414 



HORTICULTURE 



October 26, 1918 



ARNOLD ARBORETUM NEWS. 



The Red or Scarlet Maple (Acer 

 rubrum). 



The flowers of the Red Maple are 

 red on some Individuals and on others 

 pale yellow, trees with flowers of these 

 two colors growing together over a 

 large part of the region inhabited by 

 this tree. On some trees the autumn 

 leaves are of different shades of red or 

 scarlet and others clear yellow. If any 

 reader of these Bulletins has noticed 

 if the autumn color of the leaves of 

 trees with red flowers is red and that 

 of trees with yellow flowers is yellow 

 the Arboretum will be glad to hear 

 from him on the subject. One tree in 

 the Arboretum in interesting from the 

 exceptionally beautiful color of the 

 leaves at this season and from the fact 

 that it is a grafted tree raised to show 

 the possibility of propagating trees 

 exceptional in the color of their au- 

 tumn foliage. This branch of arbori- 

 culture has not been much practised, 

 but when it is realized that the leaves 

 on some Individual trees or shrubs of 

 a species assume more brilliant colors 

 than those of other individuals of the 

 same species, that this peculiarity is 

 constant from year to year and that it 

 can be preserved and multiplied by 

 grafting, there is no reason why a de- 

 mand for trees with exceptionally 

 beautiful autumn leaves should not 

 make possible the supply, just as the 

 demand for trees of abnormal habit or 

 with abnormal foliage, like a Mulberry 

 with pendulous branches or a Beech 

 with purple leaves, has created the 

 supply 



Mountain Ashes. 

 Many of these trees are now growing 

 well in the Arboretum, and some of 

 them are unusually full of fruit this 

 year and handsome and interesting 

 objects. Mountain Ashes have leaves 

 divided into numerous narrow leaflets, 

 compact clusters of white flowers 

 which are followed by scarlet, yellow, 

 orange-colored, pink or white, usually 

 globose fruit which varies from a 

 quarter to three-quarters of an inch 

 in diameter. The best known and 

 most commonly planted of these trees 

 in the United States is the European 

 Sorbus Auctipaiia, the Rowan tree of 

 Scotland. It is a tree from forty to 

 sixty feet tall, of pyramidal habit 

 while young, with erect branches 

 which as the tree grows older spread 

 out into a broad and graceful head. 

 Here the leaves retain their color until 

 the autumn is far advanced, and dur- 

 ing September and October the con- 

 trast between the bright green leaves 

 and the drooping clusters of brilliant 

 red fruit makes this tree an attractive 

 object until the birds strip it of its 



fruit. This Mountain Ash is common 

 and widely distributed over the cooler 

 parts of Europe and was probably 

 early introduced into North America 

 where it has been much planted in the 

 extreme northern states and in Can- 

 ada. Several varieties are recognized. 

 The handsomest of these is the Mora- 

 vian Mountain Ash (var. moravica or 

 iJulcis) of northern Austria. This is 

 a tall tree with a smooth stem, leaves 

 with narrower leaflets than those of 

 the type and larger Snd sweeter fruit. 

 It is used as food in central Europe. 

 This Mountain Ash has grown in the 

 Arboretum very rapidly and promises 

 to become a large tree. There are 

 forms of the Rowan tree with pendu- 

 lous branches (var. pendula) and 

 with fastigiate branches (var. fasti- 

 giata). There is a form with yellow 

 fruit and a variety from eastern 

 Europe (var. Uinuginosa) the leaves 

 of which are covered on the upper sur- 

 face with stiff hairs and are downy 

 on the lower surface. 



Asiatic Mountain Ashes 

 In recent years a number of thtse 

 trees have been brought from eastern 

 Asia to the Arboretum and some of 

 them promise to be valuable trees here. 

