors and 

 with abundant white flowers followed in autumn by 

 g-lossv bright red fruits remaining on the tree late into 

 the winter. Xot tlio least of its good points is its ap- 

 parent immunity from the leaf-miner disfiguring our 

 Hawthorne so mitch in si)ring wlien they would be such 

 beautiful objects with their wealth of white flowers and 

 delicate young foliage. 



Magnolia marroplnjThi is now ailorned witli its big 

 -white flower by far tlie largest of any North American 

 tree. It is certainly a h.ighly ornamental tree even when 

 not in bloom on account of its large leaves which give 

 to it an almost tropical appearance : unfortunately it is 

 not perfectly hardy in this section of the country at 

 least while voung, when it needs some slight protection. 



Older trees, however, stand even severe winters quite 



well ill eastern Massachusetts. Also the shrubby M. 

 g la II (11 shows now its handsome white cup-shaped 

 flowers. 



A ])retty little low shrul) particularly adapted for 

 rockeries and gravelly slopes is Cytisus albus var. schip- 

 kaensis forming a dense prostrate shrub covered with 

 numerous heads of white flowers, a color rare in the 

 genus Cytisus. An ally of it Genista tinctoria is now 

 beginning to show its spikes of bright yellow flowers; 

 it is a low ujjright shntb well adapted for covering dry 

 slopes and perfectly hard}', in fact it has become natur- 

 alized in many places of similar description in the 

 northeastern states. Another handsome low Legumi- 

 nous shrub for rockeries is Calophaca wolgarica with 

 deep yellow flowers in short racemes; it is sometimes 

 grafted high on Caragana and forming then very attrac- 

 tive small standard trees. 



As one of the few Maples with ornamental fruits 

 Acer tataricum merits to be noted; it is a handsome 

 small shrubby tree now very attractive with its light 

 red fruits. 



Arnold Arboretum., Jamaica Plain, Mass. 



British Horticulture 



A RHODODENDRON SHOW 



According to their usual custom, Messrs. John 

 AVaterer & Sons are this month making a brilliant dis- 

 play of rhododendrons in an immense marquee erected 

 in the Eoyal Botanic Gardens. The collection inchades 

 the leading varieties which Messrs. Waterer have 

 brought to the front, and these are of meritorious stan- 

 dard of culture. A grand effort is produced with the 

 grouping of the variotts gay tints on the undulating 

 ground beneath the canvas, and one is impressed with 

 the great value of the rhododendron for producing a 

 tiold display when judiciously arranged. This notable 

 event in the London season has done a great deal in 

 popularizing the rhododendron. Messrs. Waterer for 

 some years have made a specialty of rhod,odendrons, a 

 large acreage being devoted to their cultivation at their 

 American Nurseries at Bagshot. A large number of 

 the leading named sorts have been raised by the firm, 

 for which the demand is well maintained, orders being 

 received from all parts of the world. In the course of 

 an interview sometime ago, one of the members of the 

 firm said, "Exclusive of the little seedlings, we send out 

 from 70,000 to 100,000 rhododendrons each year. 

 Sometimes, as only the other day, we have a retail 

 order for '2.000 of one variety. These are all named 

 varieties, pjopagated by grafting and layering — by 

 layering as much as possible."' The nursery is also 

 noted for its hollies and yews and shrubs which are 

 also supplied in large quantities. 



A NEW TOMATO DISEASE 



The tomato crop in some parts has recently Ijeen 

 found to be attacked by a disease which has not pre- 

 viously Iieen known to exist in this country, according 

 to Mr. H. T. Gussow, who contributes an article to the 

 Board of Agriculture Journal. The disease, it is 

 stated, was first reported from South America, the 

 native country of tlie tomato. From its sudden appear- 

 ance in Britain it is assumed that the fungus has been 

 introduced from abroad with impo:-ted tomatoes. A 

 cron of outdoor tomatoes in Gloucestershire was entirelv 