 The Japanese Sorhus commixta was 

 the first of them which was planted 

 here and it has now been growing in 

 the Arboretum since 1888. It has 

 smaller flower-clusters than the Euro- 

 pean species, the bright red fruit is 

 smaller and its chief value is in the 

 bright orange and red color of the 

 leaves in autumn. A much handsomer 

 plant is iS'orbw.s peki7icnsis, a native of 

 northern China, which is now well es- 

 tablished in the Arboretum. It is a 

 slender tree with narrow leaflets, com- 

 pact clusters of flowers and lustrous 

 pink or yellowish fruit in drooping 

 clusters. The color of the fruit is un- 

 usual among Mountain Ashes. The 

 narrow leaflets give this tree a particu- 

 larly open and attractive appearance. 

 The largest and handsomest specimen 

 in the Arboretum is in the nursery 

 plantation near the top of Peter's Hill. 

 Sorbus Koehneana has flowered and 

 fruited in the Arboretum this year for 

 the first time. It is a shrub now about 

 three feet high with slender erect 

 stems, small leaves with numerous 

 narrow leaflets, small compact clusters 

 of flowers, and snow-white fruit. It is 

 a beautiful shrub which when better 

 known will become common in gar- 

 dens. The plants in the Arboretum 

 were raised from seeds collected by 

 William Purdom in northern Shensi. 

 Sorbus pohuashanensis, so named be- 

 cause it was discovered on the Pohua 

 ,^lountains in northern China, is also 

 well established in the Arboretum. 

 The leaflets are rather broader than 



those of the Rowan tree, but it has the 

 red fruit and woolly buds of that 

 species and is not superior to it for 

 general cultivation. Although they 

 are not as large and shapely trees as 

 some of the Old World species, the 

 two Mountain Ashes of eastern North 

 America, Sorbus americana and its 

 variety decora, have no rivals in this 

 group in the beauty of the great droop- 

 ing clusters of orange fruit and in the 

 orange and red tints of their autumn 

 foliage. They are small trees or larse 

 shrubs and are often planted in gar- 

 dens in Canada, northern Michigan 

 and Minnesota, but unfortunately are 

 still little known in those of eastern 

 Massachusetts. 

 The Spindle-Tree or Burning Bush. 

 By these names some of the species 

 of Evonymus are popularly known. 

 Evonymus is a genus of shrubs or 

 small trees widely distributed over 

 the temperate regions of the northern 

 hemisphere and more abundant in 

 species in eastern Asia than in North 

 America or Europe. As a garden plant 

 the species with deciduous leaves are 

 chiefly valuable for their showy fruits, 

 although the leaves of some of the 

 Asiatic species become bright colored 

 in the autumn. The flowers of all the 

 species are inconspicuous. The fruit 

 is a scarlet, red or whitish capsule, 

 which when it opens displays the 

 seeds enclosed in a bright orange, scar- 

 let or pink fleshy covering or aril. In 

 the last issue of these Bulletins the 

 autumn beauty of the Japanese A,'. 

 (ilatus was referred to. Another 

 species with leaves conspicuous at 

 this season is E. Maackii from the 

 Amoor region of eastern Siberia. This 

 is a large, round-topped shrub, the old- 

 est specimen in the collection being 

 now eight or ten feet tall and twelve 

 or fifteen feet across the head. The 

 leaves are narrow, pointed at the ends, 

 drooping, and early in October are dull 

 red on the upper surface and pale 

 green on the lower surface. The fruit 

 is produced in great quantities and is 

 rose color and half an inch in diam- 

 eter, and the seeds are bright orange- 

 scarlet and very lustrous. Although 

 the leaves of the Japanese E. yeddoen- 

 sis do not turn as brilliantly as those 

 of some of the other Asiatic species 

 and fall early, this round-topped shrub 

 is one of the handsomest of the group 

 when it is covered with its large, rose- 

 colored capsules which remain on the 

 branches long after the leaves fall. 

 E. Bungeanus. a small tree from north- 

 ern China, is an old inhabitant of the 

 Arboretum, and every year it is con- 

 spicuous when its pale yellow fruit 

 opens and the rose-colored seeds ap- 

 pear and the narrow drooping leaves 

 turn pale yellow. 



